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Reference of Measurements in Halacha

2024-07-23T20:43:56Z

Schwartz: /* Bein HaShemashot and Tzet Hakochavim */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Distance of Mil===

#
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Time period of Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Some consider a ''mil'' to be 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
### Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
### Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
### There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref name=":0">Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref name=":1">Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''
*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear.</ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref name=":2">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref name=":3">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref name=":4">Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref name=":5">Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref name=":6">Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref name=":7">Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref name=":8">Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref name=":9">Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot and Tzet Hakochavim===

#The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day and after which it is night.<ref>Gemara Shabbat 34b. There is a dispute there between Rabbi Yehuda Rabbi Nechemia and Rabbi Yosi. Rabbi Yehuda says that ''bein hasmashot'' begins when the sun (''lit.)'' sinks and lasts until the upper part of the eastern sky is dark. Rabbi Nechemia says that ''bein hashmashot'' starts when the sun sinks and lasts for the duration of 0.5 ''mil.'' Rabbi Yosi says that ''bein hasmashot'' lasts for "a blink of an eye". Gemara Shabbat 35b quotes Rav Yehuda in the name of Shmuel that when there is one star it is still day, two stars is ''bein hashmashot'', three stars is night. Gemara Shabbat 35a writes that the halacha is in accordance with both Rabbi Yehuda and Rabbi Yosi. Rif Shabbat Chap.2, Rosh Shabbat Chap 2:23, and others maintain that the halacha follows Shmuel as well.
*These are the bases for the discussion amongst the ''poskim'' as to the time of ''bein hashmashot''. To see how this translates into the common halacha and for a full discussion see Hazmanim B'halacha Chap. 40</ref><ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot|bein hashemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot|bein hashemashot]]? Rabbi Yehuda says that [[Bein HaShemashot|bein hashemashot]] starts from [[Shekiyah]] when the eastern horizon darkens, and concludes 3/4 of a ''mil'' later when the upper part of the sky becomes dark as well. Rabbi Yosi says that [[Bein HaShemashot|bein hashemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.''<ref>Ginzei Kedem V pg.37, See Teshuvat Maharam Alshakar 96 quoting Teshuvat Rav Sherira Goan and Rav Hai Goan. For a more complete list see Hazmanim B'halacha - Rav Benish Chap. 41 3-5.
*Notably, Gra O.C. 261:11, Y.D. 262:9, and Rav Shneur Zalman of Liadi (Baal HaTanya) Siddur - Seder HaChnosat Shabbat, ''pasken'' in accordance with this view and it has thus become accepted halacha in most circles.

*Notable exceptions to this were Rav Yoel Teitelbaum of Satmar and Rav Yekusiel Yehuda Halberstam of Tzanz-Klausenburg who wrote that the halacha is in accordance with Rabbenu Tam. See Divrei Yoel 18, Shefa Chaim - Kovetz Igros Kodesh I:11-20

*Hazmanim B'halacha Chap.44:5 writes that regarding the start of Shabbat even the Satmar Rav and the Tzanz-Klausenburger Rav went in accordance with the ''geonim.''
*Igrot Moshe IV:62 writes that we are not able to resolve a dispute between ''rishonim'' and we must be stringent according to both views.</ref> Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.<ref>Sefer HaYashar New Edition 221, Tosfot Shabbat 35a ''s.v''. trei, Tosfot Pesachim 94a ''s.v.'' Rabbi Yehudah. Many other ''rishonim'' agreed with Rabbenu Tam, see Hazmanim B'halacha Chap 42:6-10 for a complete list.</ref><ref>There are additional opinions as well; yet they are not the accepted halacha.
*Sefer Yeraim 274 writes that ''bein hashmashos'' begins 0.75 ''mil'' before sunset and lasts until sunset at which time it is night. Biur Halacha 261:2 ''s.v. mitchilas'' writes that it is worthwhile to start ''Shabbat'' before that time.

*Sefer Raavan 2 writes that ''bein hashmashot'' begins at sunset and lasts 5 ''mil'' until ''tzet hakochavim.''

*See Hazmanim B'halacha Chap 41 for a complete discussion.</ref><ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Biur Halacha 261:2 ''s.v. kodem'' writes that it varies according to one's location.</ref>
#Just as by ''alot hashachar'', there is a dispute among the ''poskim'' as to the value of a ''mil'' and the amount of ''mil'' between ''alot'' and ''hanetz'', so too, this dispute applies regarding ''tzet hakochavim.''<ref>Dvar Yom Chap. 6</ref>
#Similarly, just as by ''alot'' there is a dispute as to whether the time is measured in degrees, ''shaot shavot,'' or ''shaot zmaniot''; that dispute applies regarding ''tzet hakochavim'' as well.<ref>There are three methods in the ''poskim'' for applying the ''zman'' of the Gra and of Rabbenu Tam: degrees, ''shaot zmaniot, shaot shavot.''
*Degrees - The time of ''tzet hakochavim'' is an astronomical event; the timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''tzet'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. ''Tzet'' is always when the sun is at a certain point below the horizon. According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''tzet'' occurs 72 minutes after sunset, they do not mean to say that ''tzet'' occurs 72 minutes after ''shkiya'' in every locale, on every day of the year. Rather, they are discussing the time of ''tzet'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.

*The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
*The following applies assuming that a ''mil'' is either 18, 22.5, or 24 minutes.

*According to the Gra the following times apply

*At 13 1/2 minutes the sun is 3.7º below the horizon.

*At 16 7/8 minutes the sun is 4.4º below the horizon.

*At 18 minutes the sun is 4.7º below the horizon.

*According to Rabbenu Tam the degrees would be the following.

*At 72 minutes the sun is 16.1º below the horizon.

*At 90 minutes the sun is 19.75º below the horizon.

*At 120 minutes the sun is 25.9º below the horizon.

*Shaot Zmaniot

*Some hold that the times given are the actual times for ''tzet''; yet they are not measured in terms of a 60-minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes. Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' the following way: 72 minutes = 96 minutes and 13.5 minutes = 18 minutes.

*Fixed Minutes

*Some hold that ''tzet'' is determined by fixed minutes.</ref>
#Because of all these factors, there are different customs as to the time of ''bein hashmashot'' and ''tzet hakochvim.''
#Nowadays there is a widespread ''minhag'' to start ''bein hashmashot'' at ''shkiya'' in accordance with the ''zman'' of the ''geonim.''<ref>Hazmanim B'halacha Chap 44:5. He mentions that even those who were vehement in upholding the ''minhag'' to go in accordance with Rabbenu Tam agreed to be stringent to stop all ''melacha'' on ''Erev Shabbat'' at ''shkiya.'' </ref>
#The time for ''tzet hakochavim'' is a bit more complicated because neither the time of Rabbenu Tam or the time of ''geonim'' coincide with the time that the stars actually become visible. There are explanations given both according to Rabbenu Tam and the ''geonim'' that the time for ''tzet hakochavim'' is ultimately dependent on the appearance of three stars.<ref>*Dvar Yom appendix 1 lists over 75 sources that the custom was to set ''tzet'' based on the appearance of stars and not based on ''mil.''

*Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.

*Minchas Kohen 2:5 ''s.v.'' ''she'im'', Biur Halacha 261:2 ''s.v. kodem'' and Igros Moshe O.C. IV:62 agree. Rav Moshe writes that in New York the time for ''tzet'' according to Rabbenu Tam is 50 minutes after ''shkiya''; however, he writes that it is proper for G-d fearing Jews to wait 72 minutes to end Shabbat, as was the custom in Europe. See Hazmanim B'halacha Chap. 42 for a complete discussion.</ref> Thus, there are generally two ''minhagim'' as to when ''tzet hakochavim'' is.<ref>Dvar Yom Chap. 6:10-31</ref>
##With the appearance of 3 stars.<ref>Dvar Yom Chap. 6:18-24</ref>
###There are many opinions as to the number of degrees that the sun must be below the horizon for 3 medium stars to appear. They range between 5.7º and 8.1º.<ref>Dvar Yom Chap. 6:17</ref>
###For ending ''Shabbat'', the Shulchan Aruch rules that, to avoid mistakes, one must be stringent and wait until 3 small stars are visible. The ''shiur'' for this time was set by Rav Tukatzinski at 8.5º.<ref>Dvar Yom Chap. 6:18-19</ref> Most calendars both in Israel and abroad (who are not using 72 minutes fixed) use this measurement.<ref>Dvar Yom Chap. 6:20</ref>
####In Israel this ''shiur'' results in ''Shabbat'' ending between 36 - 42 minutes after ''shkiya'' depending on the time of year.<ref>Dvar Yom Chap. 6:21</ref>
####In New York this ''shiur'' results in the end of ''Shabbat'' ranging from 41 - 52 minutes after ''shkiya,'' depending on the time of year.<ref>Dvar Yom Chap. 6:21</ref>
##72 minutes fixed.<ref>Dvar Yom Chap. 6:25-31. He writes that there are many questions on the 72-minute fixed ''shiur.'' 1. It is not equally dark in all locations at all times. 2. In other areas of halacha it is not necessarily accepted that the amount of a ''mil'' is 18 minutes. If so, why are we automatically accepting that a ''mil'' is 72 minutes. Also, there are many that hold that ''tzet'' is 5 ''mil'' after ''shkiya''? He answers that since the real time for ''tzet'' is when the stars come out; therefore, the whole impetus to wait 72 minutes is really a stringency. This stringency was not accepted to its fullest. It was only accepted up until 72 fixed minutes.</ref><ref>See Hazmanim B'Halacha Chap. 44-46 that the author Rav Chaim Beinish who, at length, posits that the ''minhag'' of various places around the world of when to end ''Shabbat'' coincides with their geopraphic location. In short, he shows how places that were farther north generally went in accordance with Rabbenu Tam to wait 72 minutes. Places farther south went in accordance with the ''geonim.'' And places in between went after the ''minhag'' of 3 stars. (His goal is to prove that ultimately everyone agrees that ''tzet hakochavim'' si when 3 stars are visible.)</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-23T19:45:13Z

Schwartz: /* Bein HaShemashot and Tzet Hakochavim */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Distance of Mil===

#
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Time period of Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Some consider a ''mil'' to be 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
### Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
### Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
### There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref name=":0">Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref name=":1">Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''
*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear.</ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref name=":2">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref name=":3">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref name=":4">Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref name=":5">Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref name=":6">Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref name=":7">Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref name=":8">Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref name=":9">Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot and Tzet Hakochavim===

#The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day and after which it is night.<ref>Gemara Shabbat 34b. There is a dispute there between Rabbi Yehuda Rabbi Nechemia and Rabbi Yosi. Rabbi Yehuda says that ''bein hasmashot'' begins when the sun (''lit.)'' sinks and lasts until the upper part of the eastern sky is dark. Rabbi Nechemia says that ''bein hashmashot'' starts when the sun sinks and lasts for the duration of 0.5 ''mil.'' Rabbi Yosi says that ''bein hasmashot'' lasts for "a blink of an eye". Gemara Shabbat 35b quotes Rav Yehuda in the name of Shmuel that when there is one star it is still day, two stars is ''bein hashmashot'', three stars is night. Gemara Shabbat 35a writes that the halacha is in accordance with both Rabbi Yehuda and Rabbi Yosi. Rif Shabbat Chap.2, Rosh Shabbat Chap 2:23, and others maintain that the halacha follows Shmuel as well.
*These are the bases for the discussion amongst the ''poskim'' as to the time of ''bein hashmashot''. To see how this translates into the common halacha and for a full discussion see Hazmanim B'halacha Chap. 40</ref><ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot|bein hashemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot|bein hashemashot]]? Rabbi Yehuda says that [[Bein HaShemashot|bein hashemashot]] starts from [[Shekiyah]] when the eastern horizon darkens, and concludes 3/4 of a ''mil'' later when the upper part of the sky becomes dark as well. Rabbi Yosi says that [[Bein HaShemashot|bein hashemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.''<ref>Ginzei Kedem V pg.37, See Teshuvat Maharam Alshakar 96 quoting Teshuvat Rav Sherira Goan and Rav Hai Goan. For a more complete list see Hazmanim B'halacha - Rav Benish Chap. 41 3-5.
*Notably, Gra O.C. 261:11, Y.D. 262:9, and Rav Shneur Zalman of Liadi (Baal HaTanya) Siddur - Seder HaChnosat Shabbat, ''pasken'' in accordance with this view and it has thus become accepted halacha in most circles.

*Notable exceptions to this were Rav Yoel Teitelbaum of Satmar and Rav Yekusiel Yehuda Halberstam of Tzanz-Klausenburg who wrote that the halacha is in accordance with Rabbenu Tam. See Divrei Yoel 18, Shefa Chaim - Kovetz Igros Kodesh I:11-20

*Hazmanim B'halacha Chap.44:5 writes that regarding the start of Shabbat even the Satmar Rav and the Tzanz-Klausenburger Rav went in accordance with the ''geonim.''
*Igrot Moshe IV:62 writes that we are not able to resolve a dispute between ''rishonim'' and we must be stringent according to both views.</ref> Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.<ref>Sefer HaYashar New Edition 221, Tosfot Shabbat 35a ''s.v''. trei, Tosfot Pesachim 94a ''s.v.'' Rabbi Yehudah. Many other ''rishonim'' agreed with Rabbenu Tam, see Hazmanim B'halacha Chap 42:6-10 for a complete list.</ref><ref>There are additional opinions as well; yet they are not the accepted halacha.
*Sefer Yeraim 274 writes that ''bein hashmashos'' begins 0.75 ''mil'' before sunset and lasts until sunset at which time it is night. Biur Halacha 261:2 ''s.v. mitchilas'' writes that it is worthwhile to start ''Shabbat'' before that time.

*Sefer Raavan 2 writes that ''bein hashmashot'' begins at sunset and lasts 5 ''mil'' until ''tzet hakochavim.''

*See Hazmanim B'halacha Chap 41 for a complete discussion.</ref><ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Biur Halacha 261:2 ''s.v. kodem'' writes that it varies according to one's location.</ref>
#Just as by ''alot hashachar'', there is a dispute among the ''poskim'' as to the value of a ''mil'' and the amount of ''mil'' between ''alot'' and ''hanetz'', so too, this dispute applies regarding ''tzet hakochavim.''
#Similarly, just as by ''alot'' there is a dispute as to whether the time is measured in degrees, ''shaot shavot,'' or ''shaot zmaniot''; that dispute applies regarding ''tzet hakochavim'' as well.<ref>There are three methods in the ''poskim'' for applying the ''zman'' of the Gra and of Rabbenu Tam: degrees, ''shaot zmaniot, shaot shavot.''
*Degrees - The time of ''tzet hakochavim'' is an astronomical event; the timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''tzet'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. ''Tzet'' is always when the sun is at a certain point below the horizon. According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''tzet'' occurs 72 minutes after sunset, they do not mean to say that ''tzet'' occurs 72 minutes after ''shkiya'' in every locale, on every day of the year. Rather, they are discussing the time of ''tzet'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.

*The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
*The following applies assuming that a ''mil'' is either 18, 22.5, or 24 minutes.

*According to the Gra the following times apply

*At 13 1/2 minutes the sun is 3.7º below the horizon.

*At 16 7/8 minutes the sun is 4.4º below the horizon.

*At 18 minutes the sun is 4.7º below the horizon.

*According to Rabbenu Tam the degrees would be the following.

*At 72 minutes the sun is 16.1º below the horizon.

*At 90 minutes the sun is 19.75º below the horizon.

*At 120 minutes the sun is 25.9º below the horizon.

*Shaot Zmaniot

*Some hold that the times given are the actual times for ''tzet''; yet they are not measured in terms of a 60-minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes. Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' the following way: 72 minutes = 96 minutes and 13.5 minutes = 18 minutes.

*Fixed Minutes

*Some hold that ''tzet'' is determined by fixed minutes.</ref>
#Because of all these factors, there are different customs as to the time of ''bein hashmashot'' and ''tzet hakochvim.''
#Nowadays there is a widespread ''minhag'' to start ''bein hashmashot'' at ''shkiya'' in accordance with the ''zman'' of the ''geonim.''<ref>Hazmanim B'halacha Chap 44:5. He mentions that even those who were vehement in upholding the ''minhag'' to go in accordance with Rabbenu Tam agreed to be stringent to stop all ''melacha'' on ''Erev Shabbat'' at ''shkiya.'' </ref>
#Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.<ref>Minchas Kohen 2:5 ''s.v.'' ''she'im'', Biur Halacha 261:2 ''s.v. kodem'' and Igros Moshe O.C. IV:62 agree. Rav Moshe writes that in New York the time for ''tzet'' according to Rabbenu Tam is 50 minutes after ''shkiya''; however, he writes that it is proper for G-d fearing Jews to wait 72 minutes to end Shabbat, as was the custom in Europe. See Hazmanim B'halacha Chap. 42 for a complete discussion.</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-23T13:39:40Z

Schwartz: /* Bein HaShemashot and Tzet Hakochavim */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Distance of Mil===

#
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Time period of Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Some consider a ''mil'' to be 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
### Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
### Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
### There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref name=":0">Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref name=":1">Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''
*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear.</ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref name=":2">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref name=":3">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref name=":4">Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref name=":5">Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref name=":6">Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref name=":7">Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref name=":8">Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref name=":9">Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot and Tzet Hakochavim===

#The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day and after which it is night.<ref>Gemara Shabbat 34b. There is a dispute there between Rabbi Yehuda Rabbi Nechemia and Rabbi Yosi. Rabbi Yehuda says that ''bein hasmashot'' begins when the sun (''lit.)'' sinks and lasts until the upper part of the eastern sky is dark. Rabbi Nechemia says that ''bein hashmashot'' starts when the sun sinks and lasts for the duration of 0.5 ''mil.'' Rabbi Yosi says that ''bein hasmashot'' lasts for "a blink of an eye". Gemara Shabbat 35b quotes Rav Yehuda in the name of Shmuel that when there is one star it is still day, two stars is ''bein hashmashot'', three stars is night. Gemara Shabbat 35a writes that the halacha is in accordance with both Rabbi Yehuda and Rabbi Yosi. Rif Shabbat Chap.2, Rosh Shabbat Chap 2:23, and others maintain that the halacha follows Shmuel as well.
*These are the bases for the discussion amongst the ''poskim'' as to the time of ''bein hashmashot''. To see how this translates into the common halacha and for a full discussion see Hazmanim B'halacha Chap. 40</ref><ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot|bein hashemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot|bein hashemashot]]? Rabbi Yehuda says that [[Bein HaShemashot|bein hashemashot]] starts from [[Shekiyah]] when the eastern horizon darkens, and concludes 3/4 of a ''mil'' later when the upper part of the sky becomes dark as well. Rabbi Yosi says that [[Bein HaShemashot|bein hashemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.''<ref>Ginzei Kedem V pg.37, See Teshuvat Maharam Alshakar 96 quoting Teshuvat Rav Sherira Goan and Rav Hai Goan. For a more complete list see Hazmanim B'halacha - Rav Benish Chap. 41 3-5.
*Notably, Gra O.C. 261:11, Y.D. 262:9, and Rav Shneur Zalman of Liadi (Baal HaTanya) Siddur - Seder HaChnosat Shabbat, ''pasken'' in accordance with this view and it has thus become accepted halacha in most circles.

*Notable exceptions to this were Rav Yoel Teitelbaum of Satmar and Rav Yekusiel Yehuda Halberstam of Tzanz-Klausenburg who wrote that the halacha is in accordance with Rabbenu Tam. See Divrei Yoel 18, Shefa Chaim - Kovetz Igros Kodesh I:11-20

*Hazmanim B'halacha Chap.44:5 writes that regarding the start of Shabbat even the Satmar Rav and the Tzanz-Klausenburger Rav went in accordance with the ''geonim.''
*Igrot Moshe IV:62 writes that we are not able to resolve a dispute between ''rishonim'' and we must be stringent according to both views.</ref> Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.<ref>Sefer HaYashar New Edition 221, Tosfot Shabbat 35a ''s.v''. trei, Tosfot Pesachim 94a ''s.v.'' Rabbi Yehudah. Many other ''rishonim'' agreed with Rabbenu Tam, see Hazmanim B'halacha Chap 42:6-10 for a complete list.</ref><ref>There are additional opinions as well; yet they are not the accepted halacha.
*Sefer Yeraim 274 writes that ''bein hashmashos'' begins 0.75 ''mil'' before sunset and lasts until sunset at which time it is night. Biur Halacha 261:2 ''s.v. mitchilas'' writes that it is worthwhile to start ''Shabbat'' before that time.

*Sefer Raavan 2 writes that ''bein hashmashot'' begins at sunset and lasts 5 ''mil'' until ''tzet hakochavim.''

*See Hazmanim B'halacha Chap 41 for a complete discussion.</ref><ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Biur Halacha 261:2 ''s.v. kodem'' writes that it varies according to one's location.</ref>
#Just as by ''alot hashachar'', there is a dispute among the ''poskim'' as to the value of a ''mil'' and the amount of ''mil'' between ''alot'' and ''hanetz'', so too, this dispute applies regarding ''tzet hakochavim.''
#Similarly, just as by ''alot'' there is a dispute as to whether the time is measured in degrees, ''shaot shavot,'' or ''shaot zmaniot''; that dispute applies regarding ''tzet hakochavim'' as well.<ref>There are three methods in the ''poskim'' for applying the ''zman'' of the Gra and of Rabbenu Tam: degrees, ''shaot zmaniot, shaot shavot.''
*Degrees - The time of ''tzet hakochavim'' is an astronomical event; the timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''tzet'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. ''Tzet'' is always when the sun is at a certain point below the horizon. According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''tzet'' occurs 72 minutes after sunset, they do not mean to say that ''tzet'' occurs 72 minutes after ''shkiya'' in every locale, on every day of the year. Rather, they are discussing the time of ''tzet'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.

*The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
*The following applies assuming that a ''mil'' is either 18, 22.5, or 24 minutes.

*According to the Gra the following times apply

*At 13 1/2 minutes the sun is 3.7º below the horizon.

*At 16 7/8 minutes the sun is 4.4º below the horizon.

*At 18 minutes the sun is 4.7º below the horizon.

*According to Rabbenu Tam the degrees would be the following.

*At 72 minutes the sun is 16.1º below the horizon.

*At 90 minutes the sun is 19.75º below the horizon.

*At 120 minutes the sun is 25.9º below the horizon.

*Shaot Zmaniot

*Some hold that the times given are the actual times for ''tzet''; yet they are not measured in terms of a 60-minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes. Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' the following way: 72 minutes = 96 minutes and 13.5 minutes = 18 minutes.

*Fixed Minutes

*Some hold that ''tzet'' is determined by fixed minutes.</ref>
#Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.<ref>Minchas Kohen 2:5 ''s.v.'' ''she'im'', Biur Halacha 261:2 ''s.v. kodem'' and Igros Moshe O.C. IV:62 agree. Rav Moshe writes that in New York the time for ''tzet'' according to Rabbenu Tam is 50 minutes after ''shkiya''; however, he writes that it is proper for G-d fearing Jews to wait 72 minutes to end Shabbat, as was the custom in Europe. See Hazmanim B'halacha Chap. 42 for a complete discussion.</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T20:56:15Z

Schwartz: /* Bein HaShemashot and Tzet Hakochavim */ Still in middle of this footnote...

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Distance of Mil===

#
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Time period of Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Some consider a ''mil'' to be 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
### Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
### Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
### There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref name=":0">Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref name=":1">Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''
*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear.</ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref name=":2">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref name=":3">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref name=":4">Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref name=":5">Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref name=":6">Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref name=":7">Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref name=":8">Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref name=":9">Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot and Tzet Hakochavim===

#The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day and after which it is night.<ref>Gemara Shabbat 34b. There is a dispute there between Rabbi Yehuda Rabbi Nechemia and Rabbi Yosi. Rabbi Yehuda says that ''bein hasmashot'' begins when the sun (''lit.)'' sinks and lasts until the upper part of the eastern sky is dark. Rabbi Nechemia says that ''bein hashmashot'' starts when the sun sinks and lasts for the duration of 0.5 ''mil.'' Rabbi Yosi says that ''bein hasmashot'' lasts for "a blink of an eye". Gemara Shabbat 35b quotes Rav Yehuda in the name of Shmuel that when there is one star it is still day, two stars is ''bein hashmashot'', three stars is night. Gemara Shabbat 35a writes that the halacha is in accordance with both Rabbi Yehuda and Rabbi Yosi. Rif Shabbat Chap.2, Rosh Shabbat Chap 2:23, and others maintain that the halacha follows Shmuel as well.
*These are the bases for the discussion amongst the ''poskim'' as to the time of ''bein hashmashot''. To see how this translates into the common halacha and for a full discussion see Hazmanim B'halacha Chap. 40</ref><ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot|bein hashemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot|bein hashemashot]]? Rabbi Yehuda says that [[Bein HaShemashot|bein hashemashot]] starts from [[Shekiyah]] when the eastern horizon darkens, and concludes 3/4 of a ''mil'' later when the upper part of the sky becomes dark as well. Rabbi Yosi says that [[Bein HaShemashot|bein hashemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.''<ref>Ginzei Kedem V pg.37, See Teshuvat Maharam Alshakar 96 quoting Teshuvat Rav Sherira Goan and Rav Hai Goan. For a more complete list see Hazmanim B'halacha - Rav Benish Chap. 41 3-5.
*Notably, Gra O.C. 261:11, Y.D. 262:9, and Rav Shneur Zalman of Liadi (Baal HaTanya) Siddur - Seder HaChnosat Shabbat, ''pasken'' in accordance with this view and it has thus become accepted halacha in most circles.

*Notable exceptions to this were Rav Yoel Teitelbaum of Satmar and Rav Yekusiel Yehuda Halberstam of Tzanz-Klausenburg who wrote that the halacha is in accordance with Rabbenu Tam. See Divrei Yoel 18, Shefa Chaim - Kovetz Igros Kodesh I:11-20

*Hazmanim B'halacha Chap.44:5 writes that regarding the start of Shabbat even the Satmar Rav and the Tzanz-Klausenburger Rav went in accordance with the ''geonim.''
*Igrot Moshe IV:62 writes that we are not able to resolve a dispute between ''rishonim'' and we must be stringent according to both views.</ref> Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.<ref>Sefer HaYashar New Edition 221, Tosfot Shabbat 35a ''s.v''. trei, Tosfot Pesachim 94a ''s.v.'' Rabbi Yehudah. Many other ''rishonim'' agreed with Rabbenu Tam, see Hazmanim B'halacha Chap 42:6-10 for a complete list.</ref><ref>There are additional opinions as well; yet they are not the accepted halacha.
*Sefer Yeraim 274 writes that ''bein hashmashos'' begins 0.75 ''mil'' before sunset and lasts until sunset at which time it is night. Biur Halacha 261:2 ''s.v. mitchilas'' writes that it is worthwhile to start ''Shabbat'' before that time.

*Sefer Raavan 2 writes that ''bein hashmashot'' begins at sunset and lasts 5 ''mil'' until ''tzet hakochavim.''

*See Hazmanim B'halacha Chap 41 for a complete discussion.</ref><ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Biur Halacha 261:2 ''s.v. kodem'' writes that it varies according to one's location.</ref>
#Just as by ''alot hashachar'', there is a dispute among the ''poskim'' as to the value of a ''mil'' and the amount of ''mil'' between ''alot'' and ''hanetz'', so too, this dispute applies regarding ''tzet hakochavim.''
#Similarly, just as by ''alot'' there is a dispute as to whether the time is measured in degrees, ''shaot shavot,'' or ''shaot zmaniot''; that dispute applies regarding ''tzet hakochavim'' as well.<ref>There are three methods in the ''poskim'' for applying the ''zman'' of the Gra and of Rabbenu Tam: degrees, ''shaot zmaniot, shaot shavot.''
*Degrees - The time of ''tzet hakochavim'' is an astronomical event; the timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''tzet'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. ''Tzet'' is always when the sun is at a certain point below the horizon. According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''tzet'' occurs 72 minutes after sunset, they do not mean to say that ''tzet'' occurs 72 minutes after ''shkiya'' in every locale, on every day of the year. Rather, they are discussing the time of ''tzet'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.

*The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
*The following applies assuming that a ''mil'' is either 18, 22.5, or 24 minutes.

*According to the Gra the following times apply

*At 13 1/2 minutes the sun is 3.7º below the horizon.

*At 16 7/8 minutes the sun is 4.4º below the horizon.

* At 18 minutes the sun is 4.7º below the horizon.

*According to Rabbenu Tam the degrees would be the following.

*At 72 minutes the sun is 16.1º below the horizon.

* At 90 minutes the sun is 19.75º below the horizon.

* At 120 minutes the sun is 25.9º below the horizon.

Shaot Zmaniot

Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes. Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:

120 minutes = 160 minutes

90 minutes = 120 minutes

72 minutes = 96 minutes

Fixed Minutes

Some hold that ''alot'' is determined by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:

120 minutes fixed before Netz.

90 minutes fixed before Netz.

72 minutes fixed before Netz.</ref>
#Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.<ref>Minchas Kohen 2:5 ''s.v.'' ''she'im'', Biur Halacha 261:2 ''s.v. kodem'' and Igros Moshe O.C. IV:62 agree. Rav Moshe writes that in New York the time for ''tzet'' according to Rabbenu Tam is 50 minutes after ''shkiya''; however, he writes that it is proper for G-d fearing Jews to wait 72 minutes to end Shabbat, as was the custom in Europe. See Hazmanim B'halacha Chap. 42 for a complete discussion.</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T20:46:40Z

Schwartz: /* Fixed Minutes */ I am working on consolidating this. I do not want to place all that was written for alot in the body, instead I will put it in the footnote. The reason is because there are very few who go with Rabbenu Tam for degrees. There are a few explanations for this. On top I'll write a few accepted views and on the bottom I'll explain.

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Distance of Mil===

#
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Time period of Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Some consider a ''mil'' to be 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
### Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
### Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
### There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref name=":0">Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref name=":1">Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''
*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear.</ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref name=":2">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref name=":3">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref name=":4">Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref name=":5">Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref name=":6">Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref name=":7">Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref name=":8">Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref name=":9">Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot and Tzet Hakochavim===

#The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day and after which it is night.<ref>Gemara Shabbat 34b. There is a dispute there between Rabbi Yehuda Rabbi Nechemia and Rabbi Yosi. Rabbi Yehuda says that ''bein hasmashot'' begins when the sun (''lit.)'' sinks and lasts until the upper part of the eastern sky is dark. Rabbi Nechemia says that ''bein hashmashot'' starts when the sun sinks and lasts for the duration of 0.5 ''mil.'' Rabbi Yosi says that ''bein hasmashot'' lasts for "a blink of an eye". Gemara Shabbat 35b quotes Rav Yehuda in the name of Shmuel that when there is one star it is still day, two stars is ''bein hashmashot'', three stars is night. Gemara Shabbat 35a writes that the halacha is in accordance with both Rabbi Yehuda and Rabbi Yosi. Rif Shabbat Chap.2, Rosh Shabbat Chap 2:23, and others maintain that the halacha follows Shmuel as well.
*These are the bases for the discussion amongst the ''poskim'' as to the time of ''bein hashmashot''. To see how this translates into the common halacha and for a full discussion see Hazmanim B'halacha Chap. 40</ref><ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot|bein hashemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot|bein hashemashot]]? Rabbi Yehuda says that [[Bein HaShemashot|bein hashemashot]] starts from [[Shekiyah]] when the eastern horizon darkens, and concludes 3/4 of a ''mil'' later when the upper part of the sky becomes dark as well. Rabbi Yosi says that [[Bein HaShemashot|bein hashemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.''<ref>Ginzei Kedem V pg.37, See Teshuvat Maharam Alshakar 96 quoting Teshuvat Rav Sherira Goan and Rav Hai Goan. For a more complete list see Hazmanim B'halacha - Rav Benish Chap. 41 3-5.
*Notably, Gra O.C. 261:11, Y.D. 262:9, and Rav Shneur Zalman of Liadi (Baal HaTanya) Siddur - Seder HaChnosat Shabbat, ''pasken'' in accordance with this view and it has thus become accepted halacha in most circles.

*Notable exceptions to this were Rav Yoel Teitelbaum of Satmar and Rav Yekusiel Yehuda Halberstam of Tzanz-Klausenburg who wrote that the halacha is in accordance with Rabbenu Tam. See Divrei Yoel 18, Shefa Chaim - Kovetz Igros Kodesh I:11-20

*Hazmanim B'halacha Chap.44:5 writes that regarding the start of Shabbat even the Satmar Rav and the Tzanz-Klausenburger Rav went in accordance with the ''geonim.''
*Igrot Moshe IV:62 writes that we are not able to resolve a dispute between ''rishonim'' and we must be stringent according to both views.</ref> Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.<ref>Sefer HaYashar New Edition 221, Tosfot Shabbat 35a ''s.v''. trei, Tosfot Pesachim 94a ''s.v.'' Rabbi Yehudah. Many other ''rishonim'' agreed with Rabbenu Tam, see Hazmanim B'halacha Chap 42:6-10 for a complete list.</ref><ref>There are additional opinions as well; yet they are not the accepted halacha.
*Sefer Yeraim 274 writes that ''bein hashmashos'' begins 0.75 ''mil'' before sunset and lasts until sunset at which time it is night. Biur Halacha 261:2 ''s.v. mitchilas'' writes that it is worthwhile to start ''Shabbat'' before that time.

*Sefer Raavan 2 writes that ''bein hashmashot'' begins at sunset and lasts 5 ''mil'' until ''tzet hakochavim.''

*See Hazmanim B'halacha Chap 41 for a complete discussion.</ref><ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Biur Halacha 261:2 ''s.v. kodem'' writes that it varies according to one's location.</ref>
#Just as by ''alot hashachar'', there is a dispute among the ''poskim'' as to the value of a ''mil'' and the amount of ''mil'' between ''alot'' and ''hanetz'', so too, this dispute applies regarding ''tzet hakochavim.''
#Similarly, just as by ''alot'' there is a dispute as to whether it is measured in degrees, ''shaot shavot,'' or ''shaot zmaniot''; there is the same dispute regarding ''tzet hakochavim'' as well.
#Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.<ref>Minchas Kohen 2:5 ''s.v.'' ''she'im'', Biur Halacha 261:2 ''s.v. kodem'' and Igros Moshe O.C. IV:62 agree. Rav Moshe writes that in New York the time for ''tzet'' according to Rabbenu Tam is 50 minutes after ''shkiya''; however, he writes that it is proper for G-d fearing Jews to wait 72 minutes to end Shabbat, as was the custom in Europe. See Hazmanim B'halacha Chap. 42 for a complete discussion.</ref><ref>There are three methods in the ''poskim'' for applying the ''zman'' of the Gra and of Rabbenu Tam: degrees, ''shaot zmaniot, shaot shavot.''

*Degrees - The time of ''tzet hakochavim'' is an astronomical event; the timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''tzet'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. ''Tzet'' is always when the sun is at a certain point below the horizon. According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''tzet'' occurs 72 minutes after sunset they do not mean to say that ''tzet'' occurs 72 minutes after ''shkiya'' in every locale, on every day of the year. Rather, they are discussing the time of ''tzet'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.

*The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)

At 72 minutes the sun is 16.1º below the horizon.

Shaot Zmaniot

Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes. Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:

120 minutes = 160 minutes

90 minutes = 120 minutes

72 minutes = 96 minutes

Fixed Minutes

Some hold that ''alot'' is determined by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:

120 minutes fixed before Netz.

90 minutes fixed before Netz.

72 minutes fixed before Netz.</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T19:41:50Z

Schwartz: /* Tzet HaKochavim (Emergence of the Stars) */ The same discussion which applies for alot applies for tzet. However, I think I will put it in the footnote because most who are strict to follow Rabbenu Tam are not strict to use shaaos zmaniot or degrees. I'm still thinking what to put in and what to take out....

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Distance of Mil===

#
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Time period of Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Some consider a ''mil'' to be 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
### Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
### Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
### There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref name=":0">Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref name=":1">Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''
*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear.</ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref name=":2">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref name=":3">Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref name=":4">Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref name=":5">Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref name=":6">Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref name=":7">Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref name=":8">Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref name=":9">Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot and Tzet Hakochavim===

#The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day and after which it is night.<ref>Gemara Shabbat 34b. There is a dispute there between Rabbi Yehuda Rabbi Nechemia and Rabbi Yosi. Rabbi Yehuda says that ''bein hasmashot'' begins when the sun (''lit.)'' sinks and lasts until the upper part of the eastern sky is dark. Rabbi Nechemia says that ''bein hashmashot'' starts when the sun sinks and lasts for the duration of 0.5 ''mil.'' Rabbi Yosi says that ''bein hasmashot'' lasts for "a blink of an eye". Gemara Shabbat 35b quotes Rav Yehuda in the name of Shmuel that when there is one star it is still day, two stars is ''bein hashmashot'', three stars is night. Gemara Shabbat 35a writes that the halacha is in accordance with both Rabbi Yehuda and Rabbi Yosi. Rif Shabbat Chap.2, Rosh Shabbat Chap 2:23, and others maintain that the halacha follows Shmuel as well.
*These are the bases for the discussion amongst the ''poskim'' as to the time of ''bein hashmashot''. To see how this translates into the common halacha and for a full discussion see Hazmanim B'halacha Chap. 40</ref><ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot|bein hashemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot|bein hashemashot]]? Rabbi Yehuda says that [[Bein HaShemashot|bein hashemashot]] starts from [[Shekiyah]] when the eastern horizon darkens, and concludes 3/4 of a ''mil'' later when the upper part of the sky becomes dark as well. Rabbi Yosi says that [[Bein HaShemashot|bein hashemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.''<ref>Ginzei Kedem V pg.37, See Teshuvat Maharam Alshakar 96 quoting Teshuvat Rav Sherira Goan and Rav Hai Goan. For a more complete list see Hazmanim B'halacha - Rav Benish Chap. 41 3-5.
*Notably, Gra O.C. 261:11, Y.D. 262:9, and Rav Shneur Zalman of Liadi (Baal HaTanya) Siddur - Seder HaChnosat Shabbat, ''pasken'' in accordance with this view and it has thus become accepted halacha in most circles.

*Notable exceptions to this were Rav Yoel Teitelbaum of Satmar and Rav Yekusiel Yehuda Halberstam of Tzanz-Klausenburg who wrote that the halacha is in accordance with Rabbenu Tam. See Divrei Yoel 18, Shefa Chaim - Kovetz Igros Kodesh I:11-20

*Hazmanim B'halacha Chap.44:5 writes that regarding the start of Shabbat even the Satmar Rav and the Tzanz-Klausenburger Rav went in accordance with the ''geonim.''
*Igrot Moshe IV:62 writes that we are not able to resolve a dispute between ''rishonim'' and we must be stringent according to both views.</ref> Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.<ref>Sefer HaYashar New Edition 221, Tosfot Shabbat 35a ''s.v''. trei, Tosfot Pesachim 94a ''s.v.'' Rabbi Yehudah. Many other ''rishonim'' agreed with Rabbenu Tam, see Hazmanim B'halacha Chap 42:6-10 for a complete list.</ref><ref>There are additional opinions as well; yet they are not the accepted halacha.
*Sefer Yeraim 274 writes that ''bein hashmashos'' begins 0.75 ''mil'' before sunset and lasts until sunset at which time it is night. Biur Halacha 261:2 ''s.v. mitchilas'' writes that it is worthwhile to start ''Shabbat'' before that time.

*Sefer Raavan 2 writes that ''bein hashmashot'' begins at sunset and lasts 5 ''mil'' until ''tzet hakochavim.''

*See Hazmanim B'halacha Chap 41 for a complete discussion.</ref>

==== Applying these Times ====
# There are three methods in the ''poskim'' for applying the ''zman'' of the Gra and of Rabbenu Tam: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref name=":0" /> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref name=":1" />
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref name=":2" />
##At 90 minutes the sun is 19.75º below the horizon.<ref name=":3" />
##At 72 minutes the sun is 16.1º below the horizon.<ref name=":4" />

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref name=":5" /> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref name=":6" /> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref name=":7" />
##90 minutes fixed before Netz.<ref name=":8" />
##72 minutes fixed before Netz.<ref name=":9" />
#Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.<ref>Minchas Kohen 2:5 ''s.v.'' ''she'im'', Biur Halacha 261:2 ''s.v. kodem'' and Igros Moshe O.C. IV:62 agree. Rav Moshe writes that in New York the time for ''tzet'' according to Rabbenu Tam is 50 minutes after ''shkiya''; however, he writes that it is proper for G-d fearing Jews to wait 72 minutes to end Shabbat, as was the custom in Europe. See Hazmanim B'halacha Chap. 42 for a complete discussion.</ref>
#The ''Gemara'' rules that if one does a ''melacha'' on [[Shabbos|''Shabbat'']] for the duration of ''bein hashemashot'' on Friday evening and Saturday evening, one has certainly violated [[Shabbos|''Shabbat'']], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform ''melacha'' during [[Bein Hashemashot|''bein hashemashot'']]. <ref>Mishnah [[Shabbos]] 34b </ref>

=== Tzet HaKochavim (Emergence of the Stars) ===

# There's a major dispute when ''tzet hakochavim'' is: Rabbenu Tam assumes that it's 4 ''mil'' after [[Shekiyah|''shekiyah'']], and the Gra assumes that it's three quarters of a [[mil|''mil'']] after [[Shekiyah|''shekiyah'']].<ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Biur Halacha 261:2 ''s.v. kodem'' writes that it varies according to one's location.</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T14:15:00Z

Schwartz: /* Bein HaShemashot */ This line is not so accurate and is written more clearly in the following line. I deleted it.

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Distance of Mil===

#
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Time period of Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Some consider a ''mil'' to be 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
### Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
### Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
### There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot===

#The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day and after which it is night.<ref>Gemara Shabbat 34b. There is a dispute there between Rabbi Yehuda Rabbi Nechemia and Rabbi Yosi. Rabbi Yehuda says that ''bein hasmashot'' begins when the sun (''lit.)'' sinks and lasts until the upper part of the eastern sky is dark. Rabbi Nechemia says that ''bein hashmashot'' starts when the sun sinks and lasts for the duration of 0.5 ''mil.'' Rabbi Yosi says that ''bein hasmashot'' lasts for "a blink of an eye". Gemara Shabbat 35b quotes Rav Yehuda in the name of Shmuel that when there is one star it is still day, two stars is ''bein hashmashot'', three stars is night. Gemara Shabbat 35a writes that the halacha is in accordance with both Rabbi Yehuda and Rabbi Yosi. Rif Shabbat Chap.2, Rosh Shabbat Chap 2:23, and others maintain that the halacha follows Shmuel as well.
*These are the bases for the discussion amongst the ''poskim'' as to the time of ''bein hashmashot''. To see how this translates into the common halacha and for a full discussion see Hazmanim B'halacha Chap. 40</ref><ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot|bein hashemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot|bein hashemashot]]? Rabbi Yehuda says that [[Bein HaShemashot|bein hashemashot]] starts from [[Shekiyah]] when the eastern horizon darkens, and concludes 3/4 of a ''mil'' later when the upper part of the sky becomes dark as well. Rabbi Yosi says that [[Bein HaShemashot|bein hashemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.''<ref>Ginzei Kedem V pg.37, See Teshuvat Maharam Alshakar 96 quoting Teshuvat Rav Sherira Goan and Rav Hai Goan. For a more complete list see Hazmanim B'halacha - Rav Benish Chap. 41 3-5.
*Notably, Gra O.C. 261:11, Y.D. 262:9, and Rav Shneur Zalman of Liadi (Baal HaTanya) Siddur - Seder HaChnosat Shabbat, ''pasken'' in accordance with this view and it has thus become accepted halacha in most circles.

*Notable exceptions to this were Rav Yoel Teitelbaum of Satmar and Rav Yekusiel Yehuda Halberstam of Tzanz-Klausenburg who wrote that the halacha is in accordance with Rabbenu Tam. See Divrei Yoel 18, Shefa Chaim - Kovetz Igros Kodesh I:11-20

*Hazmanim B'halacha Chap.44:5 writes that regarding the start of Shabbat even the Satmar Rav and the Tzanz-Klausenburger Rav went in accordance with the ''geonim.''
*Igrot Moshe IV:62 writes that we are not able to resolve a dispute between ''rishonim'' and we must be stringent according to both views.</ref> Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.<ref>Sefer HaYashar New Edition 221, Tosfot Shabbat 35a ''s.v''. trei, Tosfot Pesachim 94a ''s.v.'' Rabbi Yehudah. Many other ''rishonim'' agreed with Rabbenu Tam, see Hazmanim B'halacha Chap 42:6-10 for a complete list.</ref><ref>There are additional opinions as well; yet they are not the accepted halacha.
*Sefer Yeraim 274 writes that ''bein hashmashos'' begins 0.75 ''mil'' before sunset and lasts until sunset at which time it is night. Biur Halacha 261:2 ''s.v. mitchilas'' writes that it is worthwhile to start ''Shabbat'' before that time.

*Sefer Raavan 2 writes that ''bein hashmashot'' begins at sunset and lasts 5 ''mil'' until ''tzet hakochavim.''

*See Hazmanim B'halacha Chap 41 for a complete discussion.</ref>
#Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.<ref>Minchas Kohen 2:5 ''s.v.'' ''she'im'', Biur Halacha 261:2 ''s.v. kodem'' and Igros Moshe O.C. IV:62 agree. Rav Moshe writes that in New York the time for ''tzet'' according to Rabbenu Tam is 50 minutes after ''shkiya''; however, he writes that it is proper for G-d fearing Jews to wait 72 minutes to end Shabbat, as was the custom in Europe. See Hazmanim B'halacha Chap. 42 for a complete discussion.</ref>
#The ''Gemara'' rules that if one does a ''melacha'' on [[Shabbos|''Shabbat'']] for the duration of ''bein hashemashot'' on Friday evening and Saturday evening, one has certainly violated [[Shabbos|''Shabbat'']], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform ''melacha'' during [[Bein Hashemashot|''bein hashemashot'']]. <ref>Mishnah [[Shabbos]] 34b </ref>

=== Tzet HaKochavim (Emergence of the Stars) ===

# There's a major dispute when ''tzet hakochavim'' is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah|''shekiyah'']] and the Gra assumes that it's three quarters of a [[mil|''mil'']] after [[Shekiyah|''shekiyah'']], varying according to one's location.<ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T14:11:06Z

Schwartz: /* Bein HaShemashot */ I started going through this note. It said that acc. to R Yehuda bein hashmashot ends when the ball of the sun goes down. If this was my page I would take out this whole footnote. It needs a lot of clarification and I believe that it is not so important for the practical halacha. In other footnotes I wrote in a much more concise version what is needed for the page. Would you like for me to spend a few hours fixing this one up? or take it out?

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Distance of Mil===

#
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Time period of Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Some consider a ''mil'' to be 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
### Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
### Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
### There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot===

#[[Bein HaShemashot|''Bein hashemashot'']] is the time period between certain daytime and certain nighttime. It is considered a ''safek,'' or doubt, whether it is considered day or night; this has many halachic ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot|bein hashemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot|bein hashemashot]]? Rabbi Yehuda says that [[Bein HaShemashot|bein hashemashot]] starts from [[Shekiyah]] when the eastern horizon darkens, and concludes 3/4 of a ''mil'' later when the upper part of the sky becomes dark as well. Rabbi Yosi says that [[Bein HaShemashot|bein hashemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day and after which it is night.<ref>Gemara Shabbat 34b. There is a dispute there between Rabbi Yehuda Rabbi Nechemia and Rabbi Yosi. Rabbi Yehuda says that ''bein hasmashot'' begins when the sun (''lit.)'' sinks and lasts until the upper part of the eastern sky is dark. Rabbi Nechemia says that ''bein hashmashot'' starts when the sun sinks and lasts for the duration of 0.5 ''mil.'' Rabbi Yosi says that ''bein hasmashot'' lasts for "a blink of an eye". Gemara Shabbat 35b quotes Rav Yehuda in the name of Shmuel that when there is one star it is still day, two stars is ''bein hashmashot'', three stars is night. Gemara Shabbat 35a writes that the halacha is in accordance with both Rabbi Yehuda and Rabbi Yosi. Rif Shabbat Chap.2, Rosh Shabbat Chap 2:23, and others maintain that the halacha follows Shmuel as well.
*These are the bases for the discussion amongst the ''poskim'' as to the time of ''bein hashmashot''. To see how this translates into the common halacha and for a full discussion see Hazmanim B'halacha Chap. 40</ref>
#There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.''<ref>Ginzei Kedem V pg.37, See Teshuvat Maharam Alshakar 96 quoting Teshuvat Rav Sherira Goan and Rav Hai Goan. For a more complete list see Hazmanim B'halacha - Rav Benish Chap. 41 3-5.
*Notably, Gra O.C. 261:11, Y.D. 262:9, and Rav Shneur Zalman of Liadi (Baal HaTanya) Siddur - Seder HaChnosat Shabbat, ''pasken'' in accordance with this view and it has thus become accepted halacha in most circles.

*Notable exceptions to this were Rav Yoel Teitelbaum of Satmar and Rav Yekusiel Yehuda Halberstam of Tzanz-Klausenburg who wrote that the halacha is in accordance with Rabbenu Tam. See Divrei Yoel 18, Shefa Chaim - Kovetz Igros Kodesh I:11-20

*Hazmanim B'halacha Chap.44:5 writes that regarding the start of Shabbat even the Satmar Rav and the Tzanz-Klausenburger Rav went in accordance with the ''geonim.''
*Igrot Moshe IV:62 writes that we are not able to resolve a dispute between ''rishonim'' and we must be stringent according to both views.</ref> Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.<ref>Sefer HaYashar New Edition 221, Tosfot Shabbat 35a ''s.v''. trei, Tosfot Pesachim 94a ''s.v.'' Rabbi Yehudah. Many other ''rishonim'' agreed with Rabbenu Tam, see Hazmanim B'halacha Chap 42:6-10 for a complete list.</ref><ref>There are additional opinions as well; yet they are not the accepted halacha.
*Sefer Yeraim 274 writes that ''bein hashmashos'' begins 0.75 ''mil'' before sunset and lasts until sunset at which time it is night. Biur Halacha 261:2 ''s.v. mitchilas'' writes that it is worthwhile to start ''Shabbat'' before that time.

*Sefer Raavan 2 writes that ''bein hashmashot'' begins at sunset and lasts 5 ''mil'' until ''tzet hakochavim.''

*See Hazmanim B'halacha Chap 41 for a complete discussion.</ref>
#Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.<ref>Minchas Kohen 2:5 ''s.v.'' ''she'im'', Biur Halacha 261:2 ''s.v. kodem'' and Igros Moshe O.C. IV:62 agree. Rav Moshe writes that in New York the time for ''tzet'' according to Rabbenu Tam is 50 minutes after ''shkiya''; however, he writes that it is proper for G-d fearing Jews to wait 72 minutes to end Shabbat, as was the custom in Europe. See Hazmanim B'halacha Chap. 42 for a complete discussion.</ref>
#The ''Gemara'' rules that if one does a ''melacha'' on [[Shabbos|''Shabbat'']] for the duration of ''bein hashemashot'' on Friday evening and Saturday evening, one has certainly violated [[Shabbos|''Shabbat'']], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform ''melacha'' during [[Bein Hashemashot|''bein hashemashot'']]. <ref>Mishnah [[Shabbos]] 34b </ref>

=== Tzet HaKochavim (Emergence of the Stars) ===

# There's a major dispute when ''tzet hakochavim'' is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah|''shekiyah'']] and the Gra assumes that it's three quarters of a [[mil|''mil'']] after [[Shekiyah|''shekiyah'']], varying according to one's location.<ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T13:40:03Z

Schwartz: /* Bein HaShemashot */ First time i copy/pasted it came w/o footnotes. I redid it and it worked

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Distance of Mil===

#
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Time period of Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Some consider a ''mil'' to be 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
### Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
### Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
### There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot===

#[[Bein HaShemashot|''Bein hashemashot'']] is the time period between certain daytime and certain nighttime. It is considered a ''safek,'' or doubt, whether it is considered day or night; this has many halachic ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day and after which it is night.<ref>Gemara Shabbat 34b. There is a dispute there between Rabbi Yehuda Rabbi Nechemia and Rabbi Yosi. Rabbi Yehuda says that ''bein hasmashot'' begins when the sun (''lit.)'' sinks and lasts until the upper part of the eastern sky is dark. Rabbi Nechemia says that ''bein hashmashot'' starts when the sun sinks and lasts for the duration of 0.5 ''mil.'' Rabbi Yosi says that ''bein hasmashot'' lasts for "a blink of an eye". Gemara Shabbat 35b quotes Rav Yehuda in the name of Shmuel that when there is one star it is still day, two stars is ''bein hashmashot'', three stars is night. Gemara Shabbat 35a writes that the halacha is in accordance with both Rabbi Yehuda and Rabbi Yosi. Rif Shabbat Chap.2, Rosh Shabbat Chap 2:23, and others maintain that the halacha follows Shmuel as well.
*These are the bases for the discussion amongst the ''poskim'' as to the time of ''bein hashmashot''. To see how this translates into the common halacha and for a full discussion see Hazmanim B'halacha Chap. 40</ref>
#There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.''<ref>Ginzei Kedem V pg.37, See Teshuvat Maharam Alshakar 96 quoting Teshuvat Rav Sherira Goan and Rav Hai Goan. For a more complete list see Hazmanim B'halacha - Rav Benish Chap. 41 3-5.
*Notably, Gra O.C. 261:11, Y.D. 262:9, and Rav Shneur Zalman of Liadi (Baal HaTanya) Siddur - Seder HaChnosat Shabbat, ''pasken'' in accordance with this view and it has thus become accepted halacha in most circles.

*Notable exceptions to this were Rav Yoel Teitelbaum of Satmar and Rav Yekusiel Yehuda Halberstam of Tzanz-Klausenburg who wrote that the halacha is in accordance with Rabbenu Tam. See Divrei Yoel 18, Shefa Chaim - Kovetz Igros Kodesh I:11-20

*Hazmanim B'halacha Chap.44:5 writes that regarding the start of Shabbat even the Satmar Rav and the Tzanz-Klausenburger Rav went in accordance with the ''geonim.''
*Igrot Moshe IV:62 writes that we are not able to resolve a dispute between ''rishonim'' and we must be stringent according to both views.</ref> Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.<ref>Sefer HaYashar New Edition 221, Tosfot Shabbat 35a ''s.v''. trei, Tosfot Pesachim 94a ''s.v.'' Rabbi Yehudah. Many other ''rishonim'' agreed with Rabbenu Tam, see Hazmanim B'halacha Chap 42:6-10 for a complete list.</ref><ref>There are additional opinions as well; yet they are not the accepted halacha.
*Sefer Yeraim 274 writes that ''bein hashmashos'' begins 0.75 ''mil'' before sunset and lasts until sunset at which time it is night. Biur Halacha 261:2 ''s.v. mitchilas'' writes that it is worthwhile to start ''Shabbat'' before that time.

*Sefer Raavan 2 writes that ''bein hashmashot'' begins at sunset and lasts 5 ''mil'' until ''tzet hakochavim.''

*See Hazmanim B'halacha Chap 41 for a complete discussion.</ref>
#Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.<ref>Minchas Kohen 2:5 ''s.v.'' ''she'im'', Biur Halacha 261:2 ''s.v. kodem'' and Igros Moshe O.C. IV:62 agree. Rav Moshe writes that in New York the time for ''tzet'' according to Rabbenu Tam is 50 minutes after ''shkiya''; however, he writes that it is proper for G-d fearing Jews to wait 72 minutes to end Shabbat, as was the custom in Europe. See Hazmanim B'halacha Chap. 42 for a complete discussion.</ref>
#The ''Gemara'' rules that if one does a ''melacha'' on [[Shabbos|''Shabbat'']] for the duration of ''bein hashemashot'' on Friday evening and Saturday evening, one has certainly violated [[Shabbos|''Shabbat'']], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform ''melacha'' during [[Bein Hashemashot|''bein hashemashot'']]. <ref>Mishnah [[Shabbos]] 34b </ref>

=== Tzet HaKochavim (Emergence of the Stars) ===

# There's a major dispute when ''tzet hakochavim'' is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah|''shekiyah'']] and the Gra assumes that it's three quarters of a [[mil|''mil'']] after [[Shekiyah|''shekiyah'']], varying according to one's location.<ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T13:36:04Z

Schwartz: /* Bein HaShemashot */ I pasted here what was written in the Earliest time to pray page (I think that page should be renamed "Times of Prayer")

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Distance of Mil===

#
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Time period of Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Some consider a ''mil'' to be 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
### Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
### Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
### There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot===

#[[Bein HaShemashot|''Bein hashemashot'']] is the time period between certain daytime and certain nighttime. It is considered a ''safek,'' or doubt, whether it is considered day or night; this has many halachic ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
# The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day, and after which it is night.
# There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.'' Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.
# Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.
#The ''Gemara'' rules that if one does a ''melacha'' on [[Shabbos|''Shabbat'']] for the duration of ''bein hashemashot'' on Friday evening and Saturday evening, one has certainly violated [[Shabbos|''Shabbat'']], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform ''melacha'' during [[Bein Hashemashot|''bein hashemashot'']]. <ref>Mishnah [[Shabbos]] 34b </ref>

=== Tzet HaKochavim (Emergence of the Stars) ===

# There's a major dispute when ''tzet hakochavim'' is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah|''shekiyah'']] and the Gra assumes that it's three quarters of a [[mil|''mil'']] after [[Shekiyah|''shekiyah'']], varying according to one's location.<ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

When Is the Earliest and Latest Time to Pray?

2024-07-22T13:32:08Z

Schwartz: /* Birchot Hashachar */

*Note: For exact times for your location, see [http://www.myzmanim.com/search.aspx myzmanim.com].

==Earliest Times for Shacharit==
=== Korbanot ===
#One should recite [[Korbanot|''korbanot'']] during the day, meaning after [[Olot HaShachar|''alot ha'shachar'']].<ref>Shulchan Aruch O.C. 1:6 </ref>
#If one does not have time, according to Ashkenazim he may say ''korbanot'' at night.<ref>Pri Megadim M"Z 1:6, Mishna Brurah 1:17. Chida (Birkei Yosef 1:13) writes that a person who doesn't have time can say korbanot at night since it is no worse than learning Torah at night. However, he concludes, that according to kabbalah that a person shouldn't read psukim at night really he shouldn't recite korbanot then. </ref> In cases of need, such as a worker who needs to ''daven'' early, according to Sephardim, he can say ''[[korbanot]]'' from 96 seasonal minutes before [[HaNetz|''hanetz'']].<ref>Halacha Brurah 1:16 (based on Sh”t Yacheve Daat 2:8) writes that in cases of need (for example a worker who needs to daven early) it is possible to say [[korbanot]] 96 minutes before [[HaNetz|hanetz]].</ref>
#The ''parsha'' of the ''korban tamid'' and the ''mishnayot'' of the ''korbanot'' should only be said during the day.<ref>Shulchan Aruch O.C. 47:13, Mishna Brurah 47:32</ref>

=== Birchot Hashachar ===
#The earliest time to say [[Birchot HaShachar|''birchot hashachar'']] is from [[Chatzot|''chatzot'']] (halachic midnight).<ref>Magen Avraham 47:13, Kaf HaChaim 46:49, Or Letzion (vol 2, 4:9) </ref> Initially, one should say ''hanoten lesechvi vinah'' after ''alot hashachar''. However, if one did say it after ''chatzos'', they fulfilled their obligation.<ref>Rosh (Teshuva 4:1) writes that initially one shouldn't say Hamotzei Lesechvi until Olot. Shulchan Aruch 47:13 codifies this. Magen Avraham 47:13 cites the Arizal who says that all of the brachot can be said after Chatzot but the Magen Avraham qualifies this to where one actually heard the rooster crow. Either way he concludes that it is better to be strict to wait until olot. Mishna Brurah 47:31, Biur Halacha 47:13, and Peninei Halacha (Tefillah 9:5) agree. </ref>

=== Psukei Dzimra ===
#''Baruch sheamar'' should be said after [[Olot HaShachar|''alot hachachar'']] before [[HaNetz|''hanetz'']].<ref>Halacha Brurah 1:16 </ref> Others hold that it may be said before ''alot hashachar.''<ref>Leket Hakemach Hachadash 51:9, Ishei Yisrael (16:15, fnt. 48). Both Leket Hakemach Hachadash and Ishei Yisrael cite Daat Torah 664 and 58:1 who proves from Rashi Brachot 11b that psukei dzimra can be recited before the time for shema.</ref>

=== Tallit and Tefillin ===
#The earliest time that one should put on [[Tallit|''tallit'']] is [[MeSheYakir|''misheyakir'']]''[[HaNetz|.]]''<ref>Shulchan Aruch O.C. 18:3. Shulchan Aruch 18:3 rules that the time to make the bracha on [[Tallit]] is from ''[[MeSheYakir|mesheyakir]]''. There is a dispute among the achronim about when exactly [[MeSheYakir|''mesheyakir'']] is. Because of [[Safek Brachot LeHakel]], Halacha Brurah 18:6 one may not make the bracha earlier than a fifth of an hour (in [[Shaot Zmaniot]]) after [[Olot HaShachar|alot hashachar]]. See Rama 18:3 that one may make a bracha at alot hashachar. Mishna Brurah 18:10 writes that although one should be stringent like the Shulchan Aruch; however, one should not stop someone who does like the Rama. Aruch Hashulchan 18:9 rules according to Rama. The Mishna Brurah adds that even for one who follows the Rama should wait with the bracha until [[MeSheYakir|''mesheyakir'']]. He adds that one who makes a bracha, even at night, need not make another one because there are rishonim who hold that one can make the bracha at night.</ref> Ashkenazim, if they must, may put on ''tallit'' as early as ''alot hashachar''; yet they should not make a ''bracha'' until ''[[MeSheYakir|misheyakir]].''<ref>Rama O.C. 18:3, Mishna Brurah 18:10, Piskei Teshuvot 30:1 </ref> When making the ''bracha'', one should feel the ''tzitzit.''<ref>Rama O.C. 18:3</ref> If one already made a ''bracha'' they should not repeat it, even if they made it before ''alot hashachar''.<ref>Mishna Brurah 18:10</ref>
#The earliest time that one should lay ''tefillin is [[MeSheYakir|misheyakir]].''<ref>Shulchan Aruch O.C. 30:1</ref>
#One who is in a pressing situation and must ''daven'' before the ''zman -'' for if he does not, he will totally miss ''zman tefillah'', may put on ''tallit'' and ''tefillin'' before [[Alot HaShachar|''alot hashachar'']].<ref>Shulchan Aruch O.C. 30:3, Mishna Brurah 30:13, Ishei Yisrael 18:11</ref>
##If one puts on ''tzitzit'' before [[Alot HaShachar|''alot hashachar'']], he should not recite a ''bracha'' until [[MeSheYakir|''misheyakir'']], and then he should feel the ''tzitzit'' after making the ''bracha''.<ref>Shulchan Aruch and Rama O.C. 18:3</ref>
##If one makes this ''bracha'' during ''pesukei dezimra'', it should be said between paragraphs.<ref>Mishna Brurah 51:8 writes that it is permissible to say birchat hodaah during pesukei d'zimra. Shulchan Aruch O.C. 53:3 is clear that one can make a bracha on tallit and tefillin during pesukei d'zimra. Biur Halacha 51:4 s.v. Tzarich writes that it is better to wait for between paragraphs. Here too, there is no rush. Ishei Yisrael (16:6,7; ibid. 18:10,11) agrees.</ref> If [[MeSheYakir|''misheyakir'']] happens between the end of ''pesukei d'zimra'' and ''yishtabach'', one should wait to make the ''bracha'' until after ''[[yishtabach]]''.<ref>Shulchan Aruch O.C. 53:3</ref> However, the ''shliach tzibbur'' should make the ''bracha'' before ''yishtabach''.<ref>Rama O.C. 53:3. Mishna Brurah 53:8 writes that if he only gets the tallit and tefillin after yishtabach he may make the bracha at that time as well. It would be the same here if the time of misheyakir is during yishtabach. </ref> Once the ''shaliach tzibbur'' starts the ''kaddish'' after ''yishtabach'' one can no longer make a ''bracha'' on the ''tallit'' until after ''shemoneh esrei''.<ref>Rama O.C. 54:3; Mishna Brurah 54:13</ref> The ''bracha'' on ''tefillin'' may be said between the paragraphs of ''birchot kriat shema''.<ref>Shulchan Aruch and Rama O.C. 66:2, Mishna Brurah 54:13, Ishei Yisrael 18:11</ref>

=== Shema and Shemoneh Esrei ===
#The ''bracha'' of ''yotzer ohr'' may not be said before ''[[MeSheYakir|misheyakir]]''.<ref>Mishna Brurah 58:17. Piskei Teshuvot (58:10) notes that some are lenient when it is unavoidable. However, Biur Halakha (s.v. Zeman Kriat Shema) notes that this discussion may be irrelevant for men if they are going to only say Pesukei D’zimra before misheyakir and say the bracha on Tzitzit and Tefillin before Yotzer Or, and certainly it is preferable to not begin davening until one can make the bracha on Tzitzit and Tefillin.</ref> If one is ''davening'' before [[MeSheYakir|''misheyakir'']] he should say ''krias shema'' with the ''brachot'', skip over the ''bracha'' of ''yotzer ohr'', and say it after ''shemoneh esrei'', in the proper ''zman.''<ref>Ishai Yisrael 18:10</ref> One who accidentally said ''yotzer ohr'' before [[MeSheYakir|''misheyakir'']] should not repeat it.<ref>Biur Halacha 58:4 s.v. b'lo</ref>
#One who will be unable to recite ''shema'' after [[MeSheYakir|''misheyakir'']] may do so from ''[[Alot HaShachar|alot hashachar]]''.<ref>Shulchan Aruch O.C. 58:3</ref>
#''Shemoneh esrei'' should be recited after ''hanetz.''<ref>Shulchan Aruch 89:1</ref> If it was recited from [[Alot HaShachar|''alot hashachar'']] one has fulfilled his obligation. In a case of need, like for one who is traveling, it is even considered ideal to say ''shemoneh esrei'' from [[Alot HaShachar|''alot hashachar'']].<ref>The Rosh ([[Brachot]] 4:1) writes that even though ideally one should pray at [[HaNetz]] (sunrise) if one prayed after [[Olot HaShachar]] one would have fulfilled one’s obligation. This is also the opinion of many Rishonim including Tosfot 30a (s.v. Avuha), Rambam ([[Tefillah]] 3:7, Sh”t Rambam 27), Rabbenu Yerucham (according to Bet Yosef 89:1) and the Tur 89:1. This is codified in Shulchan Aruch 89:1. Mishna Berura 89:4 writes that if one has a pressing need, he may daven l'chatchila from alot hashachar.</ref>
# The ideal mitzvah is to start praying [[Shmoneh Esrei|''shmoneh esrei'']] of [[Shacharit|''shacharit'']] at ''ha[[Netz HaChama|netz hachama]]'' (sunrise). The practice of those who say ''shemoneh esrei'' of ''shacharit'' at ''[[HaNetz|hanetz]]'' is called ''Vatikin''.<ref>Shulchan Aruch O.C. 89:1, Shulchan Aruch O.C. 58:1, Gemara <nowiki>[[Brachot]]</nowiki> 26a writes the ideal time to pray <nowiki>[[Shacharit]]</nowiki> is at <nowiki>[[HaNetz HaChama]]</nowiki> and that was the practice of the <nowiki>[[Vatikin]]</nowiki> (those who fulfill the מצות early and in the proper time). This is codified by the Rambam (<nowiki>[[Tefillah]]</nowiki> 3:1), Rosh (<nowiki>[[Brachot]]</nowiki> 4:1), Tur and Shulchan Aruch 89:1</ref>
# If a person can either daven at ''[[HaNetz|hanetz]]'' without a minyan or later with a minyan, according to Ashkenazim one may daven at ''[[HaNetz|hanetz]]'' if one is always careful to ''daven'' at ''[[HaNetz|hanetz]]''.<ref>Biur Halacha 58:1 s.v. u'mitzva</ref> According to Sephardim one should daven with a minyan later unless one will pray with ''kavana''.<ref>Yalkut Yosef 89:19</ref>

== One Who Must Work Early ==
#If one needs to travel or in a case of difficulty one may pray [[Shacharit|''shacharit'']] after ''[[Olot HaShachar|alot hashachar]]'' before [[HaNetz|hanetz]], but nonetheless one may not make the ''bracha'' on [[Tallit|''tallit'']] and [[Tefillin|''tefillin'']] or say [[Kriyat Shema|''kriyat shema'']] until [[MeSheYakir|''misheyakir'']]. <ref>*The Rosh (Brachot 4:1) writes that even though ideally one should pray at [[HaNetz|hanetz]] (sunrise) if one prayed after [[Olot HaShachar|alot hashachar]] one would have fulfilled one’s obligation. This is also the opinion of many rishonim including Tosfot 30a (s.v. Avuha), Rambam ([[Tefillah]] 3:7, Sh”t Rambam 27), Rabbeinu Yerucham (according to Bet Yosef 89:1) and the Tur 89:1. This is codified in Shulchan Aruch 89:1.
*There is a minority of Rishonim who hold that in extenuating circumstances one is permitted to pray [[Shacharit]] before [[Olot HaShachar|alot hashachar]]. The basis of this approach is Rashi (Brachot 30a s.v. VeLayaved), Sh”t Raavan (176), and Raavad (quoted by the Sefer Hashlamah).
*Shulchan Aruch 89:8 rules that in cases of extenuating circumstances such as where one has to travel early one may pray [[Shacharit]] [[Shmoneh Esrei|shemoneh esrei]] immediately after [[Olot HaShachar|alot hashachar]] and then say Shema while traveling if one is able to have kavana (proper intent) while traveling. This is also mentioned in Mishna Brurah 89:1.</ref>
##Therefore, a person who needs to pray early in the morning in order to get to work should pray with a [[minyan|''minyan'']] that starts ''davening'' after ''misheyakir'' before ''[[HaNetz|hanetz]]''.<ref>Shulchan Aruch 89:1, Mishna Berurah 89:4 write that when in a pressing situation, one may daven shemoneh esrei from alot hashachar. Shulchan Aruch 18:3 writes that the bracha on tallit should not be said before misheyakir. Shulchan Aruch 30:1 writes that tefillin should not be laid before misheyakir. Shulchan Aruch 58:1 writes that krias shema should not be recited before misheyakir. </ref>
##If that isn't possible then the minyan should use the following schedule: say up to ''birchot [[Kriyat Shema|kriyat shema]]'' without [[Tallit|''tallit'']] and [[Tefillin|''tefillin'']] (except for ''shaliach tzibbur'' who should put on [[Tallit|''tallit'']] and [[Tefillin|''tefillin'']] before ''yishtabach''), when [[MeSheYakir|''misheyakir'']] arrives put on [[Tallit|''tallit'']] and [[Tefillin|''tefillin'']], then continue from there. <ref>[http://www.ou.org/webcast_kosher Rabbi Yisrael Belsky] (OU Kosher Webcast, min 19:30-28:30). Sh"t Igrot Moshe 4:6 writes that a person who needs to make it to work is considered to be in an extenuating circumstance in which Shulchan Aruch 89:8 writes that one may pray [[Shacharit]] after Alot Hashachar See also Iggrot Moshe OC 1:10 and Yechave Daat 2:8.</ref>
#If the choice is to ''daven'' with an early [[minyan|''minyan'']] that ''davens'' before ''[[HaNetz|hanetz]]'' after ''[[MeSheyakir|misheyakir]]'' or to ''daven'' later by oneself, such as in one's office, one should rather ''daven'' earlier with a [[minyan|''minyan'']].<ref>[http://www.ou.org/webcast_kosher Rabbi Yisrael Belsky] (OU Kosher Webcast, min 19:30-28:30), Igrot Moshe 4:6 s.v. im ken, Peri Yitzchak 1:2, Sh"t Yaskil Avdi 5:10, Sh"t Minchat Yitzchak 9:10. Chazon Ish (Ishei Yisrael 13:note 21) ruled likewise. [http://www.ou.org/webcast_kosher Rabbi Yisrael Belsky] (OU Kosher Webcast, min 19:30-28:30) said that if one feels that it is just too dark and one cannot understand what the people are relying on to put on [[Tefillin]] so early one should say up to Baruch SheAmar before traveling and then pray at one’s office.</ref> Some disagree and say that you should ''daven'' on your own rather than ''daven'' before ''hanetz''. <ref>Sh”t Sheilot Shmuel OC 12, Rav Elyashiv (quoted in Avnei Yashfei [[Tefillah]] page 167), Yalkut Yosef ([[Tefilla]] pages 137-139, 89:14). </ref>
#If a person who is not in a rush to ''daven'' before sunrise is needed for a [[minyan|''minyan'']] that is ''davening'' before sunrise there is a dispute whether he is allowed to join or not. <ref>Rav Yosef Shalom Elyashiv quoted in Tefilla Kehilchita page 78 and in Avnei Yashfe (Tefilla page 169 89:14) says that although he can answer for their [[minyan]] he cannot pray with them. This is true even if he is the sixth one who would be praying (a [[minyan]] requires ten but a minimum of six praying at the time) and his refusal to pray would prevent there being a [[minyan]]. Rav Shlomo Zalman Auerbach in Halichot Shlomo 1:5-13 (and Avnei Yishfe p. 169) though ruled that if the refusal to join will prevent the [[minyan]] he may pray with them as long as it is not on a consistent basis. </ref>

===Pre-Misheyakir===

#One who has a choice to ''daven'' with a pre-''[[MeSheyakir|misheyakir]]'' minyan or afterwards by himself, should ''daven'' alone.<ref>Avnei Yishfe p. 167 quotes Rav Elyashiv that it is better to daven oneself later rather than davening before Mesheyakir. He also cites Pri Yitzchak s.v. nachzor 1:2 who agrees.</ref> Some disagree.<ref>Avnei Yishfe p. 168 quotes Rav Ben Tzion Abba Shaul who says that if that's the only minyan available one should daven with a pre-mesheyakir minyan relying on the Pri Chadash rather than daven by oneself. Igrot Moshe 4:6 s.v. im ken agrees.</ref>

===After the Fact===

#If one ''davened'' before [[Olot HaShachar|''alot hashachar'']], one has not fulfilled their obligation. Nonetheless, one should ''daven'' again on condition that if one is exempt then they are ''davening'' voluntarily. <ref>*What is the earliest time for [[Shacharit]]? The Rosh 4:1 writes that even though ideally one should pray at [[HaNetz|hanetz]] (sunrise) if one prayed after [[Olot HaShachar|alot hashachar]] one would have fulfilled one’s obligation. This is also the opinion of many rishonim including Tosfot 30a (s.v. Avuha), Rambam ([[Tefillah]] 3:7, Sh”t Rambam 27), Rabbeinu Yerucham (according to Bet Yosef 89:1) and the Tur 89:1. This is codified in Shulchan Aruch 89:1.
*There is a minority of rishonim who hold that in extenuating circumstances one is permitted to pray [[Shacharit]] before [[Olot HaShachar|alot hashachar]]. The basis of this approach is Rashi ([[Brachot]] 30a s.v. VeLayaved), Sh”t Raavan (176), and Raavad (quoted by the Sefer Hashlamah).
*[Interestingly, the Derisha argues that Rabbeinu Yerucham holds that there are three levels, ideally one should pray at [[HaNetz|hanetz]], it is permissible to pray after [[MeSheYakir|misheyakir]] and it is only effective, after the fact, after [[Olot HaShachar|alot hashachar]].]
*Mishna Brurah 89:2 writes that based on Shulchan Aruch, if one prayed before [[Olot HaShachar|alot hashachar]] one has not fulfilled one’s obligation.
*Yalkut Yosef ([[Tefillah]] pg. 136, see also Sh”t Yechave Daat 2:8) writes that even if one prayed before [[Olot HaShachar|alot hashachar]] one should still pray again at the proper time with a stipulation that if one is not obligated that it should be a voluntary [[prayer]]. So writes Sh”t Otzrot Yosef 5:3.</ref>

== Latest Time for Shacharit ==
#The latest time to say [[Shmoneh Esrei|''shemoneh esrei'']] of [[Shacharit|''shacharit'']] is the end of the fourth hour. <ref>The Mishna (Brachot 26a) writes that the latest time [[Shacharit]] could be said according to Rabbi Yehuda is the fourth hour and according to the Rabbis is the sixth hour. The Gemara (27a) writes that we hold like Rabbi Yehuda because there is a Mishna in Ediyot that supports Rabbi Yehuda. This is codified by the Rif 18a, Rosh 4:1, and Rambam ([[Tefillah]] 3:1). The halacha is brought in Tur and Shulchan Aruch 89:1 </ref>
#If one has not ''davened'' until the end of the fourth hour, one should ''daven'' [[Shacharit|''shacharit'']] before the end of the sixth hour - midday. If one intentionally did not ''daven'' in the first four hours one should still ''daven'' before midday but one should stipulate that if one is exempt that one is ''davening'' a voluntary [[prayer]]. <ref>*The Rif 18a originates that even though we hold like Rabbi Yehuda that the latest time for [[Shacharit]] is the fourth hour one could still pray after the fourth hour and receive the reward for praying (albeit having lost the reward for praying in the proper time). The Rosh 4:1, Rambam (Hilchot [[Tefillah]] 3:1), and Tur 89:1 hold like the Rif.
*The Bet Yosef 89:1 writes that it seems as though the Rosh and Rif base their halacha on the general language of the gemara (Brachot 26a) “one could pray all day and receive reward for [[prayer]] but would lose the reward for [[prayer]] in its proper time.” Because this phrase was the gemara’s way of explaining the halacha of [[Tashlumin]], the Bet Yosef, rules that according to the Rif and Rosh one would not be able to pray after the fourth hour if a person intentionally did not pray in the first four hours.
*However, the Rambam and Tur 89:1 hold that if a person intentionally prayed after the fourth hour he still receives reward for [[prayer]]. The Bet Yosef 89:1 explains that the Rambam tried to minimize the dispute between רבנן and Rabbi Yehuda so that there would not be an argument as to whether one totally fulfills the mitzvah or does not fulfill it at all in the period between the fourth and sixth hour. Rather they both agree that it is still time for [[Shacharit]] but according to Rabbi Yehuda one who prays at that time only receives reward for [[prayer]] but not that of [[prayer]] in its proper time while רבנן hold that one would also receive the reward of it being in its proper time. According to this explanation, one should be able to pray in this period even if one intentionally did not pray beforehand.
*Additionally, if one holds like the Rif then one would be able to daven even between six and sixth and a half, while according to the Rambam one should only be able to pray as long as there is some opinion which considers it the time for [[Shacharit]]. The Bet Yosef adds that the Rashba agrees with the Rambam. (It seems that the Bet Yosef understands the Rashba to say that you certainly may not pray during the half hour after [[Chatzot]]. The Bach argues that the Rashba meant something else entirely, namely that one should pray the [[Tashlumin]] right after having prayed the obligatory [[Tefilla]].)
*The Mishna Brurah 89:6 writes that because of the dispute one should still pray after the fourth hour even if one intentionally missed praying earlier but nonetheless should stipulate that if one is exempt, one should be considered praying voluntarily. Yalkut Yosef 89:5 agrees.</ref>
#One may not ''daven'' past the end of the sixth hour, but rather one should wait to say [[Tashlumin|''tashlumin'']] at [[Mincha|''mincha'']].<ref>Rama O.C. 89:1 (based on the explanation of the Bet Yosef of the Rambam and Tur, see the [[#cite_note-11|previous footnote]])</ref>

==Times for Mincha==
===Ideal Time for Mincha===

#The ideal time to ''daven'' [[Mincha|''mincha'']] is after nine and a half hours ([[Mincha|''mincha'']] ''ketana''), however, one fulfills one’s obligation by ''davening'' from six and a half hours (''[[mincha]] gedola''). <ref>*Rambam (Tefillah 3:2) writes that since they instituted Tefillah corresponding to korbanot the primary time for mincha is mincha ketana, 9.5 hours in the day but one fulfills one's obligation anytime after mincha gedola, 6.5 hours. The Tur 233:1 argues that the primary time to pray [[Mincha]] is after six and a half hours since it is the time when a korban mincha is fit. Shulchan Aruch O.C. 233:1 follows the Rambam. The Mishna Brurah 233:1 also holds like the Rambam but adds that there are some rishonim who allow one to pray earlier and in certain cases (see further) one may pray earlier. Kaf HaChaim 233:1, Yalkut Yosef (Brachot page 637) and Halichot Olam (vol 1 pg 253) concur with Mishna Brurah. Aruch Hashulchan 233:12 writes that ideally one should daven after mincha ketana but for any small reason one could even initially daven mincha gedola.
*Kaf Hachaim 233:3 adds that really the best time is after plag mincha, 10.45 hours into the day.
*See the BeYitchak Yikra 233:1 (notes of Rav Nevinsal on Mishna Brurah) who adds that the Rambam holds that the only preferable time is after [[Mincha]] ketana before plag [[Mincha]] (10 ¾ hours) and it would be preferable to say [[Mincha]] individually at [[Mincha]] gedola rather than with a [[minyan]] at [[Mincha]] ketana after plag [[Mincha]]. Nonetheless, he agrees that the minhag is not like this.</ref>

====When it is Ideal to Daven Mincha Gedola====

#In many yeshivos the minhag is to ''daven'' ''mincha gedola'' to avoid breaking up a ''seder,'' a fixed section of learning.<ref>Piskei Teshuvot 233:2. [https://www.torahanytime.com/#/lectures?v=74381 Rav Yitzchak Yosef (Motzei Shabbat Shemot 5779 approx min 30)] explained that his father used to say mincha only after mincha ketana but later said it at mincha gedola. He recommended it for a yeshiva setting. He also explained that the Rif and Rosh hold that it is permitted even initially to say mincha at mincha gedola.</ref>
#If one needs to travel or have a meal (which is forbidden before ''davening'' once the time for [[Mincha|''mincha'']] arrives), one can ''daven'' from after six and a half hours. <ref>Mishna Brurah 233:1 writes that if one needs to travel, have a meal, or one will only be able to make a [[minyan]] for [[Mincha]] earlier, then one can pray from after six and a half hours. Kaf HaChaim 233:1 also writes that there are those who are lenient to pray early if there is a need. Yalkut Yosef ([[Brachot]] page 637) and Halichot Olam (vol 1 pg 253) writes that it is preferable to pray after six and a half hours in order to avoid having a meal before praying [[Mincha]] (after the time for [[Mincha]] has arrived). </ref>
#If one will only be able to make a [[minyan|''minyan'']] for ''[[mincha]] gedola'' (after six and a half hours) and one will not make a [[minyan|''minyan'']] for ''mincha ketana'' (after nine and a half hours), it is preferable to ''daven'' with a [[minyan|''minyan'']] after six and a half hours. <ref>Mishna Brurah 233:1, Yalkut Yosef ([[Brachot]] pg 639). [https://www.torahanytime.com/#/lectures?v=74381 Rav Yitzchak Yosef (Motzei Shabbat Shemot 5779 min 43)] said that although the Shoel Vnishal held that it is better to daven by oneself than to daven at mincha gedola the halacha doesn't follow that opinion.</ref>

===Earliest Time===

#If one ''davened'' prior to six and a half hours, according to many, one has not fulfilled one’s obligation; however, some say that one has fulfilled one's obligation after the fact. Therefore, one should not ''daven'' again.<ref>Mishna Brurah 233:2 writes that it is implied from Shulchan Aruch 233:1 that one has not fulfilled one's obligation (and is agreed upon by many achronim); however, there are some achronim who say that after the fact one has fulfilled one’s obligation. Kaf HaChaim 233:2 quotes the dispute of the achronim but concludes that because [[Tefillah]] is derabbanan one does not have to pray again. Ishei Yisrael 27:5 agrees. See Ishei Yisrael 27 footnote 10. </ref>

===Latest Time for Mincha===

==== After Plag HaMincha ====

# According to Rabbi Yehuda, the latest time for ''mincha'' is ''plag hamincha -'' ten- and three-quarter hours. From then on begins the time for ''arvit''. According to Rabbanan, the cutoff point is nightfall.<ref name=":0" /> Halacha allows one to follow either opinion, however, one must be consistent and always follow the same opinion.<ref name=":1" /> Thus, one who is accustomed to ''davening arvit'' before ''shkiya'' must always ''daven mincha'' before ''plag.''<ref>Shulchan Aruch O.C. 233:1, Rama O.C. 233:1</ref> In extenuating circumstances or if one forgot to ''daven mincha'', they may ''daven'' after ''plag;''<ref>Rama O.C. 233:1</ref> however, they should be particular to ''daven arvit'' after ''tzet hakochavim'' on that night.<ref>Mishna Brurah 233:11,13</ref>
# Some write that, even according to Rabbanan, one must ''daven mincha'' before ''plag.<ref>Aruch Hashulchan O.C. 233:4-9</ref>'' This is not the accepted custom.

====After Sunset====

#One who ''davens arvit'' after ''tzet'' may ''daven mincha'' up until ''shkiya.''<ref>The time period of ''bein hashmashot'' may be considered day, thus, If one ''davens arvit'' after ''shkiya'' but before ''tzet'' it would present a contradiction. Igrot Moshe II:60 writes that it may not be a contradiction to ''daven arvit'' at a time when one would no longer ''daven mincha.'' Thus, he writes, that one may ''daven'' with a ''minyan'' that is ''davening arvit'' at that time, if that is his only opportunity to ''daven'' with a ''minyan.'' </ref>
#The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day and after which it is night.<ref>Gemara Shabbat 34b. There is a dispute there between Rabbi Yehuda Rabbi Nechemia and Rabbi Yosi. Rabbi Yehuda says that ''bein hasmashot'' begins when the sun (''lit.)'' sinks and lasts until the upper part of the eastern sky is dark. Rabbi Nechemia says that ''bein hashmashot'' starts when the sun sinks and lasts for the duration of 0.5 ''mil.'' Rabbi Yosi says that ''bein hasmashot'' lasts for "a blink of an eye". Gemara Shabbat 35b quotes Rav Yehuda in the name of Shmuel that when there is one star it is still day, two stars is ''bein hashmashot'', three stars is night. Gemara Shabbat 35a writes that the halacha is in accordance with both Rabbi Yehuda and Rabbi Yosi. Rif Shabbat Chap.2, Rosh Shabbat Chap 2:23, and others maintain that the halacha follows Shmuel as well.

*These are the bases for the discussion amongst the ''poskim'' as to the time of ''bein hashmashot''. To see how this translates into the common halacha and for a full discussion see Hazmanim B'halacha Chap. 40</ref>
#There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.''<ref>Ginzei Kedem V pg.37, See Teshuvat Maharam Alshakar 96 quoting Teshuvat Rav Sherira Goan and Rav Hai Goan. For a more complete list see Hazmanim B'halacha - Rav Benish Chap. 41 3-5.

*Notably, Gra O.C. 261:11, Y.D. 262:9, and Rav Shneur Zalman of Liadi (Baal HaTanya) Siddur - Seder HaChnosat Shabbat, ''pasken'' in accordance with this view and it has thus become accepted halacha in most circles.

*Notable exceptions to this were Rav Yoel Teitelbaum of Satmar and Rav Yekusiel Yehuda Halberstam of Tzanz-Klausenburg who wrote that the halacha is in accordance with Rabbenu Tam. See Divrei Yoel 18, Shefa Chaim - Kovetz Igros Kodesh I:11-20

*Hazmanim B'halacha Chap.44:5 writes that regarding the start of Shabbat even the Satmar Rav and the Tzanz-Klausenburger Rav went in accordance with the ''geonim.''
*Igrot Moshe IV:62 writes that we are not able to resolve a dispute between ''rishonim'' and we must be stringent according to both views.</ref> Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.<ref>Sefer HaYashar New Edition 221, Tosfot Shabbat 35a ''s.v''. trei, Tosfot Pesachim 94a ''s.v.'' Rabbi Yehudah. Many other ''rishonim'' agreed with Rabbenu Tam, see Hazmanim B'halacha Chap 42:6-10 for a complete list.</ref><ref>There are additional opinions as well; yet they are not the accepted halacha.

*Sefer Yeraim 274 writes that ''bein hashmashos'' begins 0.75 ''mil'' before sunset and lasts until sunset at which time it is night. Biur Halacha 261:2 ''s.v. mitchilas'' writes that it is worthwhile to start ''Shabbat'' before that time.

*Sefer Raavan 2 writes that ''bein hashmashot'' begins at sunset and lasts 5 ''mil'' until ''tzet hakochavim.''

*See Hazmanim B'halacha Chap 41 for a complete discussion.</ref>
#Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.<ref>Minchas Kohen 2:5 ''s.v.'' ''she'im'', Biur Halacha 261:2 ''s.v. kodem'' and Igros Moshe O.C. IV:62 agree. Rav Moshe writes that in New York the time for ''tzet'' according to Rabbenu Tam is 50 minutes after ''shkiya''; however, he writes that it is proper for G-d fearing Jews to wait 72 minutes to end Shabbat, as was the custom in Europe. See Hazmanim B'halacha Chap. 42 for a complete discussion.</ref>
#One must ''daven mincha'' during the daytime. Since ''bein hashmashot'' begins at sunset according to the ''geonim'', one should ''daven mincha'' before sunset. After the fact, opinions differ regarding how late one can still ''daven'', and at what point should instead say [[Tashlumin|''tashlumin'']] at [[Maariv|''maariv'']]. Factors that come into consideration include whether or not one can rely on Rabbenu Tam after the fact, and whether or not one may ''daven'' during ''bein hashmashot'', as it may still be day.<ref>Rav Nevinsal on Mishna Brurah 233:14 writes that someone who doesn't always follow Rabbenu Tam on ending Shabbat can not daven mincha after sunset even after the fact. Also, Avnei Darech 8:200 quotes Rav Shlomo Zalman Auerbach as holding that one may not daven mincha after sunset. [http://www.eretzhemdah.org/newsletterArticle.asp?lang=he&pageid=48&cat=1&newsletter=3705&article=7631 Bmarah Habazek 3:14] writes that one shouldn't daven after sunset and just daven tashlumin. [https://www.yeshiva.co/ask/58222 Rav Belsky] held that it is possible to daven up to 9 minutes after sunset based on Rav Moshe. See Igrot Moshe 1:24 who writes that one shouldn't pray mincha after sunset. See further Igrot Moshe 4:62. Piskei Teshuvot 233:8 writes that the Minhag in Eretz Yisrael is that one may lenient to Daven mincha during Bein Hashmashot (according to the opinion of the Ge'onim) which is up to 13 and one half minutes after shkia'ah.</ref><ref>To illustrate this point: Igrot Moshe IV:62 writes that the first nine minutes after ''shkiya'' are considered a ''sfek sfaika and'' regarding a ''bris milah'', we could consider the baby as born on the earlier day. The ''sfek sfaika'' is that maybe the halacha follows Rabbenu Tam, and even not, it may be day according to the ''geonim.'' (Rav Moshe calculates that ''tzet hakochavim'' of the ''geonim,'' in New York, is nine minutes after ''shkiya'').</ref>
#Many Chassidim maintain that it is optimal to ''daven'' ''mincha'' up until the ''bein hashmashot'' of Rabbenu Tam, which is 3.75 ''mil'' after ''shkiya''. There are some who hold that it is even optimal to ''daven'' during ''bein hashmashot'' of Rabbenu Tam.<ref>For a discussion on this see Piskei Teshuva 233:6-8.</ref>
#If one's only options are to either to ''daven'' ''mincha'' before sunset himself or to ''daven'' with a ''minyan'' after sunset, it will depend on if he is Ashkenazi or Sephardi. Ashkenazim hold that one should ''daven'' oneself on time before sunset,<ref>Mishna Brurah 233:14 writes that it is better to pray Mincha before shkiyah without a minyan than to pray with a minyan after shkiyah. In an extenuating circumstance he allows davening mincha until 3.25 mil after shekiya based on the Shulchan Aruch. [https://ph.yhb.org.il/02-24-04/#_te01ftn24_3 Peninei Halacha (Tefillah 24:4)] holds that one can follow the Mishna Brurah who is based on Rabbenu Tam and even though we do not follow Rabbenu Tam since many agree with him. However, Kuntres Seyda Lderech p. 39 quotes Chazon Ish that one should not daven mincha after sunset even in extenuating circumstances or after the fact. Dirshu 233:22 cites this as well from Ishrei Yosher (Nezikin n. 94). Rav Nevinsal on Mishna Brurah 233:14 writes that someone who doesn't always follow Rabbenu Tam on ending Shabbat can not daven mincha after sunset even after the fact. Also, Avnei Darech 8:200 quotes Rav Shlomo Zalman Auerbach as holding that one may not daven mincha after sunset. [http://www.eretzhemdah.org/newsletterArticle.asp?lang=he&pageid=48&cat=1&newsletter=3705&article=7631 Bmarah Habazek 3:14] writes that one shouldn't daven after sunset and just daven tashlumin. [https://www.yeshiva.co/ask/58222 Rav Belsky] held that it is possible to daven up to 9 minutes after sunset based on Rav Moshe. See Igrot Moshe 1:24 who writes that one shouldn't pray mincha after sunset. See further Igrot Moshe 4:62.</ref> while Sephardim hold that one can wait to ''daven'' with the ''minyan'' as long as it is within 13.5 minutes after sunset.<ref> Chacham Ben Zion Abba Shaul (cited in Ishei Yisroel page 296) and Chacham Ovadia Yosef (Yechave Daat 5:22) write that it is preferable to pray with a minyan as long as they are praying within the first thirteen and a half minutes after sunset. Rabbi Meir Mazuz in Bayit Neeman 1:25 p. 146 s.v. miyhu agrees even though we don't accept Rabbeinu Tam since this case is an minhag to pray during Ben Hashemashot. Yalkut Yosef 233:3 and Halacha Brurah 233:6 agree. </ref>

====Finishing After Sunset====

#Sephardic ''poskim'' hold that one can start ''mincha'' before sunset even if one knows that one will not finish until after sunset.<ref>Rav Hai Goan and Rav Sherira Goan in Teshuvot Hagoanim (Lik, 51) Yabia Omer OC 7:34 quoting the Geonim (Teshuva Mosafiya n. 51)</ref> Some Ashkenazic ''poskim'' agree,<ref>Aruch Hashulchan 110:5 based on Tosfot Brachot 7a s.v. shilmaleh</ref> while many disagree.<ref>Kuntres Seyda Lderech p. 39 quotes Chazon Ish that one should not start mincha before sunset if one knows that one will not finish until after sunset. He cites that this is like Mishna Brurah 89:1 that one can't start tefilla before the zman and finish after the zman. He cites that Rav Chaim Kanievsky, Rav Aryeh Leib Shteinmann, and Rav Nosson Geshtetner agreed. </ref>
#Initially, all of the ''shemoneh esrei'' and ''chazarat hashatz'' should be finished before sunset.<ref>Yabia Omer 7:34 in fnt., Halacha Brurah 233:6. Yalkut Yosef 233:3 implies this as well as he writes that if it is after sunset the congregation shouldn't skip chazarat hashatz; they should say it as long as it is still within 13.5 minutes from sunset. Although Chacham Ovadia (Yabia Omer 7:34) wrote that it is permitted even initially to pray after sunset during the ben hashemashot, in the footnote he implies otherwise. He writes that it is only for someone who didn't have a chance to pray earlier may pray then. This is also how Halacha Brurah 233:6 understands the opinion of his father that it is preferable (''mitzvah min hamuvchar)'' to pray before sunset. </ref>

===Tachanun===

#If one reaches ''tachanun'' during ''bein hashmashot,'' there is a debate amongst the ''poskim'' if it should be recited with ''nefillat apayim''.<ref>Mishnah Brura 131:16 states that the discussion of whether or not ''tachanun'' may be said at night refers to reciting it with ''nefillas apayim.'' Merely reciting the chapter may be done at night. Mishnah Brura 131:17 holds one should say it with ''nefillas apayim''. Rav Avigdor Neventzal in B’Yitzhak Yikareh on Mishna Brura (footnote to 131) quotes Rav Shlomo Zalman Auerbach who thinks one should not. </ref>
#If [[mincha|''mincha'']] lasts until after ''tzeit hakochavim'', [[tachanun|''tachanun'']] is not recited with ''nefillat apayim''.<ref>Kitzur Shulchan Aruch 69:8, Mishna Brurah 131:17. Mishnah Brura 131:16 writes that although ''tachanun'' is not said with ''nefillas apayim''; nevertheless, the ''mizmor'' of ''tachanun'' may be recited even after ''tzeit hakochavim.'' </ref>
#Some ''poskim'' write that even the ''mizmor'' of ''tachanun'' must not be said, even during ''bein hashmashot.''<ref>Kaf HaChaim 131:51,52</ref>

===If One Hears Kedusha of a Late Mincha Minyan===

#According to many authorities, one who ''davened'' ''arvit'' before nightfall, may answer ''kedusha'' to a ''minyan davening mincha.'' This applies even on Friday night.<ref>Magen Giborim 237:1, Amudei Esh 3:19, Yaskil Avdi 5:30, and Tiferet Adam 8 hold that even after saying [[maariv]] one may answer [[kedusha]] of a [[minyan]] saying [[mincha]] unlike the opinion of the Erech Shai 236, Yagel Yacov, and Aruch HaShulchan 232. Yismach Lev 16 writes that even on Friday night if one said [[maariv]] one may still answer [[kedusha]]. Sh"t Tzitz Eliezer 10:16 and Sh"t Yabia Omer 6:21 agree with the Yishmach lev.</ref>

==Times for Arvit (Maariv)==
===Earliest Time for Arvit (Plag Hamincha)===

#One who ''davened'' ''arvit'' prior to ten- and three-quarter hours has not fulfilled his obligation and must ''daven'' again.<ref>Mishna Brurah 233:10, Kaf HaChaim 233:11 as is implied by Shulchan Aruch 233:1 </ref>
#One who means to ''daven arvit'' after ''tzeit hakochavim'' but mistakenly ''davened'' from ''plag hamincha'', must ''daven'' again at the proper time.<ref>Gemara Brachot 27b writes that on Friday afternoon someone who made a mistake and said [[Arvit]] early thinking it was nighttime according to Abaye he would have to pray again. The Rabbenu Yonah 18b s.v. Rav explains that since one made a mistake and did not intend to pray [[Arvit]] early one does not fulfill one’s obligation. The Magen Avraham 263:26 and Mishna Brurah 263:55 agree that this halacha applies equally to a weeknight as to Friday night. </ref>

=== Ideal Time for Arvit (Tzet Hakochavim) ===
#[[Kriyat Shema|''Kriyat shema'']] must be recited after [[Tzet HaKochavim|''tzet hakochavim'']].<ref>Mishna Brachot 2a, Shulchan Aruch OC 235:1, Kitzur Shulchan Aruch 70:1</ref> Since ''kriyat shema'' is biblical, one should be vigilant to recite ''shema'' after ''tzet hakochavim'' of Rabbenu Tam.<ref>Mishna Brurah 235:4, Igrot Moshe YD 4:48:4</ref>
#Ideally, one should ''daven'' [[Arvit|''arvit'']] after [[Tzet HaKochavim|''tzet hakochavim'']];<ref>Mishna Brurah 233:9, Kitzur Shulchan Aruch 70:2</ref> however, the ''minhag'' of many places is to ''daven'' ''arvit'' immediately after sunset.<ref>Igrot Moshe II:60 writes that it may not be a contradiction to ''daven arvit'' at a time when one would no longer ''daven mincha.'' Thus, he writes, that one may ''daven'' with a ''minyan'' that is ''davening arvit'' at that time, if that is his only opportunity to ''daven'' with a ''minyan.'' Mishna Brurah 235:12 writes that fortunate is the person who can daven with a congregation after Tzet Hakochavim which is the correct time.</ref>
#Many are accustomed to ''davening'' ''mincha'' before ''shkiya'', taking a short break, and ''davening arvit'' after ''tzet'' of the ''geonim'' which can be as early as nine minutes after ''shkiya.''<ref>According to Igrot Moshe IV:62, see Ishei Yisrael Chap. 28 footnote 2</ref>
#A ''tzibur'' may ''daven'' both ''mincha'' and ''arvit'' between ''plag'' and ''shkiya'' if it will be too difficult to reconvene after everyone goes home.<ref>Mishna Brurah 233:11</ref>

===Arvit Before Sunset If One Davened Mincha Early===

#According to Rabbi Yehuda, the latest time for ''mincha'' is ten- and three-quarter hours. From then on begins the time for ''arvit''. According to Rabbanan, the cutoff point is nightfall.<ref name=":0">The Mishna ([[Brachot]] 26a) writes that according to Rabbi Yehuda one must pray [[Mincha]] prior to ten and three quarter hours while according to Rabbanan [[Mincha]] may be said until nighttime. Tosfot Brachot 27a s.v. Ta Shma writes that according to Rabbi Yehuda the earliest time to say ''arvit'' is ten- and three-quarter hours while according to Rabbanan the earliest time is nighttime. [This is also evident in the Gemara there (27a-b) and the upcoming Rishonim. The Maharsha (27a s.v. Tah Shma) asks why Tosfot needed to prove something which was so obvious from the Gemara.] </ref> Halacha allows one to follow either opinion, however, one must be consistent and always follow the same opinion.<ref name=":1">The Gemara (27a) writes that since there is no explicit ruling as to whom the halacha follows, one who follows Rabbi Yehuda has done properly and one who follows Rabbanan is correct too. Rabbeinu Yonah ([[Brachot]] 18b s.v. DeAved) writes that one must consistently follow the same opinion. This is also opinion of the Rosh ([[Brachot]] 4:3) quoting a Gaon. Additionally, the Kesef Mishna ([[Tefillah]] 3:4) says that this is implicit in the Rambam and furthermore that it is the simple explanation of the words of the Gemara. Tur and Shulchan Aruch 233:1 codify the opinion of Rabbeinu Yonah. </ref>
#The general ''minhag'' is to ''daven mincha'' until sunset. Accordingly, one may only begin to ''daven arvit'' after that time.<ref>Rabbenu Yona Brachot 18a s.v. tefillat, Mordechai Brachot IV:90 quoting Rav Hai Goan, and others write that nightfall refers to ''shkiya.'' Rambam (Hilchot Tefillah 3:4) writes this as well. See Hazemanim B'Halacha - Rav Benish Chap. 34:6 and footnotes 16-19.

*Rashi Brachot 26a s.v. Ad Chashecha according to Shaagat Aryeh 17, Ra'av Brachot 4:1, and others explain "nightfall" to be ''tzet hakochavim.'' See Zemanim B'Halachah - Rav Benish Chap 34:7 and footnotes 22-28.
*Rama O.C. 233:1 writes that according to the Rabbanan one may ''daven mincha'' until ''tzet hakochavim''.
*Shulchan Aruch O.C. 233:1 writes that the ''minhag'' is to ''daven mincha'' until ''shkiya'' and one may not ''daven arvit'' before ''shkiya''.
*Mishna Brurah 233:8,9,14 understands that Shulchan Aruch means the second ''shkiya'' and that Shulchan Aruch and Rama both agree that one may ''daven mincha'' up until Rabbenu Tam's ''bein hashmashot'' which is 3.25 ''mil'' after sunset. That which Shulchan Aruch and Rama write ''"shkiya"'' and "''tzet hakochavim"'' is not exact and means "almost up until that time." Mishna Brurah understands that the cutoff of the Rabbanan is ''tzet'' but since ''bein hashmashot'' is a time of ''safek'', one may not ''daven'' neither ''mincha'' nor ''arvit'' during that time. Thus, ''mincha'' must be recited before 3.25 ''mil'' after sunset and ''arvit'' must be recited after 4 ''mil''. However, the Mishna Brurah, quoting many ''poskim,'' see Shaar Hatziyun 233:18, writes that others argue on the Shulchan Aruch and Rama and according to them one must not ''daven mincha'' after ''shkiya.'' The Mishna Brurah 233:14 writes that one should be stringent in accordance with this view. Nevertheless, he adds that one who is under extreme duress may be lenient to ''daven'' until 3.25 ''mil'' after ''shkiya'', but should ''daven'' as early as possible so as not to enter into a ''safek shkiya''.
*Mishna Brurah 235:12 writes that it is optimal to ''daven arvit'' after ''tzet'' - earlier than that, during ''bein hashmashot,'' is a ''safek''. Biur Halacha 233:1 ''s.v. d'haynu'' writes that one who is ''davening'' ''mincha'' after ''shkiya'' should make a condition: if this is still the time for ''mincha'' then this ''tefilla'' will be for ''mincha'' and the next will be for ''arvit''; yet if it is now the time for ''arvit'', this ''tefillah'' will be ''arvit'' and the next one will be a ''tashlumin'' for ''mincha.''
*Aruch HaShulchan 233:6-9 writes that one who is able must ''daven mincha'' before ''plag''. One who is not able to ''daven'' then must be careful to ''daven'' before ''shkiya'', despite the fact that there are ''rishonim'' who say that one may ''daven'' until ''tzet''.
*Igrot Moshe I:24 writes in accordance with Mishna Brura that one should not ''daven mincha'' after ''shkiya'' unless under duress. Rav Moshe adds that in America the ''zman'' of Rabbenu Tam is certainly less than an hour after ''shkiya.'' Thus, taking ''bein hashmashot'' into account, the time for ''mincha'' cannot be later than 48 minutes after ''shkiya'', and possibly it is in fact earlier.
*Orchot Rabbeinu III pg. 225 quotes the Chazon Ish as saying that if one knows that he won't finish ''shemoneh esrei'' before ''shkiya'' then he should not start ''davening''; rather he should ''daven'' ''maariv shemoneh esrei'' twice as ''tashlumin.''
</ref> In extenuating circumstances, one may ''daven arvit'' before sunset if on that day he ''davened mincha'' before ''plag hamincha''. Although he usually follows the Rabbanan, it is considered as if on that day he followed Rabbi Yehuda.<ref>The Rabbenu Yonah (18b s.v. DeAved) writes that one should always follow Rabbanan (which was the minhag of his time and place) but nonetheless, after the fact if one prayed [[Arvit]] after Plag [[Mincha]] one has fulfilled one’s obligation. This is quoted in Bet Yosef 233:1 and codified in Shulchan Aruch O.C. 233:1. The Shulchan Aruch 233:1 rules that in extenuating circumstances one may pray [[Arvit]] before nighttime even though one always follows Rabbanan. Mishna Brurah 233:11 writes that this is only permissible if that day itself one already prayed [[Mincha]] prior to ten and three quarter hours.</ref>
#If the only minyan for ''arvit'' ''davens'' before sunset, after ''plag hamincha,'' one should daven with them<ref>The Biur Halacha 235:1 cites the Gra who held that it is better to daven privately on time rather than daven with the congregation early. However, in Shaar Hatziyun 235:16 he quotes the Derech Hachayim that if one prayed mincha before plag and the only option is to daven after plag maariv with a minyan or after tzeit without a minyan, it is better to daven with a minyan after plag. If he didn't daven ''mincha'' until after ''plag'', it is better to ''daven maariv'' oneself than to daven in a minyan before sunset and contradict oneself within one day.</ref> and repeat ''shema'' after ''tzet hakochavim''. Some say to skip ''birchot kriyat shema'' and recite them after ''tzet hakochavim'' with ''shema''.<ref>Rabbenu Yonah Brachot 1b writes that if the congregation is davening before the time for Shema one should daven with them even though he won't fulfill his obligation of ''shema'' and will have to repeat it later. He then quotes Rav Hai Goan who says that one should only say ''shema'' with them without kavana to fulfill one's obligation but skip birchot kriyat shema. The Shulchan Aruch OC 235:1 rules like the Rabbenu Yonah but the Mishna Brurah 235:12 mentions the practice of the Rav Hai Goan. Rav Moshe Feinstein in Igrot Moshe OC 2:60 agrees that one can follow either opinion whether to daven everything or just Shema without kavana and Shemona Esrei and then say Shema with Kriyat Shema with Brachot afterwards. He writes that one shouldn't follow the Gra unless one always does according to his opinion.</ref>
# Many say, that for Sephardim, ''plag'' is 1.25 hours before ''tzet hakochavim'' of the ''geonim -'' which is 13.5 minutes after ''shekiya.'' They should not follow the ''plag'' of the Gra; 1.25 hours before sunset.<ref>Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12) and Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. Thereby, the Sephardi Plag Mincha is generally between 10 and 20 minutes after the Gra plag. Yalkut Yosef (Shabbat 1-3, 5771 edition, pp. 143-146) writes that a person can pray arvit as early as plag mincha. However, he defines plag hamincha as 1.25 hours before tzet hakochavim of the geonim. The hours are calculated from olot to tzet of the geonim. He addresses that for kriyat shema in extenuating circumstances it is acceptable to rely upon the Gra zmanim, but not for the brachot of avrit because of safek brachot lhakel. Also, one can't light Shabbat candles before 1.25 hours before tzet of geonim. He rebuts an attack that we must follow the Gra zmanim since we light candles before plag of Rabbenu Tam. He answers that we follow the plag of the Ben Ish Chai which is 1.25 hours before tzet of the geonim but not the Gra's plag. on p. 144 he writes that it is a bracha levatala to pray avrit after plag of the Gra.
*See also [https://www.torahanytime.com/#/lectures?v=81670 Rav Yitzchak Yosef (Motzei Shabbat Pesach 5779 min 37)] who said that the schedules which print plag mincha 1.25 hours before shekiya (Gra) are causing Sephardim to say brachot levatalot when they daven arvit right after plag. Rather they need to daven after plag which is 1.25 hours before tzet. Tzet is only 20 minutes (13.5 zmaniyot minutes) so our plag is less than 20 minutes after their plag but starting arvit before then is a bracha levatala for Sephardim. They should print the plag according to Sephardim.
*See also [https://www.torahanytime.com/#/lectures?v=55391 Rav Yitzchak Yosef (Motzei Shabbat Bo 5778 min 25)] who said that it is a bracha levatala to daven Arvit after Plag of the Gra according to Rabbenu Tam and we are strict for Rabbenu Tam.
*[https://www.torahanytime.com/#/lectures?v=60107 Rav Yitzchak Yosef (Motzei Shabbat Emor 5778 min 28)] said that since the minhag is that we follow the geonim for zmanim, the minhag is to pray mincha before Plag of the geonim and arvit after Plag of the geonim, even though according to Rabbenu Tam it is a bracha levatala since it is day.</ref> Thereby, the Sephardi ''plag hamincha'' is generally between 10 and 20 minutes after the Gra ''plag''. See the [https://play.google.com/store/apps/details?id=net.calj.android CalJ App] for calculation of this ''zman''. Others say that even Sephardim can calculate ''plag hamincha'' according to the Gra.<ref>Kaf Hachaim 233:7, Halacha Brurah v. 14 teshuva 7. Halacha Brurah writes that there's no safek brachot to light candles after plag of the gra or daven arvit after that plag since that is the minhag and there's no safek brachot where there is a minhag. He rejects the position of Ben Ish Chai that we calculate from Olot to Tzet of Geonim because that is definitely not the view of the Geonim. Rather the Geonim would calculate their zmanim in accordance with Gra.</ref>

===Early Arvit on Friday Night===

#Regarding praying [[Arvit|''arvit'']] early on Friday night see [[Making early Shabbat|Making Early Shabbat]].

===Mincha/Arvit Between Plag and Sunset===

#An individual may not ''daven mincha'' after ''plag hamincha'' and ''arvit'' before sunset on the same day.<ref>Shulchan Aruch 233:1, Mishna Brurah 233:11</ref>
#A [[minyan|''minyan'']] may be lenient to ''daven'' both [[Mincha|''mincha'']] and [[Arvit|''arvit'']] between ''plag hamincha'' and sunset, even though it is a self-contradictory practice following both Rabbanan and Rabbi Yehuda.<ref>Mishna Brurah 233:11 writes that in a minyan where there is an excessive effort to get everyone back to shul for [[maariv]] (and people cannot wait in shul), it is permissible for a [[minyan]] to say [[maariv]] right after [[Mincha]] (between Plag [[Mincha]] and nighttime). Shulchan Aruch 233:1 says the minhag is like Rabbanan and Rama 233:1 says the minhag is like Rabbi Yehuda. Nowadays, Piskei Teshuvot 233:4 writes that the Ashkenazic minhag is also like Rabbanan. </ref> If the only ''minyan'' available is such a ''minyan,'' an individual should not join them for both ''mincha'' and ''maariv''.<ref>Mishna Brurah 235:14</ref> If one is needed to complete the ''minyan'' they may join.

===Maariv After Sunset Before Tzet===

#If one is ''davening'' with a ''minyan'' immediately after sunset one should ''daven'' with them completely and repeat ''shema'' after ''tzet''. Some have a practice to ''daven'' ''shema'' and ''shemoneh esrei'' together with the ''tzibbur'' while skipping ''birchot kriyat shema. Shema'' and the ''brachos'' are then repeated after tzet hakochavim.<ref>*The Rif (Brachot 1b) rules that the time to say [[Kriyat Shema]] at night is from [[Tzet HaKochavim]] like the simple Mishna and Gemara Brachot 2a. The Rambam (Kriyat Shema 1:9) concurs.
*Rashi (Brachot 2a s.v. Ad Sof) also holds that one does not fulfill Shema until [[Tzet HaKochavim]] but defends the practice to say Shema in Shul with the [[Brachot]] explaining that the Shema in Shul is only to precede [[Shmoneh Esrei]] with words of Torah, whereas the primary time one fulfills one's obligation of saying Shema is before going to sleep.
*Rabbenu Tam (quoted by Tosfot [[Brachot]] 2a s.v. Meeymatai) argues that really we hold like Rabbenu Yehuda in the Mishna (Brachot 26a) who says that one may say [[Arvit]] from Plag [[Mincha]], so too we hold that one may say Shema from Plag [[Mincha]]. The Ri (also quoted in the above Tosfot) agrees that the primary Shema is the one said in Shul, however, he explains that it is because we hold like the other opinions quoted in the Gemara 2a-b who say that the time for Shema is earlier than [[Tzet HaKochavim]].
*The Rosh (Brachot 1:1) rejects the Rabbenu Tam’s comparison between the time for [[Arvit]] and Shema and rather says that with difficulty one could defend the minhag like the Ri but nonetheless preferably one should say Shema only after [[Tzet HaKochavim]].
*The Rosh (Brachot 1:1) quotes the Rav Hai Goan who says that if one is in a situation where one could either pray with a [[minyan]] before [[Tzet HaKochavim]] or pray by oneself later one should pray with the [[minyan]] early but not say Shema with the [[Brachot]] until later. Rav Hai Goan also suggests that one could pray with the congregation as a voluntary [[prayer]] and then pray again oneself with Shema and [[Shmoneh Esrei]]. This is also quoted by the Rabbenu Yonah (Brachot 1b s.v. VeRabbenu Hai), Rashba (Brachot 2a s.v. VeNishal), and Tur 235:1.
*Rabbenu Yonah gives an alternative for someone in that situation; say [[Brachot]] of Shema, Shema with intent not to fulfill one’s obligation but rather just as words of Torah, and then [[Shmoneh Esrei]] with the [[minyan]] and after [[Tzet HaKochavim]] one should repeat Shema with the intent of fulfilling one's obligation.
*The Bet Yosef 235:1 concludes that one should make sure to repeat Shema after [[Tzet HaKochavim]] but one may follow the above suggestions (of Rav Hai and Rabbenu Yonah). Mishna Brurah 235:12 and Igrot Moshe 2:60 write that one can follow either Rav Hai or Rabbenu Yonah. The Shulchan Aruch 235:1 writes like the Rabbenu Yonah that if one is praying with a congregation earlier than [[Tzet HaKochavim]] one should say Shema with the [[Brachot]] and [[Shmoneh Esrei]] and then repeat Shema at [[Tzet HaKochavim]].
*The Mishna Brurah 235:9 writes like the Rabbenu Yonah that when saying Shema early one should not have intent to be fulfilling one’s obligation until [[Tzet HaKochavim]]. The Mishna Brurah 235:11 writes that it is a dispute whether one must repeat the third paragraph of Shema. Igrot Moshe 2:60 writes that one should repeat all three paragraphs.
*Igrot Moshe OC 2:60 explains that the reason that the Rabbenu Yonah and Mishna Brurah wrote not to have intent to fulfill one's obligation of kriyat Shema is because of a concern of [[Baal Tosif]]. If a person were to say Shema at the wrong time with intent that one should fulfill one's obligation it is like one is adding on to the time of the mitzvah similar to sleeping in the sukkah on the eighth day of sukkah with intent to add to sukkot (Rosh Hashana 28b). However, the Shulchan Aruch doesn't quote that it is necessary to have such an intent since the minhag is not to have intent to fulfill the mitzvah of Shema then (like Rashi Eruvin 96a s.v. v'od).</ref>
#If the only ''minyan'' for ''arvit'' is immediately after ''shekiya,'' one should ''daven'' with the ''minyan'' rather than ''davening'' later without a ''minyan''.<ref>Shulchan Aruch 235:1, Mishna Brurah 235:12. Rav Moshe Feinstein in Igrot Moshe OC 2:60 writes that in such a case one should certainly daven with a minyan and either the opinion of Rabbenu Yonah to daven Brachot Kriyat Shema with the congregation or Rav Hai Goan to skip them are acceptable. Biur Halacha 235:1 s.v. v'im quotes the Gra that it is better to wait for the proper time and ''daven'' alone. Igrot Moshe O.C. 2:60 writes that one should only follow this Gra if one always follows the Gra.</ref>

#

===Latest Time===
#One should make sure to ''daven arvit'' before ''chatzot''. If one could either ''daven'' alone before ''chatzot'' or with a ''minyan'' after ''chatzot'' one should rather ''daven'' alone before ''chatzot''.<ref>Ishei Yisrael 28:15 based on Mishna Brurah 235:17 and quoting Rav Chaim Kanievsky, Or Letzion 2:15:9, Piskei Teshuvot 235:10. Piskei Teshuvot (235 fnt. 68) questions this since it is possible to recite kriyat shema before chatzot and then shemona esrei with the minyan after chatzot. [[Dating_Packet| Rav Hershel Schachter (cited in Halachos of Dating)]] holds that one should daven by oneself before chatzot rather than daven with a minyan after chatzot.</ref> Some disagree and allow ''davening'' with a ''minyan'' after ''chatzot,'' as long as one says ''shema'' before ''chatzot''.<ref>Halacha Brurah 235:20</ref>
#After the fact, one may pray [[Arvit|''arvit'']] all night until [[Olot HaShachar|''alot hashachar'']].<ref>Kitzur Shulchan Aruch 70:2</ref>
#One who had a predicament and was not able to ''daven'' at the proper time may recite ''shema'' up until ''netz hachama.''<ref>Shulchan Aruch O.C. 235:4</ref> He may recite ''birchos krias shema'' as well,<ref>Rama O.C. 235:4</ref> yet ''hashkiveinu'' and ''baruch Hashem l'olam'' are not recited after ''alot hashachar.''<ref>Shulchan Aruch O.C. 235:4, Mishna Brurah 235:34</ref> ''Shemoneh esrei'', as well, is not recited after ''alot hashachar.''<ref>Mishna Brurah 235:34</ref>

==Sources==
<references />
[[Category:Prayer]]

Reference of Measurements in Halacha

2024-07-22T13:29:11Z

Schwartz: /* Bein HaShemashot */ I split up the two mil with different titles to help differentiate for links. I left all footnotes intact they are just moved.

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Distance of Mil===

#
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Time period of Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Some consider a ''mil'' to be 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
### Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
### Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
### There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot===

#[[Bein HaShemashot|''Bein hashemashot'']] is the time period between certain daytime and certain nighttime. It is considered a ''safek,'' or doubt, whether it is considered day or night; this has many halachic ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#
#The ''Gemara'' rules that if one does a ''melacha'' on [[Shabbos|''Shabbat'']] for the duration of ''bein hashemashot'' on Friday evening and Saturday evening, one has certainly violated [[Shabbos|''Shabbat'']], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform ''melacha'' during [[Bein Hashemashot|''bein hashemashot'']]. <ref>Mishnah [[Shabbos]] 34b </ref>

=== Tzet HaKochavim (Emergence of the Stars) ===

# There's a major dispute when ''tzet hakochavim'' is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah|''shekiyah'']] and the Gra assumes that it's three quarters of a [[mil|''mil'']] after [[Shekiyah|''shekiyah'']], varying according to one's location.<ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T02:01:35Z

Schwartz: /* Mincha Ketana */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

=== Mincha Ketana ===

# ''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Shekiyah (Sunset)===

#[[Shekiyah|''Shekiyah'']] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Bein HaShemashot===

#[[Bein HaShemashot|''Bein hashemashot'']] is the time period between certain daytime and certain nighttime. It is considered a ''safek,'' or doubt, whether it is considered day or night; this has many halachic ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The ''Gemara'' rules that if one does a ''melacha'' on [[Shabbos|''Shabbat'']] for the duration of ''bein hashemashot'' on Friday evening and Saturday evening, one has certainly violated [[Shabbos|''Shabbat'']], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform ''melacha'' during [[Bein Hashemashot|''bein hashemashot'']]. <ref>Mishnah [[Shabbos]] 34b </ref>

=== Tzet HaKochavim (Emergence of the Stars) ===

# There's a major dispute when ''tzet hakochavim'' is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah|''shekiyah'']] and the Gra assumes that it's three quarters of a [[mil|''mil'']] after [[Shekiyah|''shekiyah'']], varying according to one's location.<ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T01:57:54Z

Schwartz: /* Bein HaShemashot */ This section is not accurate. I'm going to try to work on it.

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the Stars)===

#There's a major dispute when ''tzet hakochavim'' is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah|''shekiyah'']] and the Gra assumes that it's three quarters of a [[mil|''mil'']] after [[Shekiyah|''shekiyah'']], varying according to one's location.<ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot|''Bein hashemashot'']] is the time period between certain daytime and certain nighttime. It is considered a ''safek,'' or doubt, whether it is considered day or night; this has many halachic ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The ''Gemara'' rules that if one does a ''melacha'' on [[Shabbos|''Shabbat'']] for the duration of ''bein hashemashot'' on Friday evening and Saturday evening, one has certainly violated [[Shabbos|''Shabbat'']], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform ''melacha'' during [[Bein Hashemashot|''bein hashemashot'']]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T01:52:12Z

Schwartz: /* Tzet HaKochavim (Emergence of the stars) */ All these links of shkiyah, mil, etc lead to nowhere. Pls advise

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the Stars)===

#There's a major dispute when ''tzet hakochavim'' is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah|''shekiyah'']] and the Gra assumes that it's three quarters of a [[mil|''mil'']] after [[Shekiyah|''shekiyah'']], varying according to one's location.<ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T01:49:00Z

Schwartz: /* Mincha Ketana */ In this section also it can be noted that there is a dispute whether it is from sunrise or from alot

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#''Mincha ketana'' is nine and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T01:39:28Z

Schwartz: /* Plag Hamincha */ This dispute of wether it is 1.25 before shkiya or tzet is the same dispute mentioned earlier on this page #shaot zmaniot. How should we put it here?

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before ''tzet'', the emergence of the stars, and some define it as 1.25 hours before ''shekiya'', sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-22T01:36:38Z

Schwartz: /* Misheyakir */ Moved the minhag Sephardim to the end of the discussion as it is contingent on more than 1 portion of it.

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alot Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===== Minhag Sephardim =====

# According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer; even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#''Mincha gedola'' is six and a half halachic hours (''shaot zmaniot'') after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#''Plag hamincha'' is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-17T14:28:11Z

Schwartz: /* Misheyakir */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===Misheyakir===

#''Misheyakir'' refers to the time in the morning when there is enough light to recognize an acquaintance at a distance of 4 ''amos.'' There is a dispute as to whether this depends solely on the position of the sun, or whether it depends on actual visibility so that other environmental factors (e.g. cloud cover) must be taken into account as well. The accepted ''minhag'' is to base ''misheyakir'' solely on the position of the sun. However, this may be due to the fact that in our times it is not practical to use actual visibility as a barometer. Even at night, acquaintances can be discernable because of all the light pollution.<ref>Dvar Yom Chap. 8:3</ref>
#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree.

*Igrot Moshe EH I:58, OC II:20, OC I:24, OC IV:62 has a different approach to measuring ''chatzot'' and ''shaot zmaniot.'' He writes that ''chatzot'' is at the same time every day and that the morning ''shaot zmaniot'' are of a different length than those of the afternoon. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the times for ''mincha'' see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-17T01:07:56Z

Schwartz: /* Applying these Times */ There are other times given for misheyakir, but I think what you wrote suffices. Should I write in the footnote a few more sources? Maybe a short explanation of what misheyakir is would be helpful.

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Applying these Times ====

# There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===Misheyakir===

#There is a wide range of opinions precisely when ''misheyakir'' occurs in Jerusalem on a perfect day, when there are exactly 12 daylight hours, and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be adapted for other regions and for different times of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that ''misheyakir'' is between 50 and 60 minutes before sunrise in Jerusalem, in New York, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-16T13:58:42Z

Schwartz: /* Degrees */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Applying these Times ====
There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they do not mean to say that the first light appears 72 minutes before sunrise in every locale, on every day of the year. Rather, they are discussing the time of ''alot'' in Israel or Bavel on the equinox at which time the sun is approximately 16.1º below the horizon. By converting ''mil'' into degrees, we are merely conveying the "72 minutes" to apply them to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===Misheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-16T13:49:24Z

Schwartz: /* Degrees */ You may want to add what the Sephardi gedolim say about this. I think these tidbits of information help get a better understanding of what is going on here.

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Applying these Times ====
There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the light from the sun first becomes visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, many ''poskim'' write, that ''alot'' cannot be calculated by time; rather, it must be based on the position of the sun below the horizon. The first light always appears when the sun is a certain number of degrees below the horizon.
# According to this, the measurements given in ''mil'' actually refer to degrees. When the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they are discussing the time of ''alot'' in Israel or Bavel on the equinox; the sun is approximately 16.1º below the horizon at that time. By converting ''mil'' into degrees, these measurements can be adapted to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.''

*Dvar Yom Chap. 7 footnote 58 writes that some people mistakenly think that measuring by degrees is a new invention. How is it possible that 400 years ago they were able to measure the position of the sun below the horizon? He explains that degrees is a way of calculating when the first light will appear. It is easy to understand how they calculated ''alot'' in the olden days - they watched for the first light to appear. </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-16T13:36:43Z

Schwartz: /* Shaot Zmaniot */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Applying these Times ====
There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the first rays of light from the sun become visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, there are many ''poskim'' who write, that ''alot'' cannot be calculated by time; rather, it must be based on the number of degrees that the sun is below the horizon. This is always the time when the first light appears.
# According to this, the measurements given in the amount of ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they are discussing the time of ''alot'' in Israel or Bavel on the equinox; the sun is approximately 16.1º below the horizon at that time. By converting ''mil'' into degrees, these measurements can be adapted to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.'' </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-16T01:01:50Z

Schwartz: /* Shaot Zmaniot */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''Kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Applying these Times ====
There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the first rays of light from the sun become visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, there are many ''poskim'' who write, that ''alot'' cannot be calculated by time; rather, it must be based on the number of degrees that the sun is below the horizon. This is always the time when the first light appears.
# According to this, the measurements given in the amount of ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they are discussing the time of ''alot'' in Israel or Bavel on the equinox; the sun is approximately 16.1º below the horizon at that time. By converting ''mil'' into degrees, these measurements can be adapted to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.'' </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

===== Fixed Minutes =====
#Some hold that ''alot'' is determined by fixed minutes.<ref>Dvar Yom Chapter 7:19-23 raises many questions about the validity of this opinion. This, however, has become a widespread ''minhag'' in America. Kuntres Hatzad Hashaveh (pub.Mifal Talmudo Biyado) was written to uphold the minhag and its sources.</ref> There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-16T00:50:12Z

Schwartz: /* Shaot Zmaniot */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''Kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#Besides making a difference as to when the day starts and ends, this dispute will affect the length of a halachic hour as well. Take for example a day which is 12 hours from ''shkiya'' until ''tzet,'' and let us assume for a moment that there are 72 minutes between both ''alot'' to ''hanetz'' and ''shkiya'' until ''tzet.'' According to the Gra, a halachic hour will be 60 minutes, and according to the Magen Avrohom it will be 72 minutes.
#To illustrate the implication of this dispute let us take ''zman kriat shema'' for example. ''Zman krias shema'' is at the end of the third hour of the day. According to the Gra these hours are measured beginning at ''hanetz'' and are 60 minutes long; the end of ''zman kriat shema'' will be 180 minutes after ''hanetz.'' According to the Magen Avraham the hours are measured from ''alot'' and are 72 minutes long; ''zman kriat shema'' will be 216 minutes after ''alot.'' Subtract 72 from 216 to find that the end of ''zman kriat shema'' according to the Magen Avraham is 144 minutes after ''hanetz -'' this is 36 minutes before the ''zman'' of the Gra.<ref>Dvar Yom (English) Chap. 10:7-9. Dvar Yom writes that calling this ''zman'' the ''zman'' of the Magen Avraham is actually a misnomer. See there for a full discussion.</ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Applying these Times ====
There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the first rays of light from the sun become visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, there are many ''poskim'' who write, that ''alot'' cannot be calculated by time; rather, it must be based on the number of degrees that the sun is below the horizon. This is always the time when the first light appears.
# According to this, the measurements given in the amount of ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they are discussing the time of ''alot'' in Israel or Bavel on the equinox; the sun is approximately 16.1º below the horizon at that time. By converting ''mil'' into degrees, these measurements can be adapted to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.'' </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

'''Fixed Minutes'''

#Some hold that Alot is determined by 4 mil by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-15T20:40:03Z

Schwartz: /* Shaot Zmaniot */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''Kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Applying these Times ====
There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the first rays of light from the sun become visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, there are many ''poskim'' who write, that ''alot'' cannot be calculated by time; rather, it must be based on the number of degrees that the sun is below the horizon. This is always the time when the first light appears.
# According to this, the measurements given in the amount of ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they are discussing the time of ''alot'' in Israel or Bavel on the equinox; the sun is approximately 16.1º below the horizon at that time. By converting ''mil'' into degrees, these measurements can be adapted to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.'' </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that the times given are the actual times for ''alot''; yet they are not measured in terms of a 60 minute hour (''shaot shavot''); rather, in terms of halachic hours (''shaot zmaniot''). For example, on a day that there are 16 hours of daylight, each halachic hour is actually 80 minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref> Taking such a day for example we could calculate the time of ''alot'' in ''shaot zmaniot'' with the following table:
##120 minutes = 160 minutes
##90 minutes = 120 minutes
##72 minutes = 96 minutes

'''Fixed Minutes'''

#Some hold that Alot is determined by 4 mil by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-15T20:29:24Z

Schwartz: /* Degrees */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''Kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Applying these Times ====
There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the first rays of light from the sun become visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, there are many ''poskim'' who write, that ''alot'' cannot be calculated by time; rather, it must be based on the number of degrees that the sun is below the horizon. This is always the time when the first light appears.
# According to this, the measurements given in the amount of ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they are discussing the time of ''alot'' in Israel or Bavel on the equinox; the sun is approximately 16.1º below the horizon at that time. By converting ''mil'' into degrees, these measurements can be adapted to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7, in paragraph 24 he writes that even those who offer other methods for calculating ''alot'', such as ''shaot zmaniot'', agree that when light is visible on the horizon it is ''alot hashachar.'' According to this, one relying on ''shaot zmaniot'' must be stringent using both degrees and ''shaot zmaniot.'' For example, on January 1st in Jerusalem, 16.1 degrees is 5:22, and 72 minutes ''shaot zmaniot'' is 5:38 (see Zemanei Halacha pg.34). If one is fasting and would like to eat before the fast, they would have to stop eating at 5:22 because at that time light is visible on the horizon. However, if one would like to say Hallel one would have to wait until 5:38 which is the halachic time of ''alot'' using ''shaot zmaniot.'' </ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

===== Shaot Zmaniot =====
#Some hold that alot follows the times is determined by degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is 120, 90, and 72 zmaniot minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Fixed Minutes'''

#Some hold that Alot is determined by 4 mil by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-15T20:12:27Z

Schwartz: /* Degrees */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''Kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Applying these Times ====
There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the first rays of light from the sun become visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, there are many ''poskim'' who write, that ''alot'' cannot be calculated by time; rather, it must be based on the number of degrees that the sun is below the horizon. This is always the time when the first light appears.
# According to this, the measurements given in the amount of ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they are discussing the time of ''alot'' in Israel or Bavel on the equinox; the sun is approximately 16.1º below the horizon at that time. By converting ''mil'' into degrees, these measurements can be adapted to any locale and for any time of the year.<ref>Dvar Yom (English) Chap.7</ref>
# The conversion of ''mil'' into degrees is as follows. (This is the number of degrees that the sun is below the horizon in Israel on the equinox at each time.)
##At 120 minutes the sun is 25.9º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 90 minutes the sun is 19.75º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##At 72 minutes the sun is 16.1º below the horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Zmaniot'''

#Some hold that Alot is determined by degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is 120, 90, and 72 zmaniot minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Fixed Minutes'''

#Some hold that Alot is determined by 4 mil by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-15T19:55:04Z

Schwartz: /* Ways to Apply these Times */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''Kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Applying these Times ====
There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the first rays of light from the sun become visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The timing of this varies depending on the locale and the time of year. Thus, there are many ''poskim'' who write, that ''alot'' cannot be calculated by time; rather, it must be based on the number of degrees that the sun is below the horizon. This is always the time when the first light appears.
# According to this, the measurements given in the amount of ''mil'' actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they are discussing the time of ''alot'' in Israel or Bavel on the equinox; the sun is aproximately 16.1º below the horizon at that time. By translating ''mil'' into degrees, these measurements can be adapted to any locale and for any time of the year.

#Some hold that Alot is determined degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes by degrees is 25.9 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##90 minutes by degrees is 19.75 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##72 minutes by degrees is 15.99 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Zmaniot'''

#Some hold that Alot is determined by degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is 120, 90, and 72 zmaniot minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Fixed Minutes'''

#Some hold that Alot is determined by 4 mil by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-15T14:30:56Z

Schwartz: /* Alot HaShachar */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''Kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===

==== Opinions for the time of Alos Hashachar ====
#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

==== Ways to Apply these Times ====
There are three methods in the ''poskim'' as to the practical application of the aforementioned times: degrees, ''shaot zmaniot, shaot shavot.''

===== Degrees =====

# The time of ''alot hashachar'' refers to an astronomical event in which the first rays of light from the sun become visible on the horizon.<ref>Biur Halacha 89:1 quotes ''poskim'' who write that it is when the whole eastern horizon becomes light. This does not make a difference in our discussion.</ref> The sun's rays become visible when the sun is a certain number of degrees below the horizon. The amount of time that this occurs before sunrise varies depending on the locale and the time of year. Thus, there are many ''poskim'' who write that the only way to calculate ''alot'' is based on the number of degrees that the sun is below the horizon. This will consistently be the time when the first light appears. They explain that the measurements given in the ''poskim'' for the amount of ''mil'' before sunrise actually refer to degrees. In other words, when the ''poskim'' write that ''alot'' occurs 72 minutes before sunrise they are discussing the time of ''alot'' in Israel or Bavel on the equinox. The ''poskim'' estimate that the sun is 16.1º below the horizon at that time. Thus, applying this to other times and other locales, it comes out that ''alot hashachar'' is always when the sun is 16.1º below the horizon - this is the time when the first light appears.

#Some hold that Alot is determined degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes by degrees is 25.9 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##90 minutes by degrees is 19.75 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##72 minutes by degrees is 15.99 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Zmaniot'''

#Some hold that Alot is determined by degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is 120, 90, and 72 zmaniot minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Fixed Minutes'''

#Some hold that Alot is determined by 4 mil by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-15T13:53:44Z

Schwartz: /* Alot HaShachar */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''Kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===
'''Halacha'''

#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref><ref>Magen Avrohom 267:1 writes that there are 96 minutes between ''shkiya'' and ''tzet'' (which applies as well to the time period between ''alot'' and ''hanetz.'' This assumes that there are 4 ''mil'' each one being 24 minutes.</ref><ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, ''alot hashachar'' is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

'''Degrees below Horizon'''

#Some hold that Alot is determined degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes by degrees is 25.9 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##90 minutes by degrees is 19.75 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##72 minutes by degrees is 15.99 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Zmaniot'''

#Some hold that Alot is determined by degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is 120, 90, and 72 zmaniot minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Fixed Minutes'''

#Some hold that Alot is determined by 4 mil by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-15T01:04:56Z

Schwartz: /* Alot HaShachar */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''Kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

=== Mil ===

# Some of the daily ''zmanim'' are described in terms of a ''mil.'' This refers to the amount of time it takes for the average person to walk a ''mil'' - 2000 ''amos''. There are three opinions in the ''poskim'' as to how long that takes.
## Shulchan Aruch writes that it takes 18 minutes to walk a ''mil.''<ref>Shulchan Aruch O.C. 459:2</ref>
## Biur Halacha writes that some give an amount of 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref>
## There are others quoted by Biur Halacha who maintain that the amount is 24 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei''</ref><ref>For a further discussion as to how these times were calculated see Dvar Yom (English) Chap. 2.</ref>

===Alot HaShachar===
'''Halacha'''

#There is a debate in the Gemara whether the time from ''alot hasachar'' until sunrise is 4 ''mil'' or 5 ''mil.''<ref>Pesachim 93b -94a. Ulah says that it is 5 ''mil'' while Rav Yehuda says 4 ''mil.''</ref>
#There are different opinions among the ''poskim'' as to the ''psak'' halacha. Coupled with the debate about the timing of a ''mil'', room is made for a few different opinions.
#One view is that it takes 72 minutes from the time of the first light until sunrise. They are assuming that the time of a ''mil'' is 18 minutes, and that it takes 4 ''mil'' from ''alot'' until sunrise.<ref>Rambam Peirush Hamishnayot Brachot 1:1, Abudraham Shaar 1, Hazmanim Bhalacha Chap. 21:7 writes that this is the custom outside Israel.</ref>
#Another opinion is 90 minutes. They conclude as well that there are 4 ''mil'' between ''alot'' and ''hanetz''; yet they set the amount of a ''mil'' at 22.5 minutes.<ref>Biur Halacha 459:2 ''s.v. Havei'' quoting Biur HaGra, Sefer Seder Zmanim. Hazmanim Bhalacha Chap. 21:8 writes that this is the custom in Israel.</ref>
#A third opinion is that the ''mil'' is 24 minutes, and there are 5 ''mil'' between ''alot'' and sunrise. This sets the time of ''alot'' at 120 minutes before ''hanetz.''<ref>Magen Avrohom 459:3, Rav Chaim Noeh coined this as the "custom of Chabad"; yet there were those who disagreed - see Hazmanim Bhalacha Chap.21:9</ref>
#There is yet a fourth opinion that there are 96 minutes between ''alot'' and ''hanetz.'' This is assuming that there are 4 ''mil'' each one being 24 minutes.
#Many ''rishonim'' hold that [[Alot HaShachar|''alot hashachar'']] is 72 minutes before sunrise on a "perfect day" (when sunrise and sunset are exactly 12 hours apart) in Jerusalem which is equivalent to when the sun is 16.1 degrees below the horizon anywhere in the world; however, others hold that [[Alot HaShachar]] is 90 minutes on a perfect day which is 19.78 degrees below the horizon.<ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, Alot HaShachar is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

'''Degrees below Horizon'''

#Some hold that Alot is determined degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes by degrees is 25.9 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##90 minutes by degrees is 19.75 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##72 minutes by degrees is 15.99 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Zmaniot'''

#Some hold that Alot is determined by degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is 120, 90, and 72 zmaniot minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Fixed Minutes'''

#Some hold that Alot is determined by 4 mil by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

Reference of Measurements in Halacha

2024-07-15T00:07:40Z

Schwartz: /* Shaot Zmaniot */

[[Image:Measuring Tools.png|200px|right]]
There are many different [[measurements]] used in the Torah and classical Rabbinic Seforim, which are important for daily living. An example is the specific amount of wine that [[Kiddush]] is made on: One [[Revi'it]]. If one doesn't know how much a [[Revi'it]] is, how can one fulfill the Mitzvah properly?
The modern day equivalents for many Hebrew [[measurements]] are discussed below.
In addition, discussed below are many Halachic times which also matter for everyday use.
==Food or Drink==
===Kezayit===
{| class="wikitable sortable"
!Opinions
!Kezayit (cm3)
|-
|Rav Mordechai Willig<ref>Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters. His calculations are primarily based on Rav Hadar Margolin.</ref>
|22.5
|-
|Rav Chaim Noeh<ref>Rav Chaim Noeh in [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=270 Shiurei Torah (3:11, pg 191, 5707)] writes that for Deoritta Mitzvot one should eat 28.8cc, however, in [https://www.hebrewbooks.org/pdfpager.aspx?req=35168&st=&pgnum=69 Shiurei Tzion (p. 70, 5709)] he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.</ref>
|27
|-
|Rav Moshe Feinstein<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc.</ref>
|31.2
|-
|Chazon Ish<ref>Steipler in Shiurin Shel Torah (second edition, 5750, pp. 65-6; first edition, 5716, pp. 86-7) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg today measures between 45-50 grams. At most, the kezayit would be 33.3 grams. Vezot HaBracha (Birur Halacha 1:3) records this opinion of the Chazon Ish as 33.3cc for a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach who doubles today's eggs to figure out a kebaytzeh ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=118 Chazon Ish OC 39:6]). However, the Chazon Ish also holds that the kezayit is only 1/3 of a kebeytzeh like the Rambam ([https://www.hebrewbooks.org/pdfpager.aspx?req=14336&st=&pgnum=123 Chazon Ish OC 39:17]).</ref>
|33.3
|}

#According to Ashkenazim, all sizes are measured in volume and not weight.<ref>Mishna Brurah 456:3, Vezot HaBracha (pg 6) </ref> However, according to Sephardim the actual halacha is that measures are in volume but the minhag is to follow the measures in weight. <ref>See Yalkut Yosef (Klalei [[Brachot]] pg 195-202) who discusses this at length. However, see Or Letzion (Vol. 3, Introduction) who argues that the custom to use weight is only for foods which have similar density to water, but for other foods (like Matza) one would use volume. Halacha Brurah 210:2 rules that the kezayit is measured by volume and not weight. See Otzrot Yosef 8:9. </ref>
#There’s a dispute in the Rishonim whether the [[Kezayit]] (olive size) is a half or third of a [[KeBaytzah]] (egg size), and regarding [[Bracha Achrona]] and Deoritta Mitzvot, the halacha follows the opinion that a [[Kezayit]] is half a KeBeytzah. <ref>*Mishna Brurah 486:1 writes that the Tosfot holds a [[Kezayit]] is half of a KeBeitzah with the shell and the Rambam holds it is a third of a KeBeitzah (see Tosfot (Yoma 80b s.v. Vshiuro), Rambam (Eiruvin 1:9)). Shulchan Aruch O.C. 486 adopts Tosfot. Rav Avraham Chaim Noeh (Shiurei Torah 3:12) argues that Tosfot holds half a KeBeitzah without the shell.
*What's the halacha? Mishna Brurah 486:1 rules that for Deoritta Mitzvot and [[Bracha Achrona]], one should eat the size of half a KeBeitzah, but for Derabbanan Mitzvot, one third suffices. He adds that since one has to make a Bracha on [[maror]], one should eat half a KeBeitzah.
*Chazon Ish OC 39:17 decided that we could be lenient like the Rambam. See below for an exact amount according to Chazon Ish.
*Background: According to the Ri (Tosfot Yoma 80b) a kezayit is equal to half an egg. He is based on the gemara Yoma 80a that a person can swallow an egg one time and Keritut that a person can swallow two olives at one time. According to the Rambam it is less than a third of an egg. The Rambam holds like Rabbi Yochanan Ben Broka who says that two meals is the volume of 6 eggs (Eruvin 82b) and two meal is also equal to 18 dates (Eruvin 80b). Since the date is bigger than an olive (Yoma 79b) the kezayit is less than a third of an egg. According to rabbenu tam it is less than 30% of an egg. Gra 486 answers the questions for each approach. Rabbenu Tam says we follow Rabbi Shimon who holds that two meals is 5.33 eggs (Eruvin 38b) since according to him the general amount of a loaf is 8 eggs which is broadly accepted in gemara as the primary volume for tumat ochlin which is 1/8 of a loaf. Since two meals is 18 dates (Eruvin 80b) and a date is larger than an olive (Yoma 79b) the olive must be less than 8/27 of an egg. Gra 486 explains each opinion in depth. He answers why the Rambam wasn’t concerned about tumat ochlin since the gemara was discussing an egg without a peel which is 66% the size of a regular egg and the size of an egg for tumat ochlin isn’t precise. That also answers the discrepancy of whether a person can swallow two olives or an egg, the egg discussed is an egg without a peel. He also adds that the Rambam held like Rabbi Yochanan Ben Broka because the Mishna in Peah 8:6 follows his opinion but Tosfot argue that Peah which is biblical isn’t a proof for the size of a meal for eruvin which is rabbinic.</ref>
#According to Rav Chaim Noeh, the [[Kezayit]] for Deoritta measures (eating [[Matzah]]) and [[Bracha Achrona]] is 27cc. The Chazon Ish’s opinion is that the [[Kezayit]] is 33.3 grams (1.3 oz).<ref>*The Tzlach (Pesachim 116b s.v. vhoil) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei Torah Shaar 3) argues that the modern day eggs have not changed from the days of Chazal. Mishna Brurah 486:1 writes that for the mitzvah deoraitta of [[matza]], one should follow the stringent view of the Tzlach. See Rav Shlomo Wahrman (Orot Haesach 28) who explains why there is no need to say that the eggs have shrunk since the times of the Gemara. See also Maaseh Rav 74, where it says that the Gra accepted the position of the Tzlach.
*Practically, how much is a [[Kezayit]]?
**(1) Rav Chaim Noeh in Shiurei Torah (3:11, pg 191, 5707) writes that for Deoritta Mitzvot one should eat 28.8cc, however, in Shiurei Tzion (p. 70, 5709) he writes that it is 27cc. Vezot HaBracha (Birur Halacha 1) explains that Rav Chaim Noeh retracted from his original ruling.
**(2) Steipler in Shiurin Shel Torah (p. 66) quotes the Chazon Ish that a [[Kezayit]] is 2/3 of a modern egg and an egg can possibly be up to 55cc. Therefore, Vezot HaBracha (Birur Halacha 1) writes that the Chazon Ish holds that 33.3cc is a [[Kezayit]]. The Chazon Ish's opinion of [[Kezayit]] is partially based on the opinion of the Tzlach. see also Chazon Ish in Hilchot [[Shabbat]] 39.
**(3) Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Kezayit]] is 31.2cc. [However, Rabbi Bodner in Halachos of K’zayis (p. 24) writes that Rav Dovid Feinstein told him that Rav Moshe never measured the eggs himself and it was his student who calculated 1.1oz, but that if his calculations were more precise he should use those. Therefore, Rabbi Bodner rules, based on his own calculations, that a [[Kezayit]] is 27.2cc.]
**(4) Rav Mordechai Willig ([http://www.yutorah.org/lectures/lecture.cfm/760487/Rabbi_Mordechai_I_Willig/How_Much_Matza_Do_You_Need_to_Eat Pesach To-Go, Nisan 5771], p. 60) is of the opinion that the size in volume of a kezayis is 22.5 cubic centimeters.
**(5) Rav Shlomo Miller (approbation to Hiddurei Hamiddot p. 80, second edition) writes that for a sick person on Pesach they can rely on the kezayit as 4/9 oz or 13.1 cc. It is based on the Ritva Brachot 1:7 and Ri Shu'iv Tzav who write that the reviyit is 2 unkeliyot and he explains that these are equivalent to modern day ounces (see Chavot Yair in Chut Hashani 97 and R' Reich in Mesoret Hashekel) and also uses the opinion that the kezayit is 1/3 of a kebeytzeh.
</ref>
##The minhag of the world and many other authorities is to follow Rav Chaim Noeh’s opinion.<ref>Vezot HaBracha (pg 6, Birur 1, pg 221) quotes Rav Elyashiv and Rav Shlomo Zalman saying that for [[Bracha Achrona]] the widely accepted measurement of the [[Kezayit]] is according to Rav Chaim Noeh. Vezot HaBracha also mentions that such is the minhag of the world. Yachava Daat 1:16 accepts Rav Noeh's opinion.</ref>
#If one ate between a third and a half a [[KeBaytzah]] one should not make a Bracha achrona because of safek [[Brachot]]. Therefore, one should have less than a third and not make a Bracha achrona or more than a half and make a Bracha achrona.<ref>Mishna Brurah 486:1 </ref>
#On Mitzvot Deoritta such as eating [[Matzah]] one must be strict to hold a [[Kezayit]] is a half a [[KeBaytzah]]. However, regarding מצות Derabbanan it’s preferable to hold that a [[Kezayit]] is a half a kebaytzah, however, one may rely on the opinion that a [[Kezayit]] is a third a kebaytzah. <ref>Mishna Brurah 486:1 </ref>
#One needs to make sure that he does not count air in the food as part of the shiur of kezayis. If one has a food that is hollow, a kezayis of that food is considered when the food would be pressed.<ref>Rama 486:1 </ref>
#For more opinions of kezayit see: [https://www.ou.org/torah/files/the-kezayit.pdf OU's article on Kezayit].

===Kedi Achilat Pras===

#See [[Kedi Achilat Pras]] (the time in which a [[Kezayit]] is considered eaten together)

===KeBaytzah===

#According to Rav Chaim Noeh, the KeBaytzah is 55cc, and according to the Chazon Ish, it is 100cc. <ref>Vezot HaBracha pg 6 </ref>

===Revi'it===

#A Reviyit is a [[KeBaytzah]] and a half.<ref>Mishna Brurah 486:1 </ref> Therefore, Rav Chaim Noeh holds that the [[Reviyit]] is 86 grams (3 oz),<ref>[https://www.hebrewbooks.org/pdfpager.aspx?req=35168&pgnum=68 Shiurei Tzion (p. 69 n. 6)], [https://www.hebrewbooks.org/pdfpager.aspx?req=20888&st=&pgnum=253 Shiurei Torah (p. 176 3:6)]</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref>Steipler in Shiurin Shel Torah (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the Revi'it is 3.3 oz.<ref>Vezot HaBracha (Birur Halacha 1) quotes Haggadat Kol Dodi which quotes Rav Moshe Feinstein as saying that a [[Reviyit]] is 3.3 oz.</ref>
#With regards to drinking [[the four cups of wine]], see the [[Required Amount of Matzah and Wine for the Seder]] page.

===Kedei Shtiyat Reviyit===

#See [[Bracha_Achrona#Drink |Kedei Shtiyat Revi'it]] (the time in which a Revi'it is considered drunk together).

===Ayfah, Seah, Kav, Log===
{| class="wikitable sortable"
!Shiur<ref>Rashbam Pesachim 108b s.v. dhaynu explains that an ayfeh is three seah, which is six kav, which is four log, which is six kebeytzot. Shulchan Aruch OC 486:1 rules like Tosfot that a Kebeytzah is two kezaytim. For shiur of kezayit see [[#Kezayit]] above.</ref>
!Ayfah
!Seah
!Kav
!Log
!Kebeytzah
!Kezayit
!cm3
!inch3
|-
|Ayfah
|1
|3
|18
|72
|432
|864
|23328
|1424
|-
|Seah
|1/3
|1
|6
|24
|144
|288
|7776
|475
|-
|Kav
|1/18
|1/6
|1
|4
|24
|48
|1296
|79
|-
|Log
|1/72
|1/24
|1/4
|1
|6
|12
|324
|20
|-
|Kebeytzah
|1/432
|1/144
|1/24
|1/6
|1
|2
|54
|3.3
|-
|Kezayit
|1/864
|1/288
|1/48
|1/12
|1/2
|1
|27
|1.6
|}

#For example the average apple's volume is 104.5 cm3 which is 3.9 kezaytim.<ref>https://cigrjournal.org/index.php/ejounral/article/view/1124</ref>

==Length==
===Amah, Tefach, Etzbah===
{| class="wikitable sortable"
!
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136. writes that the [[Amah]] is 21.25 inches and one can be strict to hold that it is 23 inches. Similarly, the Aruch Hashulchan YD 286:21 writes that 4 amot is one Russian ''sazhen'' which is the equivalent of 7 feet (see [https://en.wikipedia.org/wiki/Obsolete_Russian_units_of_measurement Wikipedia's page on Russian measurements]) meaning that the amah is 21 inches. [https://asif.co.il/download/kitvey-et/kol/kol-30/1-29.pdf Dr. Gideon Freedman in Kol Bramah v. 4 p. 229] proves that the Aruch Hashulchan YD 201:3 and Mishna Brurah 358:7 both hold that the amah is 21 inches. The Aruch Hashulchan says that an amah is three quarters of an arshin and an arshin is 71.12 cm. The Mishna Brurah ties 53 Russian arshins to 70.83 amot. See there for the calculations.</ref>
|21.25 in. (53.98 cm)
|3.54 in. (9.00 cm)
|0.89 in. (2.25 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Torah (p. 71 n. 21) </ref>
|18.90 in. (48 cm)
|3.15 in. (8 cm)
|0.79 in. (2 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (5750 p. 63) by the Steipler quotes the Chazon Ish as holding that the measure of the tefach is 9.62cm and when measuring with larger measures would be a stringency one should use 9.8cm. For some of the measurements there the tefach is rounded up to 10cm. Also, on p. 3 the measurements are converted to inches and it approximates the tefach as 4 inches. However, he references p. 63 for the more accurate measurements. Also, he notes that these are approximate measures, which he did because of the need to publicize the measures but not an accurate calculation.</ref>
|22.72 in. (57.72 cm)
|3.79 in. (9.62 cm)
|0.95 in. (2.41 cm)
|}

When measuring an amount that would be a stringency to use a larger measure, the poskim have slightly larger measures. They are 1/48 larger than the above measures.<ref>Rava in Eruvin 3b states that when measuring with a larger measure would be a stringency one should use a larger tefach, in which the etzba'ot are spaced out. However, if using a larger measure would yield a leniency the smaller measure of a tefach, with the etzba'ot measured without any space, should be used. Rashba (cited by Chidushei Hameiri Eruvin 3a, Maggid Mishna, and Beit Yosef YD 201) explains that the larger measure is 1/48 larger than the smaller measure. Rav Chaim Noeh in Shiurei Torah p. 249 and Shiurei Tzion p. 71 spells this out how the halacha follows the Rashba and does the calculation for his measurements. Steipler (Shiurin Shel Torah p. 63) does the same for his measurements also using the Rashba's conversion factor.</ref>
{| class="wikitable sortable"
!Larger Measures
!Amah
!Tefach
!Etzbah
|-
|Rav Moshe Feinstein<ref>Sh”t Igrot Moshe O”C 1:136</ref>
|21.69 in. (55.10 cm)
|3.62 in. (9.18 cm)
|0.90 in. (2.30 cm)
|-
|Rav Chaim Noeh<ref>Shiurei Torah (Siman 3 Seif 25 pg 249), Shiurei Tzion (p. 71 n. 21) </ref>
|19.29 in. (49 cm)
|3.22 in. (8.17 cm)
|0.80 in. (2.04 cm)
|-
|Chazon Ish<ref>Shiurin Shel Torah (p. 63). </ref>
|23.20 in. (58.92 cm)
|3.87 in. (9.82 cm)
|0.97 in. (2.46 cm)
|}

===Mil===

#When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes.<ref>Shulchan Aruch O.C. 459:2 writes that the [[mil]] is 18 minutes. Rama 261:1 agrees. Beiur Halacha 459:2 s.v. Haviy quotes some who consider it 22.5 minutes and others who say that it is 24 minutes.

*The 18 minute mil emerges from calculating that it is possible to travel 40 mil over 12 hours from netz until shekiya. On an equinox day, there are 720 minutes from sunrise until sunset, yielding a 18 minute mil (720/40=18). This is the opinion of the Rambam Pirush Mishnayot Brachot 1:1, Trumat Hadeshen, and Shulchan Aruch O.C. 459:1.
*The 22.5 minute mil is based on the understanding that a person could walk 40 mil from olot to tzet, with 4 mil from olot until netz and 4 mil from shekiya until tzet, leaving 32 mil from netz until shekiya. Dividing up the 12 hours of the equinox day into 32 equal sections produces a 22.5 minute mil (40-4-4=32; 720/32=22.5). This is the opinion of the Gra 459:1 and Zmanim Khalacha pp. 19-20.
*The 24 minute mil is sourced in the Rambam Korban Pesach 5:8 and Pirush Mishnayot Pesachim 9:1 who holds that a person could travel 15 mil from netz until chatzot and when doubled it emerges a person can travel 30 mil from netz until shekiya. Diving 12 hours into 30 equal parts yields a 24 minute mil (720/30=24).</ref>
#When [[Mil]] is given in terms of distance it is equal to 2000 [[Amot]].<ref>Rashi Yoma 67a s.v. shivah and Tosfot Shabbat 34b s.v. safek write that a mil is 2000 amot. Shulchan Aruch O.C. 261:2 writes that 3/4 of a [[mil]] is equal to 1500 [[amot]], implying a [[mil]] is 2000 [[amot]]. [http://www.yeshiva.org.il/midrash/shiur.asp?id=15883#3b Rabbi Melamed on yeshiva.org.il] writes that a [[mil]] is 2000 [[amot]].</ref>

==Money==
{| class="wikitable sortable" style="text-align:right; vertical-align:bottom;"
|- style="text-align:left;"
!Coin<ref>Gemara Kiddushin 12a</ref>
!Sela
!Dinar
!Maah
!Pundiyon
!Isur
!Prutah
|-
| style="text-align:left;" |Sela
|1
|4
|24
|48
|96
|768
|-
| style="text-align:left;" |Dinar
|1/4
|1
|6
|12
|24
|192
|-
| style="text-align:left;" |Maah
|1/24
|1/6
|1
|2
|4
|32
|-
| style="text-align:left;" |Pundiyon
|1/48
|1/12
|1/2
|1
|2
|16
|-
| style="text-align:left;" |Isur
|1/96
|1/24
|1/4
|1/2
|1
|8
|-
| style="text-align:left;" |Prutah
|1/768
|1/192
|1/32
|1/16
|1/8
|1
|}
===Prutah===

#A [[prutah]] is 1/40 of a gram of silver, which today is equal to {{PrutaVar}} cents.<ref>This evaluation of the pruta in pennies uses the price of an ounce of silver given by a webserver with that information [http://services.packetizer.com/spotprices/ here].</ref> However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]].<ref>Shulchan C.M. 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei Torah (Rav Chaim Noeh pg 177) and Shiurin Shel Torah (Steipler p. 65; first edition p. 86) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). Rav Hadar Margoliyat in Hiddurei Hamiddot (second edition p. 252) concludes that the prutah is no more than 1/45 of a gram. Halachos of [[Chanukah]] (Rabbi Shimon Eider, pg 38) quotes Rav Moshe Feinstein saying that a [[prutah]] is 2 or 3 cents and not just one penny. See Halachos of Other People’s Money (Rabbi Bodner pg 150) who quotes Rav Moshe regarding a [[prutah]] for the mitzvah of returning a lost object. </ref>

===Dinar===

#A dinar is 192 pruta's or 4.8 grams of silver.<ref>Rashi Kiddushin 12a s.v. aliba</ref>

===Asara Zehuvim===

#If someone steals someone else's mitzvah they should pay them the 10 zehuvim, which is equal to 1200 grams of silver (roughly $650 but varies).<ref>Rav Chaim Noeh (Shiurei Torah p. 379 ch. 3 n. 45) writes that the 10 zehuvim are equal to 250 silver dinar which are 1200 grams of silver.</ref>

==Time==
Generally, one can search for zmanim on [http://www.myzmanim.com| myzmanim.com] and for a time according to degrees below horizon anywhere in the world on [https://www.suncalc.org/| suncalc.org].
===Shaot Zmaniot===

#[[Shaot Zmaniot|''Shaot zmaniot'']] are halachic hours which are calculated by dividing the daytime hours into 12.<ref>Rambam Peirush Hamishnayot Brachot 1:2 writes that all ''shaot'' in the Mishna are ''shaot zmaniyot.'' Rama 233:1 agrees. Gra on Shulchan Aruch O.C. 443 quotes this Rambam and supports his view from many sources.</ref>
#Chazon Ish explains the reason that halachic hours are divided based on the daylight hours and are not 60-minute hours. ''Chazal'' did not establish halachic hours as an entity of themselves; rather, they were designed as a description of when mitzvot may be done. For example: ''Kriat shema'' must be said before a quarter of the day has passed; ''chazal'' divided the day into hours to illustrate that time. Since the time for mitzvot is based on the length of daylight, the clearest way to depict this is with ''shaot zmaniyot.'' It was ''chazal's'' decision whether to make these 12 hours of daylight run from ''alot'' to ''tzet'', or from ''hanetz'' to ''shkiya.'' What their conclusion was is the subject of great debate.<ref>Chazon Ish O.C. 13 Article 1</ref>
#There’s a dispute of how to measure the day; some count the day from ''alot hashachar'' until [[Tzet HaKochavim|''tzet hakochavim'']] (Magen Avraham) <ref>Many authorities holds that the halachic hours in the day are considered from Olot including: Sh”t Trumat HaDeshen 1, Levush 267, Minchat Cohen (Mevoh Shemesh 2:6) in name of Tosfot Ramban and Rashba, Bach (431), Taz 433, Pri [[Chadash]] 443, Magen Avraham 58:1, 433:3, Eliyah Raba 58:2, Mizbe’ach Adama 4a, Mikraeh Kodesh 158b, Mateh Yehuda 433, Sh”t Chaim Shal 2:38(70), Tov Ayin 18:38, Sh”t Teshuva MaAhava 1:25, Shalmei Tzibbur 93c, Chesed Alafim 58:5, Chaye Adam 21:3,27:1, Kitzur Shulchan Aruch 17:1, Magen Giborim (Shiltei Hagiborim 58:3), and Rav Poalim O”C 2:2. </ref>, and some count it from [[HaNetz|''hanetz'']] until [[Shekiah|''shekiah'']] (Gra).<ref>Many authorities hold that the halachic hours of the day are considered to begin from [[HaNetz]] incluing: Rambam’s Sh”t Pear Hadar 44 (as understood by Halacha Brurah (Shaar Tzion 58:17), Rav Chaim Drok (Noam 9 pg 235), and Orot Chaim 320 against the Yetsiat Mitzmayim (Sefaka Deyoa pg 115)), Siddur Rav Sadyah Goan pg 12, Minchat Cohen Mevoh Hashemesh 2:6 in name of Goanim, Rambam, Rabbenu Yonah, Hagahot Maimon, and Mordechai (Pri [[Chadash]] rejects his proofs), Shiltei Hagiborim on the Mordechai ([[Brachot]] 4:3) (as understood by Magen Avraham 233:3, Shaar Tzion 233:10, and Kaf HaChaim 233:7), Levush (233:1,267), Shaarei Knesset Hagedolah 58:8, Tosfot [[Yom Tov]] (Pesachim 2:3), and Biur HaGra 459:2.</ref>
##According to Sephardim, regarding Biblical laws (including [[Kriyat Shema|''kriyat shema'']]) one should be strict for the opinion of the Magen Avraham. <ref>In conclusion, Minchat Cohen (Mevoh Hashemesh 2:9), Erech HaShulchan 433, Halichot Olam (vol 1, Vaera 3), and Yalkut Yosef (vol 1, pg 98) write that one should be strict for the opinion of the Magen Avraham for Deoritta issues, for example [[Kriyat Shema]]. </ref>
##Among Ashkenazim, some are strict to hold like the Magen Avraham, unless there is a serious need, in which case one may hold like the Gra. <ref>Rabbi Yechiel Michel Tukachinsky in Sefer Eretz Yisrael (pg 18#3) writes that the minhag of [[Israel]] is to follow the magen avraham and only under pressure may one rely on the Gra.</ref> However, some are lenient to rely on the Gra. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 77-79) says that many follow the opinion of the Gra in calculating the time for Sof [[Kriyat Shema]]. </ref>
#There are ''rishonim'' and ''poskim'' who maintain that most ''shaot'' are ''shaot shavot'' - of equal time - 60-minute hours.<ref>Terumas HaDeshen 121</ref> However, this is not the accepted halacha. One reason given for this opinion is that many halachic times are based on peoples' daily schedule. Daily schedules do not vary based on the amount of daylight hours. For example: the end time for ''kriat shema'' is set based on the time that princes arise each day. Princes arise the same time each day, regardless of whether the sun rises at 5:30 or at 7:30.<ref>For further discussion see Ha'zmanim B'halacha Chap.12 n.11-17</ref>

===Alot HaShachar===
'''Halacha'''

#Many ''rishonim'' hold that [[Alot HaShachar|''alot hashachar'']] is 72 minutes before sunrise on a "perfect day" (when sunrise and sunset are exactly 12 hours apart) in Jerusalem which is equivalent to when the sun is 16.1 degrees below the horizon anywhere in the world; however, others hold that [[Alot HaShachar]] is 90 minutes on a perfect day which is 19.78 degrees below the horizon.<ref>*The Rosh (Brachot 4:1) writes that Alot for the korban tamid and Shacharit is after the rays of the sun begin to show and also the Eastern part of the sky began to become light. This is also the opinion of the Rabbenu Yerucham cited by Bet Yosef 89:1. Shulchan Aruch 89:1 codifies their opinion. Magen Avraham 89:3 argues that many rishonim hold that Alot is once the rays of the sun begin to show even though the Eastern part of the sky isn't light. Torat Yoma 28a siman 11 writes that the Rambam Pirush Mishnayot Yoma 3:1 and Ritva Yoma 28a hold like the Rosh and Rabbenu Yerucham, while Rashi sides with the Magen Avraham. Practically, the Mishna Brurah (Biur Halacha 89:1 s.v. v'im) writes that one shouldn't be lenient for the Magen Avraham as the Eliya Rabba, Mateh Yehuda, and Gra argue with the Magen Avraham. Therefore, Alot is once the rays of the sun began to show and also the Eastern part of the sky became light.
*Sefer Zmanim KeHilchatam (Rabbi Berstein, pg 347) writes that 72 minutes on a perfect day in Jerusalem is equal to when the sun is 16 degrees below the horizon and 90 minutes is equal to 19.78 degrees below the horizon. He personally rules that one should be strict for both of these opinions for Deoritta halachas and those derabbanan halachas where safek is lechumra. He tries to prove that this is the opinion of the Mishna Brurah (92:3, Beiur Halacha 163:1 s.v. Berachok). However, he totally rejects the opinion that [[Alot HaShachar]] is 120 minutes before sunrise. [It is noteworthy that astronomical dawn is the time when the Sun is at 18 degrees below the horizon and before then the sky is absolutely dark ([timeanddate.com https://www.timeanddate.com/astronomy/different-types-twilight.html]).]
*He also quotes Rabbi Tukachinsky who held like the opinion of 90 minutes.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 65-7) says that we assume that [[Alot HaShachar]] depends on degrees below horizon and the specific times vary according to one’s location. Similarly, [http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 19-21) mentioned in passing that [[Alot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude.</ref>
#According to Sephardim, Alot HaShachar is 72 seasonal minutes before sunrise.<ref>Yalkut Yosef, Kitzur Shulchan Aruch, Siman 58, Seif 3. </ref> These minutes are proportional to the length of the day,<ref>Yalkut Yosef, Pesuke DeZimra and Keriat Shema, pages 432-433 based on Rambam, Perush Mishnayot, Masechet Berachot, Perek 1.</ref> and do not depend on current location.<ref>Zmanim KHalacha, page 43, quoting Hacham Ovadia zt"l. Hence, 72 minutes would be 1.2 multiplied by the day's shaa zmanit. Rabbi Yehuda Levi, author of Zmanim KHalacha, argues with Hacham Ovadia on the same page. He writes that the 72 minutes are not calculated based on the shaot zmaniot and do depend on current location. Rabbi Levi's difficulties stem from the Rambam's language and astronomic calculation. In the Berachot (1:1), Rambam uses a unique Arabic term when referring to alot hashachar, one that is not used in reference to zman Kriyat Shema (Berachot 1:5) or a the time of a mil (Pesachim 3:2). Furthermore, in the winter, it starts to become light earlier than it starts to become light the spring and the fall, despite having shorter shaot zmaniot in the winter; given this reality, it is difficult to justify calculating alot hashachar strictly according to shaot zmaniot. Therefore, Rabbi Levi maintains that alot hashachar's calculation is determined by degrees below the horizon.</ref>

'''Degrees below Horizon'''

#Some hold that Alot is determined degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes by degrees is 25.9 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##90 minutes by degrees is 19.75 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>
##72 minutes by degrees is 15.99 degrees below horizon.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Zmaniot'''

#Some hold that Alot is determined by degrees below horizon. There are three opinions about the measure of the mil and therefore, there are three opinions of when Alot is 120, 90, and 72 zmaniot minutes.<ref>Zmanei Hahalacha Lmaaseh p. 18</ref>

'''Fixed Minutes'''

#Some hold that Alot is determined by 4 mil by fixed minutes. There are three opinions as to the measure of the mil and therefore, there are three opinions of when Alot is:
##120 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 120 minutes fixed is based on the rishonim that a mil is 24 minutes and there is 5 mil between Alot and Netz.</ref>
##90 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 90 minutes fixed is based on the rishonim that a mil is 22.5 minutes and there is 4 mil between Alot and Netz. He writes that Rav Tukachinsky used that for his luach, though he argues that we shouldn't follow it since Shulchan Aruch held of the 18 minute mil.</ref>
##72 minutes fixed before Netz.<ref>Zmanei Hahalacha Lmaaseh p. 18 writes that 72 minutes fixed is based on the rishonim that a mil is 18 minutes and there is 4 mil between Alot and Netz.</ref>

===MeSheyakir===

#There is a wide range of opinions precisely when Misheyakir occurs in Jerusalem on a perfect day, when there is exactly 12 daylight hours and every seasonal hour consists of 60 minutes. The three opinions include: 35 minutes before sunrise,<ref>Rav Moshe Feinstein in Le-Torah ve-Hora'ah Vol. 3:7 and in Iggeros Moshe OC 4:6 holds of 35 minutes. Rav Yaakov Kamenetsky in Emes liyaakov OC 58:1 rules that it is 36 minutes before sunrise. Zmanei Halacha LeMaaseh (pg 19) holds of 40 minutes before sunrise. </ref> 60 minutes before sunrise,<ref>Rav Tukaczinsky in Sefer Eretz Yisrael 1:4 (pg 18), Kaf HaChaim 18:18, Sh"t Binyan Tzion 2:16 hold of 60 minutes before sunrise. Nivreshet (vol 1, pg 43) holds of 52 minutes.</ref> and 66 minutes before sunrise.<ref>Rav Ovadya Yoseh in Yechave Daat 2:8</ref>
#The various opinions would then have to be extrapolated according to the region of the world and time of year.<ref>*There are two factors at work here: First, the processes of daybreak and nightfall occur faster at places near the equator than places further away from the equator. Second, the speed of these processes are also affected by the seasons.
*A common solution would be to use seasonal minutes. In order to calculate a seasonal hour, one would need to add up all the daytime minutes and then divide by 12 to get the number of minutes that are in each seasonal hour. For instance, if there were 11 hours of daylight, each seasonal hour would consist of 55 minutes. To further complicate matters, there are two ways of counting the daytime minutes: The Magen Avraham counts from dawn until nightfall with the emergence of 3 stars, whereas the Gra counts from sunrise to sunset.
*Another means for calculation, which has only recently been implemented, is to compare the level of brightness by using the relative position of the sun. For instance, it has been determined that 60 minutes before sunrise on a perfect day in Jerusalem the sun is 12.9 degrees below the horizon. Therefore, if one wanted to find the equivalent time anywhere in the world during any season, he would simply determine at what time the sun will be 12.9 degrees below the horizon in that locale on that day and that would be the extrapolated Meshiyakir.</ref> Thus, according to the commonly accepted opinion that Meshiyakir is between 50 and 60 minutes before sunrise in Jerusalem - In New York, depending on the time of the year, it could be anywhere from 56-73 minutes before sunrise.<ref>MyZmanim.com. These figures are determined using MyZmanim’s earliest published position of 11.5 degrees below the horizon. Unfortunately, MyZmanim.com only offers calculations based upon 10.2 degrees, 11 degrees, and 11.5 degrees but not 12.9 degrees. It is unfortunate because 12.9 degrees correlates to Rav Tukaczinsky’s 60 minutes before sunrise which, although is a very lenient position is also well collaborated and accepted.

*[http://www.ou.org/webcast_kosher Rav Yisrael Belsky] (OU Kosher Webcast, 2011, min 21-23) mentions in passing that [[MeSheYakir]] is about 40 or 50 minutes before sunrise.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 68-70) says that Rav Moshe held [[MeSheYakir]] is between 35-40 minutes before sunrise and seems to agree with him, although he mentions that some say it’s 55 minutes before sunrise.</ref>

===HaNetz HaChama (Sunrise)===

#[[HaNetz HaChama]] is sunrise which is halachically the same as the astronomical calculation of sunrise.<ref>*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunrise is the same as the sunrise calculated by the naval observatory which is when the sun begins to rise. Halacha Brurah 58:7 proves that netz is astronomical sunrise when the upper edge of the sun is on the horizon as opposed to the opinion of the Divrei Dovid 36 and Ben Ish Chai Vayishlach no. 4 that it is 2.6 minutes earlier.
*[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 72-77) says that sunset should be determined as though the mountains to the east and west are at sea level and do not block the visibility of the sun. However, the elevation of the place one is currently located is taken into consideration and if one is in a valley the sunset is a little later (less than 5 minutes) than what would have been visible. Yet, he adds, that most opinions hold that regarding sunrise both one’s location’s elevation and surrounding mountains are taken into consideration.</ref> This is the standard time printed for netz such as on myzmanim.com.

===Chatzot===

#[[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Shulchan Aruch Harav 1:8 and Birkei Yosef 1:5 write that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world. Mishna Brurah 1:9 and Chazon Ovadia (Yamim Noraim pg. 3) agree. </ref> This is calculated as halfway between sunrise and sunset, meaning 6 halachic hours after sunrise, see [https://www.myzmanim.com/search.aspx myzmanim.com]<ref>Chazon Ovadia Yamim Noraim pg. 3. [https://din.org.il/2016/01/09/%D7%95%D7%99%D7%94%D7%99-%D7%91%D7%97%D7%A6%D7%99-%D7%94%D7%9C%D7%99%D7%9C%D7%94-%D7%96%D7%9E%D7%A0%D7%99-%D7%97%D7%A6%D7%95%D7%AA-%D7%94%D7%99%D7%95%D7%9D-%D7%95%D7%97%D7%A6%D7%95%D7%AA-%D7%94/ see din.org] for at length discussion. 
see however Minchat Shlomo 1:91:15 regarding the latest time to eat Afikoman on Pesach </ref>

===Mincha Gedola===
Regarding all of the laws of reciting mincha at that time or later see the [[mincha]] page.

#Mincha Gedola is six and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>

===Plag Hamincha===

#Plag Hamincha is 10.45 hours into the day.<ref>Gemara Brachot 26b, Shulchan Aruch O.C. 233:1</ref> Some define it as 1.25 hours before Tzet, the emergence of the stars, and some define it as 1.25 hours before Shekiya, sunset.<ref>See Magen Avraham 267:1 and [[When_Is_the_Earliest_and_Latest_Time_to_Pray%3F#Maariv_Before_Sunset_If_One_Davened_Mincha_Early]]. Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12), Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. However, Kaf Hachaim 233:7 and Halichot Olam v. 1 p. 248-9 hold that plag can be calculated 1.25 hours before shekiya like the Gra.</ref>

===Mincha Ketana===

#Mincha Ketana is nine and a half halachic hours (Shaot Zmaniot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>

===Shekiyah (Sunset)===

#[[Shekiyah]] is sunset which, in general, is halachically the same as the astronomical calculation of sunset. <ref>[http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha Rav Hershel Schachter on yutorah.org] (min 69-72) says that sunset is the same as the sunset calculated by the naval observatory which is when the sun has completely set. </ref>

===Tzet HaKochavim (Emergence of the stars)===

#There's a major dispute when Tzet HaKochavim is: Rabbenu Tam assumes that it's about 72 minutes after [[Shekiyah]] and the Gra assumes that it's three quarters of a [[mil]] after [[Shekiyah]], varying according to one's location. <ref>Rabbi Hershel Schachter on [http://www.yutorah.org/lectures/lecture.cfm/728553/Rabbi_Hershel_Schachter/Shiur_on_Zmanim_in_Halacha# yutorah.org (min 43-5)] explains that many practice like the Gra regarding Tzet HaKochavim on [[Motzei Shabbat]]. See Biur HaGra and Mishna Brurah 261. Pri Megadim assumes that according to Rabbenu Tam, 72 minutes is a fixed time, but Mishna Brurah writes that it varies according to one's location.</ref>

===Bein HaShemashot===

#[[Bein HaShemashot]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a ''safek,'' or doubt, whether it is considered day or night and has many practical ramifications. There is a major dispute regarding the length of this period. <ref>*'''(1) Gemara [[Shabbat]]''' 34b says [[Bein HaShemashot]] is considered as a doubt whether it is considered daytime or nighttime. When is [[Bein HaShemashot]]? Rabbi Yehuda says that [[Bein HaShemashot]] starts from [[Shekiyah]] and concludes when the entire ball of the sun has set. Rabbi Yose, however, says that [[Bein HaShemashot]] is as short as the blink of an eye, though R. Yose also agrees that there is a doubt (Tosfot 34b s.v. Rabbi Yose). R. Nechemya says that it is from [[Shekiyah]] and lasts the length of time it takes to walk a half [[mil]]. [Note, a mil is 2000 amot (see above).]
*'''Explanation of Rabbi Yehuda's opinion:''' Rabba explains Rabbi Yehuda as saying that [[Bein HaShemashot]] starts from [[Shekiyah]] even though the sky is still red, while Rav Yosef says [[Bein HaShemashot]] starts from when the sun already set. It follows, says the Gemara, that according to Rabba the span of [[Bein HaShemashot]] is 3/4 of a [[mil]] and according to Rav Yosef [[Bein HaShemashot]] is 2/3 of a [[mil]].
*'''Who do we follow, Rabba or Rav Yosef, in explaining Rabbi Yehuda?''' The Rif (15a) writes that since it is unclear whether halacha follows Rav Yosef or Rabba, one should be strict to follow Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Then he says that it seems halacha should follow Rabba because halacha always follows Rabba with three exceptions and this isn't one of them. Similarly, Rambam ([[Shabbat]] 5:4) rules like Rabba that [[Bein HaShemashot]] begins at [[Shekiyah]]. Rabbenu Yonah (quoted by Rosh [[Shabbat]] 2:23) argues that since they're not arguing about which logic is correct but about what Rav Yehuda said the halacha follows both Rabba and Rav Yosef, whichever way will be a stringency. Therefore, in context of [[accepting Shabbat]], Rama 261:1 rules like Rabba that [[Bein HaShemashot]] is 3/4 of a [[mil]].
*'''Explanation of Rabbi Yose's opinion:''' Shmuel ([[Shabbat]] 35a) says that Rav Yose’s concept of [[Bein HaShemashot]] takes place after the [[Bein HaShemashot]] already finished. Tosfot ([[Shabbat]] 34b s.v. Rabbi Yose) explains that even according to Rabbi Yose there’s a window of time when there is an uncertainty whether it is day or night but it isn’t as long as it is for Rabbi Yehuda. Rosh (Shabbat 2:23) discusses whether Rabbi Yose's [[Bein HaShemashot]] begins immediately after Rabbi Yehuda's or a while afterwards and doesn't come to a clear conclusion. Rashi to 35a s.v. Bein HaShemashot DeRabbi Yose seems to hold that it is right after R. Yehuda's period.
*'''Who does the halacha follow? Rabbi Yehuda or Rabbi Yose''' The Briatta ([[Shabbat]] 34b) says that in regards to practical ramifications [[Bein HaShemashot]] is always considered day as a stringency and night as a stringency. Rif ([[Shabbat]] 14b) and Rambam ([[Shabbat]] 5:4) codify this Briatta. Shulchan Aruch 261:1 rules that during [[Bein HaShemashot]] one may not do anything one may not do on [[Shabbat]] with some exceptions (see there). Therefore, Rabbi Yochanan ([[Shabbat]] 35a) says that we follow Rabbi Yehuda regarding [[Shabbat]] as a stringency and Rabbi Yose regarding Trumah as a stringency. Rif (15a) and Rosh 2:23 codify Rabbi Yochanan as halacha.
*'''(2) Gemara Pesachim''' 94a records Rabbi Yochanan's statement that an average person can walk 30 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and 5 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]] (according to Rashi s.v. Ovav). The Gemara challenges this and explains really an average person can walk 32 [[mil]] from [[HaNetz HaChama]] until [[Shekiyah]] and only 4 [[mil]] from [[Shekiyah]] until [[Tzet HaKochavim]].
*'''The opinion of Rabbenu Tam:''' Tosfot (Pesachim 94a s.v. Rabbi Yehuda and [[Shabbat]] 35a s.v. Trei) is bothered how the Gemara [[Shabbat]] seems to say that from [[Shekiyah]] until [[Tzet HaKochavim]] a person can walk 3/4 of a [[mil]] (according to the Rabba) and the Gemara Pesachim says a person can walk 4 [[mil]]. Rabbenu Tam answers that the Gemara [[Shabbat]] was referring to the end of the [[Shekiyah]] and from then until [[Tzet HaKochavim]] is 3/4 of a [[mil]], while the Gemara Pesachim is discussing the beginning of [[Shekiyah]] which takes 4 [[mil]] until [[Tzet HaKochavim]]. Ramban (cited by [[Maggid]] Mishna), [[Maggid]] Mishna ([[Shabbat]] 5:4), and Ran ([[Shabbat]] 15a) agree. The Ran ([[Shabbat]] 15a) explains that according to Rabbenu Tam there's two Shekiyot. After the first it is still considered daytime until 3.25 [[mil]] after the beginning of the [[Shekiyah]]. [[Bein HaShemashot]], which is uncertain day or night, spans 3/4 of a [[mil]] and begins from the beginning of the second [[Shekiyah]]. See Beiur Halacha 261 s.v. Metechila who explains that the first [[Shekiyah]] is when the sun sets from our vision, and the second [[Shekiyah]] is when the light from the sun leaves the sky.
*'''Does halacha follow Rabbenu Tam?''' The Shulchan Aruch 261:2 rules in accordance with Rabbenu Tam and states that from the beginning of the [[Shekiyah]] until [[Bein HaShemashot]] there's 3.25 [[mil]] and then [[Bein HaShemashot]] itself is .75 of a [[mil]], which is equivalent to the time it takes to walk 1500 [[amot]]. Beiur Halacha 261 s.v. Metechila writes that for sure one should be strict for the Gra not to do any melacha after sunset.
*'''(3) Shmuel's opinion:''' Then, Shmuel ([[Shabbat]] 35b) says that [[Bein HaShemashot]] is as long as two stars are seen in the sky, but if there’s only one star, it’s day, and if it’s three, then it’s night. The Gemara then clarifies that the stars which were discussed are medium size stars. Similarly, the Yerushalmi ([[Brachot]], cited by Ran 15a) says that [[Shabbat]] concludes when three stars can be seen in one area and not spread out. The Rambam ([[Shabbat]] 5:4) rules like Shmuel that when three medium size stars are seen it is certain nighttime. The Kesef Mishna ([[Shabbat]] 5:4) is bothered why the Rambam said that [[Bein HaShemashot]] begins from [[Shekiyah]] and ends when three stars are seen, choosing the opinion of Rabba for the beginning of [[Bein HaShemashot]] and Shmuel for the end of [[Bein HaShemashot]]. He answers that really Rabba and Shmuel agree and just describe it differently. This may also be the intent of the Rif (15a) and Rosh 2:23 who say that halacha follows Rabba as a stringency and also quote Shmuel without anyone arguing. See Or Letzion Vol. 1 YD 1:10 who offers a novel interpretation of the opinion of the Rambam that he holds like Rabbi Yose (see there for the halachic implications). See also Beur Halacha 416 who paskens like Rabbi Yose MeIkar HaDin, as well, and Chazon Ovadia Shabbat Vol. 1 pp. 264.</ref>
#The Gemara rules that if one does a Melacha on [[Shabbos]] for the duration of Bein Hashemashos on Friday evening and Saturday evening, one has certainly violated [[Shabbos]], and must bring a sin-offering. <ref>[[Shabbos]] 35b, Rambam (Hilchot [[Shabbos]] 5:4). This is because if one treats [[Bein Hashemashot]] as day, one broke [[Shabbos]] on Saturday evening. If one treats [[Bein Hashemashot]] as night, one violated [[Shabbos]] on Friday evening. </ref>
#Therefore, one cannot perform Melacha during [[Bein Hashemashot]]. <ref>Mishnah [[Shabbos]] 34b </ref>

==Miscellaneous==
===Toch Kedei Dibbur===

#[[Kedei Dibbur]] is the time it takes to say Shalom Alecha Rebbe,<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)

Dirshu Chadasha 167:7, M.B. 34, note 22 cites various places where M.B. gives conflicting amounts of time. In some places, M.B. writes the time is 3 words of "Shalom Alecha Rebbi," and in other places M.B. writes the time is 4 words of "Shalom Alecha Rebbi U'Mori." Dirshu concludes the main halacha is the three words time as per most achronim and the implication from M.B.</ref> which is about 2 seconds.
#[[Toch Kedei Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedei)</ref>

===Kdei Aniva===

#There are several opinions about how long Kdei Aniva is, however, one doesn't need to be strict to consider it to be longer than 2 gudalin. <ref>How long is kdei aniva? There’s several opinions about this topic:

*Smag- long enough to loop around all the rest of the 7 strings.
*Chayei Adam, Kitzur Shulchan Aruch 9:13- 4 gudalin, Beiur Halacha: 2 gudalin, Eliya Rabba (paskening like Rif and Rosh)- long enough to loop around just 1 string (very short).
*The Beiur Halacha concludes that there’s no need to be strict for more than 2 gudalin. And he says if you have no choice, you can rely on the Eliya Rabba. see [http://ph.yhb.org.il/07-08-11/ Peninei Halacha]</ref>
#How long is the shiur of 2 godlin in practical terms? Chazon Ish : 5 cm, Rav Chaim Naeh: 4 cm. Rav Mordechai Eliyahu (comments to Kitzur 9:13) writes that Kedi Anivah is 4 cm.

===Yad Soledet Bo===

#For purposes of cooking on Shabbat and Kashrut, Yad Soledet Bo is certainly hotter than 113 degrees Fahrenheit. <ref>Shemirat Shabbat Kehilchata (ch. 1, note 3), Badei Hashulchan 92:151</ref> Others are concerned for anything over 110 degrees Fahrenheit and over 160 degrees is certainly yad soledet bo. <ref>Igrot Moshe (OC 4:74 Bishul no. 3), The Laws of Kashrut p. 111). [https://www.yutorah.org/sidebar/lecture.cfm/788227/rabbi-hershel-schachter/kashrus-in-the-home/ Rav Hershel Schachter ("Kashrus in the Home" 2012, about min 30)] quotes Rav Soloveitchik that yad soledet bo is at least 140 degrees and no more than 160 degrees.</ref>

==Links==

*[http://www.yutorah.org/lectures/lecture.cfm/763395/Rabbi_Michael_Taubes/_Parshas_Eikev_How_Big_is_a_Kezayis_ How Big is a Kezayis] by Rabbi Michael Taubes

==Sources==
<references />
[[Category:References]]

When Is the Earliest and Latest Time to Pray?

2024-07-14T23:59:23Z

Schwartz: /* Latest Time */

*Note: For exact times for your location, see [http://www.myzmanim.com/search.aspx myzmanim.com].

==Earliest Times for Shacharit==
=== Korbanot ===
#One should recite [[Korbanot|''korbanot'']] during the day, meaning after [[Olot HaShachar|''alot ha'shachar'']].<ref>Shulchan Aruch O.C. 1:6 </ref>
#If one does not have time, according to Ashkenazim he may say ''korbanot'' at night.<ref>Pri Megadim M"Z 1:6, Mishna Brurah 1:17. Chida (Birkei Yosef 1:13) writes that a person who doesn't have time can say korbanot at night since it is no worse than learning Torah at night. However, he concludes, that according to kabbalah that a person shouldn't read psukim at night really he shouldn't recite korbanot then. </ref> In cases of need, such as a worker who needs to ''daven'' early, according to Sephardim, he can say ''[[korbanot]]'' from 96 seasonal minutes before [[HaNetz|''hanetz'']].<ref>Halacha Brurah 1:16 (based on Sh”t Yacheve Daat 2:8) writes that in cases of need (for example a worker who needs to daven early) it is possible to say [[korbanot]] 96 minutes before [[HaNetz|hanetz]].</ref>
#The ''parsha'' of the ''korban tamid'' and the ''mishnayot'' of the ''korbanot'' should only be said during the day.<ref>Shulchan Aruch O.C. 47:13, Mishna Brurah 47:32</ref>

=== Birchot Hashachar ===
#The earliest time to say [[Birchot HaShachar|''birchot hashachar'']] is from [[Chatzot|''chatzot'']] (halachic midnight).<ref>Magen Avraham 47:13, Kaf HaChaim 46:49, Or Letzion (vol 2, 4:9) </ref> Initially, one should say ''hanoten lesechvi binah'' after ''alot hashachar''. However, if one did say it after ''chatzos'', they fulfilled their obligation.<ref>Rosh (Teshuva 4:1) writes that initially one shouldn't say Hamotzei Lesechvi until Olot. Shulchan Aruch 47:13 codifies this. Magen Avraham 47:13 cites the Arizal who says that all of the brachot can be said after Chatzot but the Magen Avraham qualifies this to where one actually heard the rooster crow. Either way he concludes that it is better to be strict to wait until olot. Mishna Brurah 47:31, Biur Halacha 47:13, and Peninei Halacha (Tefillah 9:5) agree. </ref>

=== Psukei Dzimra ===
#''Baruch sheamar'' should be said after [[Olot HaShachar|''alot hachachar'']] before [[HaNetz|''hanetz'']].<ref>Halacha Brurah 1:16 </ref> Others hold that it may be said before ''alot hashachar.''<ref>Leket Hakemach Hachadash 51:9, Ishei Yisrael (16:15, fnt. 48). Both Leket Hakemach Hachadash and Ishei Yisrael cite Daat Torah 664 and 58:1 who proves from Rashi Brachot 11b that psukei dzimra can be recited before the time for shema.</ref>

=== Tallit and Tefillin ===
#The earliest time that one should put on [[Tallit|''tallit'']] is [[MeSheYakir|''misheyakir'']]''[[HaNetz|.]]''<ref>Shulchan Aruch O.C. 18:3. Shulchan Aruch 18:3 rules that the time to make the bracha on [[Tallit]] is from ''[[MeSheYakir|mesheyakir]]''. There is a dispute among the achronim about when exactly [[MeSheYakir|''mesheyakir'']] is. Because of [[Safek Brachot LeHakel]], Halacha Brurah 18:6 one may not make the bracha earlier than a fifth of an hour (in [[Shaot Zmaniot]]) after [[Olot HaShachar|alot hashachar]]. See Rama 18:3 that one may make a bracha at alot hashachar. Mishna Brurah 18:10 writes that although one should be stringent like the Shulchan Aruch; however, one should not stop someone who does like the Rama. Aruch Hashulchan 18:9 rules according to Rama. The Mishna Brurah adds that even for one who follows the Rama should wait with the bracha until [[MeSheYakir|''mesheyakir'']]. He adds that one who makes a bracha, even at night, need not make another one because there are rishonim who hold that one can make the bracha at night.</ref> Ashkenazim, if they must, may put on ''tallit'' as early as ''alot hashachar''; yet they should not make a ''bracha'' until ''[[MeSheYakir|misheyakir]].''<ref>Rama O.C. 18:3, Mishna Brurah 18:10, Piskei Teshuvot 30:1 </ref> When making the ''bracha'', one should feel the ''tzitzit.''<ref>Rama O.C. 18:3</ref> If one already made a ''bracha'' they should not repeat it, even if they made it before ''alot hashachar''.<ref>Mishna Brurah 18:10</ref>
#The earliest time that one should lay ''tefillin is [[MeSheYakir|misheyakir]].''<ref>Shulchan Aruch O.C. 30:1</ref>
#One who is in a pressing situation and must ''daven'' before the ''zman -'' for if he does not, he will totally miss ''zman tefillah'', may put on ''tallit'' and ''tefillin'' before [[Alot HaShachar|''alot hashachar'']].<ref>Shulchan Aruch O.C. 30:3, Mishna Brurah 30:13, Ishei Yisrael 18:11</ref>
##If one puts on ''tzitzit'' before [[Alot HaShachar|''alot hashachar'']], he should not recite a ''bracha'' until [[MeSheYakir|''misheyakir'']], and then he should feel the ''tzitzit'' after making the ''bracha''.<ref>Shulchan Aruch and Rama O.C. 18:3</ref>
##If one makes this ''bracha'' during ''pesukei dezimra'', it should be said between paragraphs.<ref>Mishna Brurah 51:8 writes that it is permissible to say birchat hodaah during pesukei d'zimra. Shulchan Aruch O.C. 53:3 is clear that one can make a bracha on tallit and tefillin during pesukei d'zimra. Biur Halacha 51:4 s.v. Tzarich writes that it is better to wait for between paragraphs. Here too, there is no rush. Ishei Yisrael (16:6,7; ibid. 18:10,11) agrees.</ref> If [[MeSheYakir|''misheyakir'']] happens between the end of ''pesukei d'zimra'' and ''yishtabach'', one should wait to make the ''bracha'' until after ''[[yishtabach]]''.<ref>Shulchan Aruch O.C. 53:3</ref> However, the ''shliach tzibbur'' should make the ''bracha'' before ''yishtabach''.<ref>Rama O.C. 53:3. Mishna Brurah 53:8 writes that if he only gets the tallit and tefillin after yishtabach he may make the bracha at that time as well. It would be the same here if the time of misheyakir is during yishtabach. </ref> Once the ''shaliach tzibbur'' starts the ''kaddish'' after ''yishtabach'' one can no longer make a ''bracha'' on the ''tallit'' until after ''shemoneh esrei''.<ref>Rama O.C. 54:3; Mishna Brurah 54:13</ref> The ''bracha'' on ''tefillin'' may be said between the paragraphs of ''birchot kriat shema''.<ref>Shulchan Aruch and Rama O.C. 66:2, Mishna Brurah 54:13, Ishei Yisrael 18:11</ref>

=== Shema and Shemoneh Esrei ===
#The ''bracha'' of ''yotzer ohr'' may not be said before ''[[MeSheYakir|misheyakir]]''.<ref>Mishna Brurah 58:17. Piskei Teshuvot (58:10) notes that some are lenient when it is unavoidable. However, Biur Halakha (s.v. Zeman Kriat Shema) notes that this discussion may be irrelevant for men if they are going to only say Pesukei D’zimra before misheyakir and say the bracha on Tzitzit and Tefillin before Yotzer Or, and certainly it is preferable to not begin davening until one can make the bracha on Tzitzit and Tefillin.</ref> If one is ''davening'' before [[MeSheYakir|''misheyakir'']] he should say ''krias shema'' with the ''brachot'', skip over the ''bracha'' of ''yotzer ohr'', and say it after ''shemoneh esrei'', in the proper ''zman.''<ref>Ishai Yisrael 18:10</ref> One who accidentally said ''yotzer ohr'' before [[MeSheYakir|''misheyakir'']] should not repeat it.<ref>Biur Halacha 58:4 s.v. b'lo</ref>
#One who will be unable to recite ''shema'' after [[MeSheYakir|''misheyakir'']] may do so from ''[[Alot HaShachar|alot hashachar]]''.<ref>Shulchan Aruch O.C. 58:3</ref>
#''Shemoneh esrei'' should be recited after ''hanetz.''<ref>Shulchan Aruch 89:1</ref> If it was recited from [[Alot HaShachar|''alot hashachar'']] one has fulfilled his obligation. In a case of need, like for one who is traveling, it is even considered ideal to say ''shemoneh esrei'' from [[Alot HaShachar|''alot hashachar'']].<ref>The Rosh ([[Brachot]] 4:1) writes that even though ideally one should pray at [[HaNetz]] (sunrise) if one prayed after [[Olot HaShachar]] one would have fulfilled one’s obligation. This is also the opinion of many Rishonim including Tosfot 30a (s.v. Avuha), Rambam ([[Tefillah]] 3:7, Sh”t Rambam 27), Rabbenu Yerucham (according to Bet Yosef 89:1) and the Tur 89:1. This is codified in Shulchan Aruch 89:1. Mishna Berura 89:4 writes that if one has a pressing need, he may daven l'chatchila from alot hashachar.</ref>
# The ideal mitzvah is to start praying [[Shmoneh Esrei|''shmoneh esrei'']] of [[Shacharit|''shacharit'']] at ''ha[[Netz HaChama|netz hachama]]'' (sunrise). The practice of those who say ''shemoneh esrei'' of ''shacharit'' at ''[[HaNetz|hanetz]]'' is called ''Vatikin''.<ref>Shulchan Aruch O.C. 89:1, Shulchan Aruch O.C. 58:1, Gemara <nowiki>[[Brachot]]</nowiki> 26a writes the ideal time to pray <nowiki>[[Shacharit]]</nowiki> is at <nowiki>[[HaNetz HaChama]]</nowiki> and that was the practice of the <nowiki>[[Vatikin]]</nowiki> (those who fulfill the מצות early and in the proper time). This is codified by the Rambam (<nowiki>[[Tefillah]]</nowiki> 3:1), Rosh (<nowiki>[[Brachot]]</nowiki> 4:1), Tur and Shulchan Aruch 89:1</ref>
# If a person can either daven at ''[[HaNetz|hanetz]]'' without a minyan or later with a minyan, according to Ashkenazim one may daven at ''[[HaNetz|hanetz]]'' if one is always careful to ''daven'' at ''[[HaNetz|hanetz]]''.<ref>Biur Halacha 58:1 s.v. u'mitzva</ref> According to Sephardim one should daven with a minyan later unless one will pray with ''kavana''.<ref>Yalkut Yosef 89:19</ref>

== One Who Must Work Early ==
#If one needs to travel or in a case of difficulty one may pray [[Shacharit|''shacharit'']] after ''[[Olot HaShachar|alot hashachar]]'' before [[HaNetz|hanetz]], but nonetheless one may not make the ''bracha'' on [[Tallit|''tallit'']] and [[Tefillin|''tefillin'']] or say [[Kriyat Shema|''kriyat shema'']] until [[MeSheYakir|''misheyakir'']]. <ref>*The Rosh (Brachot 4:1) writes that even though ideally one should pray at [[HaNetz|hanetz]] (sunrise) if one prayed after [[Olot HaShachar|alot hashachar]] one would have fulfilled one’s obligation. This is also the opinion of many rishonim including Tosfot 30a (s.v. Avuha), Rambam ([[Tefillah]] 3:7, Sh”t Rambam 27), Rabbeinu Yerucham (according to Bet Yosef 89:1) and the Tur 89:1. This is codified in Shulchan Aruch 89:1.
*There is a minority of Rishonim who hold that in extenuating circumstances one is permitted to pray [[Shacharit]] before [[Olot HaShachar|alot hashachar]]. The basis of this approach is Rashi (Brachot 30a s.v. VeLayaved), Sh”t Raavan (176), and Raavad (quoted by the Sefer Hashlamah).
*Shulchan Aruch 89:8 rules that in cases of extenuating circumstances such as where one has to travel early one may pray [[Shacharit]] [[Shmoneh Esrei|shemoneh esrei]] immediately after [[Olot HaShachar|alot hashachar]] and then say Shema while traveling if one is able to have kavana (proper intent) while traveling. This is also mentioned in Mishna Brurah 89:1.</ref>
##Therefore, a person who needs to pray early in the morning in order to get to work should pray with a [[minyan|''minyan'']] that starts ''davening'' after ''misheyakir'' before ''[[HaNetz|hanetz]]''.<ref>Shulchan Aruch 89:1, Mishna Berurah 89:4 write that when in a pressing situation, one may daven shemoneh esrei from alot hashachar. Shulchan Aruch 18:3 writes that the bracha on tallit should not be said before misheyakir. Shulchan Aruch 30:1 writes that tefillin should not be laid before misheyakir. Shulchan Aruch 58:1 writes that krias shema should not be recited before misheyakir. </ref>
##If that isn't possible then the minyan should use the following schedule: say up to ''birchot [[Kriyat Shema|kriyat shema]]'' without [[Tallit|''tallit'']] and [[Tefillin|''tefillin'']] (except for ''shaliach tzibbur'' who should put on [[Tallit|''tallit'']] and [[Tefillin|''tefillin'']] before ''yishtabach''), when [[MeSheYakir|''misheyakir'']] arrives put on [[Tallit|''tallit'']] and [[Tefillin|''tefillin'']], then continue from there. <ref>[http://www.ou.org/webcast_kosher Rabbi Yisrael Belsky] (OU Kosher Webcast, min 19:30-28:30). Sh"t Igrot Moshe 4:6 writes that a person who needs to make it to work is considered to be in an extenuating circumstance in which Shulchan Aruch 89:8 writes that one may pray [[Shacharit]] after Alot Hashachar See also Iggrot Moshe OC 1:10 and Yechave Daat 2:8.</ref>
#If the choice is to ''daven'' with an early [[minyan|''minyan'']] that ''davens'' before ''[[HaNetz|hanetz]]'' after ''[[MeSheyakir|misheyakir]]'' or to ''daven'' later by oneself, such as in one's office, one should rather ''daven'' earlier with a [[minyan|''minyan'']].<ref>[http://www.ou.org/webcast_kosher Rabbi Yisrael Belsky] (OU Kosher Webcast, min 19:30-28:30), Igrot Moshe 4:6 s.v. im ken, Peri Yitzchak 1:2, Sh"t Yaskil Avdi 5:10, Sh"t Minchat Yitzchak 9:10. Chazon Ish (Ishei Yisrael 13:note 21) ruled likewise. [http://www.ou.org/webcast_kosher Rabbi Yisrael Belsky] (OU Kosher Webcast, min 19:30-28:30) said that if one feels that it is just too dark and one cannot understand what the people are relying on to put on [[Tefillin]] so early one should say up to Baruch SheAmar before traveling and then pray at one’s office.</ref> Some disagree and say that you should ''daven'' on your own rather than ''daven'' before ''hanetz''. <ref>Sh”t Sheilot Shmuel OC 12, Rav Elyashiv (quoted in Avnei Yashfei [[Tefillah]] page 167), Yalkut Yosef ([[Tefilla]] pages 137-139, 89:14). </ref>
#If a person who is not in a rush to ''daven'' before sunrise is needed for a [[minyan|''minyan'']] that is ''davening'' before sunrise there is a dispute whether he is allowed to join or not. <ref>Rav Yosef Shalom Elyashiv quoted in Tefilla Kehilchita page 78 and in Avnei Yashfe (Tefilla page 169 89:14) says that although he can answer for their [[minyan]] he cannot pray with them. This is true even if he is the sixth one who would be praying (a [[minyan]] requires ten but a minimum of six praying at the time) and his refusal to pray would prevent there being a [[minyan]]. Rav Shlomo Zalman Auerbach in Halichot Shlomo 1:5-13 (and Avnei Yishfe p. 169) though ruled that if the refusal to join will prevent the [[minyan]] he may pray with them as long as it is not on a consistent basis. </ref>

===Pre-Misheyakir===

#One who has a choice to ''daven'' with a pre-''[[MeSheyakir|misheyakir]]'' minyan or afterwards by himself, should ''daven'' alone.<ref>Avnei Yishfe p. 167 quotes Rav Elyashiv that it is better to daven oneself later rather than davening before Mesheyakir. He also cites Pri Yitzchak s.v. nachzor 1:2 who agrees.</ref> Some disagree.<ref>Avnei Yishfe p. 168 quotes Rav Ben Tzion Abba Shaul who says that if that's the only minyan available one should daven with a pre-mesheyakir minyan relying on the Pri Chadash rather than daven by oneself. Igrot Moshe 4:6 s.v. im ken agrees.</ref>

===After the Fact===

#If one ''davened'' before [[Olot HaShachar|''alot hashachar'']], one has not fulfilled their obligation. Nonetheless, one should ''daven'' again on condition that if one is exempt then they are ''davening'' voluntarily. <ref>*What is the earliest time for [[Shacharit]]? The Rosh 4:1 writes that even though ideally one should pray at [[HaNetz|hanetz]] (sunrise) if one prayed after [[Olot HaShachar|alot hashachar]] one would have fulfilled one’s obligation. This is also the opinion of many rishonim including Tosfot 30a (s.v. Avuha), Rambam ([[Tefillah]] 3:7, Sh”t Rambam 27), Rabbeinu Yerucham (according to Bet Yosef 89:1) and the Tur 89:1. This is codified in Shulchan Aruch 89:1.
*There is a minority of rishonim who hold that in extenuating circumstances one is permitted to pray [[Shacharit]] before [[Olot HaShachar|alot hashachar]]. The basis of this approach is Rashi ([[Brachot]] 30a s.v. VeLayaved), Sh”t Raavan (176), and Raavad (quoted by the Sefer Hashlamah).
*[Interestingly, the Derisha argues that Rabbeinu Yerucham holds that there are three levels, ideally one should pray at [[HaNetz|hanetz]], it is permissible to pray after [[MeSheYakir|misheyakir]] and it is only effective, after the fact, after [[Olot HaShachar|alot hashachar]].]
*Mishna Brurah 89:2 writes that based on Shulchan Aruch, if one prayed before [[Olot HaShachar|alot hashachar]] one has not fulfilled one’s obligation.
*Yalkut Yosef ([[Tefillah]] pg. 136, see also Sh”t Yechave Daat 2:8) writes that even if one prayed before [[Olot HaShachar|alot hashachar]] one should still pray again at the proper time with a stipulation that if one is not obligated that it should be a voluntary [[prayer]]. So writes Sh”t Otzrot Yosef 5:3.</ref>

== Latest Time for Shacharit ==
#The latest time to say [[Shmoneh Esrei|''shemoneh esrei'']] of [[Shacharit|''shacharit'']] is the end of the fourth hour. <ref>The Mishna (Brachot 26a) writes that the latest time [[Shacharit]] could be said according to Rabbi Yehuda is the fourth hour and according to the Rabbis is the sixth hour. The Gemara (27a) writes that we hold like Rabbi Yehuda because there is a Mishna in Ediyot that supports Rabbi Yehuda. This is codified by the Rif 18a, Rosh 4:1, and Rambam ([[Tefillah]] 3:1). The halacha is brought in Tur and Shulchan Aruch 89:1 </ref>
#If one has not ''davened'' until the end of the fourth hour, one should ''daven'' [[Shacharit|''shacharit'']] before the end of the sixth hour - midday. If one intentionally did not ''daven'' in the first four hours one should still ''daven'' before midday but one should stipulate that if one is exempt that one is ''davening'' a voluntary [[prayer]]. <ref>*The Rif 18a originates that even though we hold like Rabbi Yehuda that the latest time for [[Shacharit]] is the fourth hour one could still pray after the fourth hour and receive the reward for praying (albeit having lost the reward for praying in the proper time). The Rosh 4:1, Rambam (Hilchot [[Tefillah]] 3:1), and Tur 89:1 hold like the Rif.
*The Bet Yosef 89:1 writes that it seems as though the Rosh and Rif base their halacha on the general language of the gemara (Brachot 26a) “one could pray all day and receive reward for [[prayer]] but would lose the reward for [[prayer]] in its proper time.” Because this phrase was the gemara’s way of explaining the halacha of [[Tashlumin]], the Bet Yosef, rules that according to the Rif and Rosh one would not be able to pray after the fourth hour if a person intentionally did not pray in the first four hours.
*However, the Rambam and Tur 89:1 hold that if a person intentionally prayed after the fourth hour he still receives reward for [[prayer]]. The Bet Yosef 89:1 explains that the Rambam tried to minimize the dispute between רבנן and Rabbi Yehuda so that there would not be an argument as to whether one totally fulfills the mitzvah or does not fulfill it at all in the period between the fourth and sixth hour. Rather they both agree that it is still time for [[Shacharit]] but according to Rabbi Yehuda one who prays at that time only receives reward for [[prayer]] but not that of [[prayer]] in its proper time while רבנן hold that one would also receive the reward of it being in its proper time. According to this explanation, one should be able to pray in this period even if one intentionally did not pray beforehand.
*Additionally, if one holds like the Rif then one would be able to daven even between six and sixth and a half, while according to the Rambam one should only be able to pray as long as there is some opinion which considers it the time for [[Shacharit]]. The Bet Yosef adds that the Rashba agrees with the Rambam. (It seems that the Bet Yosef understands the Rashba to say that you certainly may not pray during the half hour after [[Chatzot]]. The Bach argues that the Rashba meant something else entirely, namely that one should pray the [[Tashlumin]] right after having prayed the obligatory [[Tefilla]].)
*The Mishna Brurah 89:6 writes that because of the dispute one should still pray after the fourth hour even if one intentionally missed praying earlier but nonetheless should stipulate that if one is exempt, one should be considered praying voluntarily. Yalkut Yosef 89:5 agrees.</ref>
#One may not ''daven'' past the end of the sixth hour, but rather one should wait to say [[Tashlumin|''tashlumin'']] at [[Mincha|''mincha'']].<ref>Rama O.C. 89:1 (based on the explanation of the Bet Yosef of the Rambam and Tur, see the [[#cite_note-11|previous footnote]])</ref>

==Times for Mincha==
===Ideal Time for Mincha===

#The ideal time to ''daven'' [[Mincha|''mincha'']] is after nine and a half hours ([[Mincha|''mincha'']] ''ketana''), however, one fulfills one’s obligation by ''davening'' from six and a half hours (''[[mincha]] gedola''). <ref>*Rambam (Tefillah 3:2) writes that since they instituted Tefillah corresponding to korbanot the primary time for mincha is mincha ketana, 9.5 hours in the day but one fulfills one's obligation anytime after mincha gedola, 6.5 hours. The Tur 233:1 argues that the primary time to pray [[Mincha]] is after six and a half hours since it is the time when a korban mincha is fit. Shulchan Aruch O.C. 233:1 follows the Rambam. The Mishna Brurah 233:1 also holds like the Rambam but adds that there are some rishonim who allow one to pray earlier and in certain cases (see further) one may pray earlier. Kaf HaChaim 233:1, Yalkut Yosef (Brachot page 637) and Halichot Olam (vol 1 pg 253) concur with Mishna Brurah. Aruch Hashulchan 233:12 writes that ideally one should daven after mincha ketana but for any small reason one could even initially daven mincha gedola.
*Kaf Hachaim 233:3 adds that really the best time is after plag mincha, 10.45 hours into the day.
*See the BeYitchak Yikra 233:1 (notes of Rav Nevinsal on Mishna Brurah) who adds that the Rambam holds that the only preferable time is after [[Mincha]] ketana before plag [[Mincha]] (10 ¾ hours) and it would be preferable to say [[Mincha]] individually at [[Mincha]] gedola rather than with a [[minyan]] at [[Mincha]] ketana after plag [[Mincha]]. Nonetheless, he agrees that the minhag is not like this.</ref>

====When it is Ideal to Daven Mincha Gedola====

#In many yeshivos the minhag is to ''daven'' ''mincha gedola'' to avoid breaking up a ''seder,'' a fixed section of learning.<ref>Piskei Teshuvot 233:2. [https://www.torahanytime.com/#/lectures?v=74381 Rav Yitzchak Yosef (Motzei Shabbat Shemot 5779 approx min 30)] explained that his father used to say mincha only after mincha ketana but later said it at mincha gedola. He recommended it for a yeshiva setting. He also explained that the Rif and Rosh hold that it is permitted even initially to say mincha at mincha gedola.</ref>
#If one needs to travel or have a meal (which is forbidden before ''davening'' once the time for [[Mincha|''mincha'']] arrives), one can ''daven'' from after six and a half hours. <ref>Mishna Brurah 233:1 writes that if one needs to travel, have a meal, or one will only be able to make a [[minyan]] for [[Mincha]] earlier, then one can pray from after six and a half hours. Kaf HaChaim 233:1 also writes that there are those who are lenient to pray early if there is a need. Yalkut Yosef ([[Brachot]] page 637) and Halichot Olam (vol 1 pg 253) writes that it is preferable to pray after six and a half hours in order to avoid having a meal before praying [[Mincha]] (after the time for [[Mincha]] has arrived). </ref>
#If one will only be able to make a [[minyan|''minyan'']] for ''[[mincha]] gedola'' (after six and a half hours) and one will not make a [[minyan|''minyan'']] for ''mincha ketana'' (after nine and a half hours), it is preferable to ''daven'' with a [[minyan|''minyan'']] after six and a half hours. <ref>Mishna Brurah 233:1, Yalkut Yosef ([[Brachot]] pg 639). [https://www.torahanytime.com/#/lectures?v=74381 Rav Yitzchak Yosef (Motzei Shabbat Shemot 5779 min 43)] said that although the Shoel Vnishal held that it is better to daven by oneself than to daven at mincha gedola the halacha doesn't follow that opinion.</ref>

===Earliest Time===

#If one ''davened'' prior to six and a half hours, according to many, one has not fulfilled one’s obligation; however, some say that one has fulfilled one's obligation after the fact. Therefore, one should not ''daven'' again.<ref>Mishna Brurah 233:2 writes that it is implied from Shulchan Aruch 233:1 that one has not fulfilled one's obligation (and is agreed upon by many achronim); however, there are some achronim who say that after the fact one has fulfilled one’s obligation. Kaf HaChaim 233:2 quotes the dispute of the achronim but concludes that because [[Tefillah]] is derabbanan one does not have to pray again. Ishei Yisrael 27:5 agrees. See Ishei Yisrael 27 footnote 10. </ref>

===Latest Time for Mincha===

==== After Plag HaMincha ====

# According to Rabbi Yehuda, the latest time for ''mincha'' is ''plag hamincha -'' ten- and three-quarter hours. From then on begins the time for ''arvit''. According to Rabbanan, the cutoff point is nightfall.<ref name=":0" /> Halacha allows one to follow either opinion, however, one must be consistent and always follow the same opinion.<ref name=":1" /> Thus, one who is accustomed to ''davening arvit'' before ''shkiya'' must always ''daven mincha'' before ''plag.''<ref>Shulchan Aruch O.C. 233:1, Rama O.C. 233:1</ref> In extenuating circumstances or if one forgot to ''daven mincha'', they may ''daven'' after ''plag;''<ref>Rama O.C. 233:1</ref> however, they should be particular to ''daven arvit'' after ''tzet hakochavim'' on that night.<ref>Mishna Brurah 233:11,13</ref>
# Some write that, even according to Rabbanan, one must ''daven mincha'' before ''plag.<ref>Aruch Hashulchan O.C. 233:4-9</ref>'' This is not the accepted custom.

====After Sunset====

#One who ''davens arvit'' after ''tzet'' may ''daven mincha'' up until ''shkiya.''<ref>The time period of ''bein hashmashot'' may be considered day, thus, If one ''davens arvit'' after ''shkiya'' but before ''tzet'' it would present a contradiction. Igrot Moshe II:60 writes that it may not be a contradiction to ''daven arvit'' at a time when one would no longer ''daven mincha.'' Thus, he writes, that one may ''daven'' with a ''minyan'' that is ''davening arvit'' at that time, if that is his only opportunity to ''daven'' with a ''minyan.'' </ref>
#The Gemara relates, that there is a halachic period of time during twilight called ''"bein hashmashot."'' This period of time is, halachically, a mix of day and night. Before that time it is day and after which it is night.<ref>Gemara Shabbat 34b. There is a dispute there between Rabbi Yehuda Rabbi Nechemia and Rabbi Yosi. Rabbi Yehuda says that ''bein hasmashot'' begins when the sun (''lit.)'' sinks and lasts until the upper part of the eastern sky is dark. Rabbi Nechemia says that ''bein hashmashot'' starts when the sun sinks and lasts for the duration of 0.5 ''mil.'' Rabbi Yosi says that ''bein hasmashot'' lasts for "a blink of an eye". Gemara Shabbat 35b quotes Rav Yehuda in the name of Shmuel that when there is one star it is still day, two stars is ''bein hashmashot'', three stars is night. Gemara Shabbat 35a writes that the halacha is in accordance with both Rabbi Yehuda and Rabbi Yosi. Rif Shabbat Chap.2, Rosh Shabbat Chap 2:23, and others maintain that the halacha follows Shmuel as well.

*These are the bases for the discussion amongst the ''poskim'' as to the time of ''bein hashmashot''. To see how this translates into the common halacha and for a full discussion see Hazmanim B'halacha Chap. 40</ref>
#There is a great dispute regarding the time for ''bein hashmashot'' and the time for ''tzet hakochavim'' with many ramifications in halacha. The ''geonim'' write that ''bein hashmashot'' begins at sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim.''<ref>Ginzei Kedem V pg.37, See Teshuvat Maharam Alshakar 96 quoting Teshuvat Rav Sherira Goan and Rav Hai Goan. For a more complete list see Hazmanim B'halacha - Rav Benish Chap. 41 3-5.

*Notably, Gra O.C. 261:11, Y.D. 262:9, and Rav Shneur Zalman of Liadi (Baal HaTanya) Siddur - Seder HaChnosat Shabbat, ''pasken'' in accordance with this view and it has thus become accepted halacha in most circles.

*Notable exceptions to this were Rav Yoel Teitelbaum of Satmar and Rav Yekusiel Yehuda Halberstam of Tzanz-Klausenburg who wrote that the halacha is in accordance with Rabbenu Tam. See Divrei Yoel 18, Shefa Chaim - Kovetz Igros Kodesh I:11-20

*Hazmanim B'halacha Chap.44:5 writes that regarding the start of Shabbat even the Satmar Rav and the Tzanz-Klausenburger Rav went in accordance with the ''geonim.''
*Igrot Moshe IV:62 writes that we are not able to resolve a dispute between ''rishonim'' and we must be stringent according to both views.</ref> Rabbenu Tam was of the opinion that ''bein hashmashot'' begins 3.25 ''mil'' after sunset and lasts for 0.75 ''mil'' at which time it is ''tzet hakochavim''.<ref>Sefer HaYashar New Edition 221, Tosfot Shabbat 35a ''s.v''. trei, Tosfot Pesachim 94a ''s.v.'' Rabbi Yehudah. Many other ''rishonim'' agreed with Rabbenu Tam, see Hazmanim B'halacha Chap 42:6-10 for a complete list.</ref><ref>There are additional opinions as well; yet they are not the accepted halacha.

*Sefer Yeraim 274 writes that ''bein hashmashos'' begins 0.75 ''mil'' before sunset and lasts until sunset at which time it is night. Biur Halacha 261:2 ''s.v. mitchilas'' writes that it is worthwhile to start ''Shabbat'' before that time.

*Sefer Raavan 2 writes that ''bein hashmashot'' begins at sunset and lasts 5 ''mil'' until ''tzet hakochavim.''

*See Hazmanim B'halacha Chap 41 for a complete discussion.</ref>
#Some ''poskim'' write, that even according to Rabbenu Tam, in areas of a lower latitude where three medium-sized stars are visible earlier, ''tzet hakochavim'' would be at the time when the stars are visible.<ref>Minchas Kohen 2:5 ''s.v.'' ''she'im'', Biur Halacha 261:2 ''s.v. kodem'' and Igros Moshe O.C. IV:62 agree. Rav Moshe writes that in New York the time for ''tzet'' according to Rabbenu Tam is 50 minutes after ''shkiya''; however, he writes that it is proper for G-d fearing Jews to wait 72 minutes to end Shabbat, as was the custom in Europe. See Hazmanim B'halacha Chap. 42 for a complete discussion.</ref>
#One must ''daven mincha'' during the daytime. Since ''bein hashmashot'' begins at sunset according to the ''geonim'', one should ''daven mincha'' before sunset. After the fact, opinions differ regarding how late one can still ''daven'', and at what point should instead say [[Tashlumin|''tashlumin'']] at [[Maariv|''maariv'']]. Factors that come into consideration include whether or not one can rely on Rabbenu Tam after the fact, and whether or not one may ''daven'' during ''bein hashmashot'', as it may still be day.<ref>Rav Nevinsal on Mishna Brurah 233:14 writes that someone who doesn't always follow Rabbenu Tam on ending Shabbat can not daven mincha after sunset even after the fact. Also, Avnei Darech 8:200 quotes Rav Shlomo Zalman Auerbach as holding that one may not daven mincha after sunset. [http://www.eretzhemdah.org/newsletterArticle.asp?lang=he&pageid=48&cat=1&newsletter=3705&article=7631 Bmarah Habazek 3:14] writes that one shouldn't daven after sunset and just daven tashlumin. [https://www.yeshiva.co/ask/58222 Rav Belsky] held that it is possible to daven up to 9 minutes after sunset based on Rav Moshe. See Igrot Moshe 1:24 who writes that one shouldn't pray mincha after sunset. See further Igrot Moshe 4:62. Piskei Teshuvot 233:8 writes that the Minhag in Eretz Yisrael is that one may lenient to Daven mincha during Bein Hashmashot (according to the opinion of the Ge'onim) which is up to 13 and one half minutes after shkia'ah.</ref><ref>To illustrate this point: Igrot Moshe IV:62 writes that the first nine minutes after ''shkiya'' are considered a ''sfek sfaika and'' regarding a ''bris milah'', we could consider the baby as born on the earlier day. The ''sfek sfaika'' is that maybe the halacha follows Rabbenu Tam, and even not, it may be day according to the ''geonim.'' (Rav Moshe calculates that ''tzet hakochavim'' of the ''geonim,'' in New York, is nine minutes after ''shkiya'').</ref>
#Many Chassidim maintain that it is optimal to ''daven'' ''mincha'' up until the ''bein hashmashot'' of Rabbenu Tam, which is 3.75 ''mil'' after ''shkiya''. There are some who hold that it is even optimal to ''daven'' during ''bein hashmashot'' of Rabbenu Tam.<ref>For a discussion on this see Piskei Teshuva 233:6-8.</ref>
#If one's only options are to either to ''daven'' ''mincha'' before sunset himself or to ''daven'' with a ''minyan'' after sunset, it will depend on if he is Ashkenazi or Sephardi. Ashkenazim hold that one should ''daven'' oneself on time before sunset,<ref>Mishna Brurah 233:14 writes that it is better to pray Mincha before shkiyah without a minyan than to pray with a minyan after shkiyah. In an extenuating circumstance he allows davening mincha until 3.25 mil after shekiya based on the Shulchan Aruch. [https://ph.yhb.org.il/02-24-04/#_te01ftn24_3 Peninei Halacha (Tefillah 24:4)] holds that one can follow the Mishna Brurah who is based on Rabbenu Tam and even though we do not follow Rabbenu Tam since many agree with him. However, Kuntres Seyda Lderech p. 39 quotes Chazon Ish that one should not daven mincha after sunset even in extenuating circumstances or after the fact. Dirshu 233:22 cites this as well from Ishrei Yosher (Nezikin n. 94). Rav Nevinsal on Mishna Brurah 233:14 writes that someone who doesn't always follow Rabbenu Tam on ending Shabbat can not daven mincha after sunset even after the fact. Also, Avnei Darech 8:200 quotes Rav Shlomo Zalman Auerbach as holding that one may not daven mincha after sunset. [http://www.eretzhemdah.org/newsletterArticle.asp?lang=he&pageid=48&cat=1&newsletter=3705&article=7631 Bmarah Habazek 3:14] writes that one shouldn't daven after sunset and just daven tashlumin. [https://www.yeshiva.co/ask/58222 Rav Belsky] held that it is possible to daven up to 9 minutes after sunset based on Rav Moshe. See Igrot Moshe 1:24 who writes that one shouldn't pray mincha after sunset. See further Igrot Moshe 4:62.</ref> while Sephardim hold that one can wait to ''daven'' with the ''minyan'' as long as it is within 13.5 minutes after sunset.<ref> Chacham Ben Zion Abba Shaul (cited in Ishei Yisroel page 296) and Chacham Ovadia Yosef (Yechave Daat 5:22) write that it is preferable to pray with a minyan as long as they are praying within the first thirteen and a half minutes after sunset. Rabbi Meir Mazuz in Bayit Neeman 1:25 p. 146 s.v. miyhu agrees even though we don't accept Rabbeinu Tam since this case is an minhag to pray during Ben Hashemashot. Yalkut Yosef 233:3 and Halacha Brurah 233:6 agree. </ref>

====Finishing After Sunset====

#Sephardic ''poskim'' hold that one can start ''mincha'' before sunset even if one knows that one will not finish until after sunset.<ref>Rav Hai Goan and Rav Sherira Goan in Teshuvot Hagoanim (Lik, 51) Yabia Omer OC 7:34 quoting the Geonim (Teshuva Mosafiya n. 51)</ref> Some Ashkenazic ''poskim'' agree,<ref>Aruch Hashulchan 110:5 based on Tosfot Brachot 7a s.v. shilmaleh</ref> while many disagree.<ref>Kuntres Seyda Lderech p. 39 quotes Chazon Ish that one should not start mincha before sunset if one knows that one will not finish until after sunset. He cites that this is like Mishna Brurah 89:1 that one can't start tefilla before the zman and finish after the zman. He cites that Rav Chaim Kanievsky, Rav Aryeh Leib Shteinmann, and Rav Nosson Geshtetner agreed. </ref>
#Initially, all of the ''shemoneh esrei'' and ''chazarat hashatz'' should be finished before sunset.<ref>Yabia Omer 7:34 in fnt., Halacha Brurah 233:6. Yalkut Yosef 233:3 implies this as well as he writes that if it is after sunset the congregation shouldn't skip chazarat hashatz; they should say it as long as it is still within 13.5 minutes from sunset. Although Chacham Ovadia (Yabia Omer 7:34) wrote that it is permitted even initially to pray after sunset during the ben hashemashot, in the footnote he implies otherwise. He writes that it is only for someone who didn't have a chance to pray earlier may pray then. This is also how Halacha Brurah 233:6 understands the opinion of his father that it is preferable (''mitzvah min hamuvchar)'' to pray before sunset. </ref>

===Tachanun===

#If one reaches ''tachanun'' during ''bein hashmashot,'' there is a debate amongst the ''poskim'' if it should be recited with ''nefillat apayim''.<ref>Mishnah Brura 131:16 states that the discussion of whether or not ''tachanun'' may be said at night refers to reciting it with ''nefillas apayim.'' Merely reciting the chapter may be done at night. Mishnah Brura 131:17 holds one should say it with ''nefillas apayim''. Rav Avigdor Neventzal in B’Yitzhak Yikareh on Mishna Brura (footnote to 131) quotes Rav Shlomo Zalman Auerbach who thinks one should not. </ref>
#If [[mincha|''mincha'']] lasts until after ''tzeit hakochavim'', [[tachanun|''tachanun'']] is not recited with ''nefillat apayim''.<ref>Kitzur Shulchan Aruch 69:8, Mishna Brurah 131:17. Mishnah Brura 131:16 writes that although ''tachanun'' is not said with ''nefillas apayim''; nevertheless, the ''mizmor'' of ''tachanun'' may be recited even after ''tzeit hakochavim.'' </ref>
#Some ''poskim'' write that even the ''mizmor'' of ''tachanun'' must not be said, even during ''bein hashmashot.''<ref>Kaf HaChaim 131:51,52</ref>

===If One Hears Kedusha of a Late Mincha Minyan===

#According to many authorities, one who ''davened'' ''arvit'' before nightfall, may answer ''kedusha'' to a ''minyan davening mincha.'' This applies even on Friday night.<ref>Magen Giborim 237:1, Amudei Esh 3:19, Yaskil Avdi 5:30, and Tiferet Adam 8 hold that even after saying [[maariv]] one may answer [[kedusha]] of a [[minyan]] saying [[mincha]] unlike the opinion of the Erech Shai 236, Yagel Yacov, and Aruch HaShulchan 232. Yismach Lev 16 writes that even on Friday night if one said [[maariv]] one may still answer [[kedusha]]. Sh"t Tzitz Eliezer 10:16 and Sh"t Yabia Omer 6:21 agree with the Yishmach lev.</ref>

==Times for Arvit (Maariv)==
===Earliest Time for Arvit (Plag Hamincha)===

#One who ''davened'' ''arvit'' prior to ten- and three-quarter hours has not fulfilled his obligation and must ''daven'' again.<ref>Mishna Brurah 233:10, Kaf HaChaim 233:11 as is implied by Shulchan Aruch 233:1 </ref>
#One who means to ''daven arvit'' after ''tzeit hakochavim'' but mistakenly ''davened'' from ''plag hamincha'', must ''daven'' again at the proper time.<ref>Gemara Brachot 27b writes that on Friday afternoon someone who made a mistake and said [[Arvit]] early thinking it was nighttime according to Abaye he would have to pray again. The Rabbenu Yonah 18b s.v. Rav explains that since one made a mistake and did not intend to pray [[Arvit]] early one does not fulfill one’s obligation. The Magen Avraham 263:26 and Mishna Brurah 263:55 agree that this halacha applies equally to a weeknight as to Friday night. </ref>

=== Ideal Time for Arvit (Tzet Hakochavim) ===
#[[Kriyat Shema|''Kriyat shema'']] must be recited after [[Tzet HaKochavim|''tzet hakochavim'']].<ref>Mishna Brachot 2a, Shulchan Aruch OC 235:1, Kitzur Shulchan Aruch 70:1</ref> Since ''kriyat shema'' is biblical, one should be vigilant to recite ''shema'' after ''tzet hakochavim'' of Rabbenu Tam.<ref>Mishna Brurah 235:4, Igrot Moshe YD 4:48:4</ref>
#Ideally, one should ''daven'' [[Arvit|''arvit'']] after [[Tzet HaKochavim|''tzet hakochavim'']];<ref>Mishna Brurah 233:9, Kitzur Shulchan Aruch 70:2</ref> however, the ''minhag'' of many places is to ''daven'' ''arvit'' immediately after sunset.<ref>Igrot Moshe II:60 writes that it may not be a contradiction to ''daven arvit'' at a time when one would no longer ''daven mincha.'' Thus, he writes, that one may ''daven'' with a ''minyan'' that is ''davening arvit'' at that time, if that is his only opportunity to ''daven'' with a ''minyan.'' Mishna Brurah 235:12 writes that fortunate is the person who can daven with a congregation after Tzet Hakochavim which is the correct time.</ref>
#Many are accustomed to ''davening'' ''mincha'' before ''shkiya'', taking a short break, and ''davening arvit'' after ''tzet'' of the ''geonim'' which can be as early as nine minutes after ''shkiya.''<ref>According to Igrot Moshe IV:62, see Ishei Yisrael Chap. 28 footnote 2</ref>
#A ''tzibur'' may ''daven'' both ''mincha'' and ''arvit'' between ''plag'' and ''shkiya'' if it will be too difficult to reconvene after everyone goes home.<ref>Mishna Brurah 233:11</ref>

===Arvit Before Sunset If One Davened Mincha Early===

#According to Rabbi Yehuda, the latest time for ''mincha'' is ten- and three-quarter hours. From then on begins the time for ''arvit''. According to Rabbanan, the cutoff point is nightfall.<ref name=":0">The Mishna ([[Brachot]] 26a) writes that according to Rabbi Yehuda one must pray [[Mincha]] prior to ten and three quarter hours while according to Rabbanan [[Mincha]] may be said until nighttime. Tosfot Brachot 27a s.v. Ta Shma writes that according to Rabbi Yehuda the earliest time to say ''arvit'' is ten- and three-quarter hours while according to Rabbanan the earliest time is nighttime. [This is also evident in the Gemara there (27a-b) and the upcoming Rishonim. The Maharsha (27a s.v. Tah Shma) asks why Tosfot needed to prove something which was so obvious from the Gemara.] </ref> Halacha allows one to follow either opinion, however, one must be consistent and always follow the same opinion.<ref name=":1">The Gemara (27a) writes that since there is no explicit ruling as to whom the halacha follows, one who follows Rabbi Yehuda has done properly and one who follows Rabbanan is correct too. Rabbeinu Yonah ([[Brachot]] 18b s.v. DeAved) writes that one must consistently follow the same opinion. This is also opinion of the Rosh ([[Brachot]] 4:3) quoting a Gaon. Additionally, the Kesef Mishna ([[Tefillah]] 3:4) says that this is implicit in the Rambam and furthermore that it is the simple explanation of the words of the Gemara. Tur and Shulchan Aruch 233:1 codify the opinion of Rabbeinu Yonah. </ref>
#The general ''minhag'' is to ''daven mincha'' until sunset. Accordingly, one may only begin to ''daven arvit'' after that time.<ref>Rabbenu Yona Brachot 18a s.v. tefillat, Mordechai Brachot IV:90 quoting Rav Hai Goan, and others write that nightfall refers to ''shkiya.'' Rambam (Hilchot Tefillah 3:4) writes this as well. See Hazemanim B'Halacha - Rav Benish Chap. 34:6 and footnotes 16-19.

*Rashi Brachot 26a s.v. Ad Chashecha according to Shaagat Aryeh 17, Ra'av Brachot 4:1, and others explain "nightfall" to be ''tzet hakochavim.'' See Zemanim B'Halachah - Rav Benish Chap 34:7 and footnotes 22-28.
*Rama O.C. 233:1 writes that according to the Rabbanan one may ''daven mincha'' until ''tzet hakochavim''.
*Shulchan Aruch O.C. 233:1 writes that the ''minhag'' is to ''daven mincha'' until ''shkiya'' and one may not ''daven arvit'' before ''shkiya''.
*Mishna Brurah 233:8,9,14 understands that Shulchan Aruch means the second ''shkiya'' and that Shulchan Aruch and Rama both agree that one may ''daven mincha'' up until Rabbenu Tam's ''bein hashmashot'' which is 3.25 ''mil'' after sunset. That which Shulchan Aruch and Rama write ''"shkiya"'' and "''tzet hakochavim"'' is not exact and means "almost up until that time." Mishna Brurah understands that the cutoff of the Rabbanan is ''tzet'' but since ''bein hashmashot'' is a time of ''safek'', one may not ''daven'' neither ''mincha'' nor ''arvit'' during that time. Thus, ''mincha'' must be recited before 3.25 ''mil'' after sunset and ''arvit'' must be recited after 4 ''mil''. However, the Mishna Brurah, quoting many ''poskim,'' see Shaar Hatziyun 233:18, writes that others argue on the Shulchan Aruch and Rama and according to them one must not ''daven mincha'' after ''shkiya.'' The Mishna Brurah 233:14 writes that one should be stringent in accordance with this view. Nevertheless, he adds that one who is under extreme duress may be lenient to ''daven'' until 3.25 ''mil'' after ''shkiya'', but should ''daven'' as early as possible so as not to enter into a ''safek shkiya''.
*Mishna Brurah 235:12 writes that it is optimal to ''daven arvit'' after ''tzet'' - earlier than that, during ''bein hashmashot,'' is a ''safek''. Biur Halacha 233:1 ''s.v. d'haynu'' writes that one who is ''davening'' ''mincha'' after ''shkiya'' should make a condition: if this is still the time for ''mincha'' then this ''tefilla'' will be for ''mincha'' and the next will be for ''arvit''; yet if it is now the time for ''arvit'', this ''tefillah'' will be ''arvit'' and the next one will be a ''tashlumin'' for ''mincha.''
*Aruch HaShulchan 233:6-9 writes that one who is able must ''daven mincha'' before ''plag''. One who is not able to ''daven'' then must be careful to ''daven'' before ''shkiya'', despite the fact that there are ''rishonim'' who say that one may ''daven'' until ''tzet''.
*Igrot Moshe I:24 writes in accordance with Mishna Brura that one should not ''daven mincha'' after ''shkiya'' unless under duress. Rav Moshe adds that in America the ''zman'' of Rabbenu Tam is certainly less than an hour after ''shkiya.'' Thus, taking ''bein hashmashot'' into account, the time for ''mincha'' cannot be later than 48 minutes after ''shkiya'', and possibly it is in fact earlier.
*Orchot Rabbeinu III pg. 225 quotes the Chazon Ish as saying that if one knows that he won't finish ''shemoneh esrei'' before ''shkiya'' then he should not start ''davening''; rather he should ''daven'' ''maariv shemoneh esrei'' twice as ''tashlumin.''
</ref> In extenuating circumstances, one may ''daven arvit'' before sunset if on that day he ''davened mincha'' before ''plag hamincha''. Although he usually follows the Rabbanan, it is considered as if on that day he followed Rabbi Yehuda.<ref>The Rabbenu Yonah (18b s.v. DeAved) writes that one should always follow Rabbanan (which was the minhag of his time and place) but nonetheless, after the fact if one prayed [[Arvit]] after Plag [[Mincha]] one has fulfilled one’s obligation. This is quoted in Bet Yosef 233:1 and codified in Shulchan Aruch O.C. 233:1. The Shulchan Aruch 233:1 rules that in extenuating circumstances one may pray [[Arvit]] before nighttime even though one always follows Rabbanan. Mishna Brurah 233:11 writes that this is only permissible if that day itself one already prayed [[Mincha]] prior to ten and three quarter hours.</ref>
#If the only minyan for ''arvit'' ''davens'' before sunset, after ''plag hamincha,'' one should daven with them<ref>The Biur Halacha 235:1 cites the Gra who held that it is better to daven privately on time rather than daven with the congregation early. However, in Shaar Hatziyun 235:16 he quotes the Derech Hachayim that if one prayed mincha before plag and the only option is to daven after plag maariv with a minyan or after tzeit without a minyan, it is better to daven with a minyan after plag. If he didn't daven ''mincha'' until after ''plag'', it is better to ''daven maariv'' oneself than to daven in a minyan before sunset and contradict oneself within one day.</ref> and repeat ''shema'' after ''tzet hakochavim''. Some say to skip ''birchot kriyat shema'' and recite them after ''tzet hakochavim'' with ''shema''.<ref>Rabbenu Yonah Brachot 1b writes that if the congregation is davening before the time for Shema one should daven with them even though he won't fulfill his obligation of ''shema'' and will have to repeat it later. He then quotes Rav Hai Goan who says that one should only say ''shema'' with them without kavana to fulfill one's obligation but skip birchot kriyat shema. The Shulchan Aruch OC 235:1 rules like the Rabbenu Yonah but the Mishna Brurah 235:12 mentions the practice of the Rav Hai Goan. Rav Moshe Feinstein in Igrot Moshe OC 2:60 agrees that one can follow either opinion whether to daven everything or just Shema without kavana and Shemona Esrei and then say Shema with Kriyat Shema with Brachot afterwards. He writes that one shouldn't follow the Gra unless one always does according to his opinion.</ref>
# Many say, that for Sephardim, ''plag'' is 1.25 hours before ''tzet hakochavim'' of the ''geonim -'' which is 13.5 minutes after ''shekiya.'' They should not follow the ''plag'' of the Gra; 1.25 hours before sunset.<ref>Yalkut Yosef (Shabbat v. 1 p. 168 263 fnt. 62; 235:1; 267:12) and Ben Ish Chai Vayahakel n. 8. In all of those places the calculation of Plag is made from Tzet according to the Geonim. Thereby, the Sephardi Plag Mincha is generally between 10 and 20 minutes after the Gra plag. Yalkut Yosef (Shabbat 1-3, 5771 edition, pp. 143-146) writes that a person can pray arvit as early as plag mincha. However, he defines plag hamincha as 1.25 hours before tzet hakochavim of the geonim. The hours are calculated from olot to tzet of the geonim. He addresses that for kriyat shema in extenuating circumstances it is acceptable to rely upon the Gra zmanim, but not for the brachot of avrit because of safek brachot lhakel. Also, one can't light Shabbat candles before 1.25 hours before tzet of geonim. He rebuts an attack that we must follow the Gra zmanim since we light candles before plag of Rabbenu Tam. He answers that we follow the plag of the Ben Ish Chai which is 1.25 hours before tzet of the geonim but not the Gra's plag. on p. 144 he writes that it is a bracha levatala to pray avrit after plag of the Gra.
*See also [https://www.torahanytime.com/#/lectures?v=81670 Rav Yitzchak Yosef (Motzei Shabbat Pesach 5779 min 37)] who said that the schedules which print plag mincha 1.25 hours before shekiya (Gra) are causing Sephardim to say brachot levatalot when they daven arvit right after plag. Rather they need to daven after plag which is 1.25 hours before tzet. Tzet is only 20 minutes (13.5 zmaniyot minutes) so our plag is less than 20 minutes after their plag but starting arvit before then is a bracha levatala for Sephardim. They should print the plag according to Sephardim.
*See also [https://www.torahanytime.com/#/lectures?v=55391 Rav Yitzchak Yosef (Motzei Shabbat Bo 5778 min 25)] who said that it is a bracha levatala to daven Arvit after Plag of the Gra according to Rabbenu Tam and we are strict for Rabbenu Tam.
*[https://www.torahanytime.com/#/lectures?v=60107 Rav Yitzchak Yosef (Motzei Shabbat Emor 5778 min 28)] said that since the minhag is that we follow the geonim for zmanim, the minhag is to pray mincha before Plag of the geonim and arvit after Plag of the geonim, even though according to Rabbenu Tam it is a bracha levatala since it is day.</ref> Thereby, the Sephardi ''plag hamincha'' is generally between 10 and 20 minutes after the Gra ''plag''. See the [https://play.google.com/store/apps/details?id=net.calj.android CalJ App] for calculation of this ''zman''. Others say that even Sephardim can calculate ''plag hamincha'' according to the Gra.<ref>Kaf Hachaim 233:7, Halacha Brurah v. 14 teshuva 7. Halacha Brurah writes that there's no safek brachot to light candles after plag of the gra or daven arvit after that plag since that is the minhag and there's no safek brachot where there is a minhag. He rejects the position of Ben Ish Chai that we calculate from Olot to Tzet of Geonim because that is definitely not the view of the Geonim. Rather the Geonim would calculate their zmanim in accordance with Gra.</ref>

===Early Arvit on Friday Night===

#Regarding praying [[Arvit|''arvit'']] early on Friday night see [[Making early Shabbat|Making Early Shabbat]].

===Mincha/Arvit Between Plag and Sunset===

#An individual may not ''daven mincha'' after ''plag hamincha'' and ''arvit'' before sunset on the same day.<ref>Shulchan Aruch 233:1, Mishna Brurah 233:11</ref>
#A [[minyan|''minyan'']] may be lenient to ''daven'' both [[Mincha|''mincha'']] and [[Arvit|''arvit'']] between ''plag hamincha'' and sunset, even though it is a self-contradictory practice following both Rabbanan and Rabbi Yehuda.<ref>Mishna Brurah 233:11 writes that in a minyan where there is an excessive effort to get everyone back to shul for [[maariv]] (and people cannot wait in shul), it is permissible for a [[minyan]] to say [[maariv]] right after [[Mincha]] (between Plag [[Mincha]] and nighttime). Shulchan Aruch 233:1 says the minhag is like Rabbanan and Rama 233:1 says the minhag is like Rabbi Yehuda. Nowadays, Piskei Teshuvot 233:4 writes that the Ashkenazic minhag is also like Rabbanan. </ref> If the only ''minyan'' available is such a ''minyan,'' an individual should not join them for both ''mincha'' and ''maariv''.<ref>Mishna Brurah 235:14</ref> If one is needed to complete the ''minyan'' they may join.

===Maariv After Sunset Before Tzet===

#If one is ''davening'' with a ''minyan'' immediately after sunset one should ''daven'' with them completely and repeat ''shema'' after ''tzet''. Some have a practice to ''daven'' ''shema'' and ''shemoneh esrei'' together with the ''tzibbur'' while skipping ''birchot kriyat shema. Shema'' and the ''brachos'' are then repeated after tzet hakochavim.<ref>*The Rif (Brachot 1b) rules that the time to say [[Kriyat Shema]] at night is from [[Tzet HaKochavim]] like the simple Mishna and Gemara Brachot 2a. The Rambam (Kriyat Shema 1:9) concurs.
*Rashi (Brachot 2a s.v. Ad Sof) also holds that one does not fulfill Shema until [[Tzet HaKochavim]] but defends the practice to say Shema in Shul with the [[Brachot]] explaining that the Shema in Shul is only to precede [[Shmoneh Esrei]] with words of Torah, whereas the primary time one fulfills one's obligation of saying Shema is before going to sleep.
*Rabbenu Tam (quoted by Tosfot [[Brachot]] 2a s.v. Meeymatai) argues that really we hold like Rabbenu Yehuda in the Mishna (Brachot 26a) who says that one may say [[Arvit]] from Plag [[Mincha]], so too we hold that one may say Shema from Plag [[Mincha]]. The Ri (also quoted in the above Tosfot) agrees that the primary Shema is the one said in Shul, however, he explains that it is because we hold like the other opinions quoted in the Gemara 2a-b who say that the time for Shema is earlier than [[Tzet HaKochavim]].
*The Rosh (Brachot 1:1) rejects the Rabbenu Tam’s comparison between the time for [[Arvit]] and Shema and rather says that with difficulty one could defend the minhag like the Ri but nonetheless preferably one should say Shema only after [[Tzet HaKochavim]].
*The Rosh (Brachot 1:1) quotes the Rav Hai Goan who says that if one is in a situation where one could either pray with a [[minyan]] before [[Tzet HaKochavim]] or pray by oneself later one should pray with the [[minyan]] early but not say Shema with the [[Brachot]] until later. Rav Hai Goan also suggests that one could pray with the congregation as a voluntary [[prayer]] and then pray again oneself with Shema and [[Shmoneh Esrei]]. This is also quoted by the Rabbenu Yonah (Brachot 1b s.v. VeRabbenu Hai), Rashba (Brachot 2a s.v. VeNishal), and Tur 235:1.
*Rabbenu Yonah gives an alternative for someone in that situation; say [[Brachot]] of Shema, Shema with intent not to fulfill one’s obligation but rather just as words of Torah, and then [[Shmoneh Esrei]] with the [[minyan]] and after [[Tzet HaKochavim]] one should repeat Shema with the intent of fulfilling one's obligation.
*The Bet Yosef 235:1 concludes that one should make sure to repeat Shema after [[Tzet HaKochavim]] but one may follow the above suggestions (of Rav Hai and Rabbenu Yonah). Mishna Brurah 235:12 and Igrot Moshe 2:60 write that one can follow either Rav Hai or Rabbenu Yonah. The Shulchan Aruch 235:1 writes like the Rabbenu Yonah that if one is praying with a congregation earlier than [[Tzet HaKochavim]] one should say Shema with the [[Brachot]] and [[Shmoneh Esrei]] and then repeat Shema at [[Tzet HaKochavim]].
*The Mishna Brurah 235:9 writes like the Rabbenu Yonah that when saying Shema early one should not have intent to be fulfilling one’s obligation until [[Tzet HaKochavim]]. The Mishna Brurah 235:11 writes that it is a dispute whether one must repeat the third paragraph of Shema. Igrot Moshe 2:60 writes that one should repeat all three paragraphs.
*Igrot Moshe OC 2:60 explains that the reason that the Rabbenu Yonah and Mishna Brurah wrote not to have intent to fulfill one's obligation of kriyat Shema is because of a concern of [[Baal Tosif]]. If a person were to say Shema at the wrong time with intent that one should fulfill one's obligation it is like one is adding on to the time of the mitzvah similar to sleeping in the sukkah on the eighth day of sukkah with intent to add to sukkot (Rosh Hashana 28b). However, the Shulchan Aruch doesn't quote that it is necessary to have such an intent since the minhag is not to have intent to fulfill the mitzvah of Shema then (like Rashi Eruvin 96a s.v. v'od).</ref>
#If the only ''minyan'' for ''arvit'' is immediately after ''shekiya,'' one should ''daven'' with the ''minyan'' rather than ''davening'' later without a ''minyan''.<ref>Shulchan Aruch 235:1, Mishna Brurah 235:12. Rav Moshe Feinstein in Igrot Moshe OC 2:60 writes that in such a case one should certainly daven with a minyan and either the opinion of Rabbenu Yonah to daven Brachot Kriyat Shema with the congregation or Rav Hai Goan to skip them are acceptable. Biur Halacha 235:1 s.v. v'im quotes the Gra that it is better to wait for the proper time and ''daven'' alone. Igrot Moshe O.C. 2:60 writes that one should only follow this Gra if one always follows the Gra.</ref>

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===Latest Time===
#One should make sure to ''daven arvit'' before ''chatzot''. If one could either ''daven'' alone before ''chatzot'' or with a ''minyan'' after ''chatzot'' one should rather ''daven'' alone before ''chatzot''.<ref>Ishei Yisrael 28:15 based on Mishna Brurah 235:17 and quoting Rav Chaim Kanievsky, Or Letzion 2:15:9, Piskei Teshuvot 235:10. Piskei Teshuvot (235 fnt. 68) questions this since it is possible to recite kriyat shema before chatzot and then shemona esrei with the minyan after chatzot. [[Dating_Packet| Rav Hershel Schachter (cited in Halachos of Dating)]] holds that one should daven by oneself before chatzot rather than daven with a minyan after chatzot.</ref> Some disagree and allow ''davening'' with a ''minyan'' after ''chatzot,'' as long as one says ''shema'' before ''chatzot''.<ref>Halacha Brurah 235:20</ref>
#After the fact, one may pray [[Arvit|''arvit'']] all night until [[Olot HaShachar|''alot hashachar'']].<ref>Kitzur Shulchan Aruch 70:2</ref>
#One who had a predicament and was not able to ''daven'' at the proper time may recite ''shema'' up until ''netz hachama.''<ref>Shulchan Aruch O.C. 235:4</ref> He may recite ''birchos krias shema'' as well,<ref>Rama O.C. 235:4</ref> yet ''hashkiveinu'' and ''baruch Hashem l'olam'' are not recited after ''alot hashachar.''<ref>Shulchan Aruch O.C. 235:4, Mishna Brurah 235:34</ref> ''Shemoneh esrei'', as well, is not recited after ''alot hashachar.''<ref>Mishna Brurah 235:34</ref>

==Sources==
<references />
[[Category:Prayer]]