Reference of Measurements in Halacha

From Halachipedia

Kezayit

  1. According to Rav Chaim Noeh, the Kezayit for Deoritta measures (eating Matzah) and Bracha Achrona is 25.6 cc (in volume). Nonetheless because food stuck in between one's teeth doesn't count towards a Kezayit eaten one should make sure to have 28.8 cc. Regarding a Kezayit for derabbanan measures (eating maror) the kezayit is 17.3 cc. [1]

Kedi Achilat Pras

  1. According to Rav Chaim Noeh, the Kedi Achilat Pras is 4 minutes for measuring eatings for a mitzvah or bracha Achrona, however regarding a sick person eating in intervals on Yom Kippur the Kedi Achilat Pras should be measured as 9 minutes. [2]

Amah, Tefach, Etzbah

  1. According to Rav Moshe Feinstein, the Amah is 21.25 inches (53.98 centimeters), the Tefach is 3.54 inches (9.00 centimeters), and the Etzbah is 0.89 inches (2.25 centimeters). [3]
  2. According to Rav Chaim Noeh, the Amah is 18.90 inches (48 centimeters), the Tefach is 3.15 inches (8 centimeters), and the Etzbah is 0.79 inches (2 centimeters) [4]
  3. According to the Chazon Ish, the Amah is 24 inches (60.96 centimeters), the Tefach is 4 inches (10.16 centimeters), and the Etzbah is 1 inch (2.54 centimeters). [5]

References

  1. Shiurei Torah (by Rav Chaim Noeh, Siman 3 Seif 13 pg 191)
  2. Shiurei Torah (by Rav Chaim Noeh, Siman 3 Seif 15 pg 203)
  3. 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.
  4. Shiurei Torah (by Rav Chaim Noeh, Siman 3 Seif 25 pg 249)
  5. Shiurin shel Torah (pg 3) by the Steipler quoting the Chazon Ish but admitting that these are approximate measures because of the need to publicize the measures but not an accurate calculation.