There are many different [[measurements]] used in the
Toire 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.
# 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) discusses this at length. </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. Agav), Rambam (Eiruvin 1:9)). S”A 486 rules like Tosfot. Rav Avraham Chaim Noeh (Shiurei
Toire 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. </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) holds that the modern day eggs are half the size of those in the days of Chazal. However, Rav Noeh (Shiurei
Toire 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
Toire (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) Rav Chaim Kanievsky in Shiurin Shel Toire (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.]</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. </ref>
==Amah, Tefach, Etzbah==
# 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). <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. </ref>
# 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) <ref>Shiurei
Toire (by Rav Chaim Noeh, Siman 3 Seif 25 pg 249) </ref># 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). <ref> Shiurin shel Toire (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. </ref>
# When [[Mil]] is given in terms of time, some consider it 18 minutes, some 22.5 minutes, and some 24 minutes. <ref>Shulchan Aruch 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.</ref>
# 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>Shiurei Tzion (p. 69)</ref> the Chazon Ish holds that the [[Reviyit]] is 150 grams (5.3 oz).<ref> Rav Chaim Kanievsky in Shiurin Shel
Toire (p. 66) according to the rulings of the Chazon Ish </ref>, and some quote Rav Moshe as saying the [[Reviyit]] 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.
# See [[Kedi Shtiyat Reviyit]] (the time in which a [[Reviyit]] is considered drunk together)
# A [[prutah]] is 1/40 of a gram of silver (which is about a few cents). However, the [[prutah]] with regards to the mitzvah of returning a lost object is discussed [[Returning_Lost_Objects#Worth_a_Prutah| here]]. <ref> S”A CM 88:1 says a [[prutah]] is a half of a pearl of barley. Shiurei
Toire (Rav Chaim Noeh pg 177) and Shiurei HaMitzvot (Chazon Ish pg 65) say a [[prutah]] is 1/40 of a gram of silver (which currently is about 2.3 cents). 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>
==Toch Kedi Dibbur==
# [[Kedi Dibbur]] is the time it takes to say
Sholem Aleykhem Rebbe. <ref>Kitzur Shulchan Aruch (Klalim s.v. Kedi)</ref># [[Toch Kedi Dibbur]] is less than the time it takes to say Sholem Aleykhem Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedi)</ref>
# 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-
Toire 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.