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) 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>
# 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>
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>
==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 Torah (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 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. </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>
# 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 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>
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>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 Torah (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. == Kedi Shtiyat Reviyit== # See [[Kedi Shtiyat Reviyit]] (the time in which a [[Reviyit]] is considered drunk together) ==Prutah==
# 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 Torah (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 Shalom Alecha Rebbe. <ref>Kitzur Shulchan Aruch (Klalim s.v. Kedi)</ref> # [[Toch Kedi Dibbur]] is less than the time it takes to say Shalom Alecha Rebbe.<ref>Kitzur Shulchan Aruch (Klalim s.v. Kedi)</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. ==Shaot Zmaniot==
# [[Shaot Zmaniot]] are halachic hours which are calculated by dividing the daytime hours into 12. There’s a dispute of how to measure the day; some count the day from Olot HaShachar until [[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]] until [[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 Deoritta laws (including [[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 an 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>
# Many rishonim hold that [[Olot 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 degrees below the horizon for everywhere in the world, however, others hold that [[Olot HaShachar]] is 90 minutes on a perfect day which is 19.78 degrees below the horizon. <ref>
* 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 [[Olot HaShachar]] is 120 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 65-7) says that we assume that [[Olot 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 [[Olot HaShachar]] is assumed to be 72 minutes before sunrise, varying according to the longitude and latitude. </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-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>
* [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, in general, 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.
* [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>
# [[Chatzot]] is midday and midnight, always separated by 12 hours.<ref>Mishna Brurah 1:9 writes that [[chatzot]] at night is always 12 hours after [[chatzot]] of day for any place in the world.</ref>
# Mincha Gedola is six and a half halachic hours (Shaot Zmaniyot) after sunrise.<ref>Rashi (Pesachim 107a s.v. mincha gedola), Rambam (Tefillah 3:2)</ref>
# Mincha Ketana is nine and a half halachic hours (Shaot Zmaniyot) after sunrise.<ref>Rashi (Pesachim 107b s.v. oh), Rambam (Tefillah 3:2)</ref>
# [[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 locations. <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]] is the time period between certain daytime and certain nighttime. In many halachot, it is considered a doubt whether it is considered day or night and has many practical ramifications. There is a major dispute how long this period is. <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).]
# 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 can do no Melacha during [[Bein Hashemashot]] <ref> Mishnah [[Shabbos]] 34b </ref>.
==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)</reF>
* [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