Updated April 2022
Conscientious observance of kashrus goes beyond the identification of kosher symbols on your supermarket shelf and the separation of meat and dairy foods and utensils in your kitchen. There are many food related halachos, in addition to those involving preparation and serving. Amongst them are the halachos of shiurim, measurements. They encompass a wide range of issues relevant to food consumption, and have important halachic ramifications.
How much must one eat to recite a bracha acharona, the blessing after eating? How much bread must one eat to be obligated in netilas yadayim, hand washing, or to fulfill one’s obligation of seudas Shabbos? The answers to these and other questions relating to shiurim have been addressed by gedolei haposkim, but are often not well known. There are many age old opinions regarding shiurim and it is often difficult to translate the measurements of Chazal into today’s terms.
Additionally, though Chazal chose to describe measurements in terms of commonly used items or foods such as a kezayis (olive) and a kebeitza (egg), the size of a standard size egg 1800 years ago may have been larger than today’s egg. Similarly, there are many varieties of olives, and we are uncertain which one is used for the kezayis measure. Therefore, shiurim must be defined in contemporary terms. This article will attempt to clarify the halachic parameters of food related measurements.1
As with all halacha, for a definitive psak one must consult his Rav. The halachic rulings regarding shiurim by Rabbi Moshe Heinemann, shlit”a, Rabbinic Administrator of Star-K, are as follows:
I. Kezayis Measurement2 – 1.27 fl. oz. (38 ml) – If one eats a kezayis3 of bread, he must recite Birchas Hamazon.4 Similarly, if one eats a kezayis of any other food, a bracha acharona must be recited.
Our testing indicates that this is the approximate size of a golf ball (40 ml) or a roll of quarters (37 ml). A complete graham cracker (both halves) has a volume of approximately 27 ml. Therefore, if one eats only one graham cracker, a bracha acharona is not recited. An additional one half must be eaten in order to say the bracha acharona. A bracha rishona is required even for any amount less than a kezayis from which one is neheneh (derives benefit).
When eating bread or cake, one should calculate in his mind whether it has a volume of 38 ml (e.g. whether it has the volume of a golf ball). It is impossible to state how many slices of bread equal a kizayis, as bakeries and bread companies bake bread in many different sizes.
On the first two nights of Pesach one should eat two kezaysim of matzah at Motzi Matzah.5 This is equivalent to approximately one half of a standard size machine matzah or one half of an average hand matzah. If eating this amount is too difficult, one may eat one kezayis – i.e. one quarter of a machine matzah or one quarter of an average size hand matzah. A kezayis is also the amount of maror one must eat to fulfill that mitzvah.6
II. Kebeitza Measurement – 2 kezaysim, 2.53 fl. oz. (75 ml) – The kebeitza7 measurement is relevant to numerous halachos throughout the year. It is equivalent to approximately two golf balls. When washing before eating bread, one recites the bracha of Al Netilas Yadayim only if one intends to eat a kebeitza of bread.8
It is preferable for one to eat more than a kebeitza of bread at each of the three Shabbos meals and two Yom Tov meals. Similarly, on the first two nights of Sukkos, ideally one should eat this amount of bread9 in the sukkah.10 During the rest of Sukkos, if one eats more than a kebeitza of bread or cake, a bracha of Leishev Basukkah is recited.
III. Kedei Achilas Pras Time Measurement – Volume is not the only factor in determining whether a bracha acharona is recited. Chazal dictate that a bracha acharona is only recited if one eats a kezayis in the amount of time known as kedei achilas pras.11 This means, to recite a bracha acharona, one should eat a kezayis ideally within two minutes (see footnote.).12 For example, if one eats bread, one should consume a kezayis within any two minute span during the meal to recite Birchas Hamazon.13
To fulfill mitzvos requiring a kezayis the food must be eaten within the kedei achilas pras time period. For example, on the first two nights of Pesach one should eat a kezayis of matzah within a two minute period.
IV. Revi’is – The ‘classic’ measurement of liquids is a revi’is.14 The Chofetz Chaim15 was of the opinion that this is 3.8 fl. oz. (112 ml). In order to recite a bracha acharona on any beverage, one must drink a revi’is.16 Similarly, the cups used for Kiddush, Havdalah and at the Seder on Pesach night for the four kosos, must hold a revi’is.
The standard measurement of a cup (as found in recipes or on measuring cups) is 8 fl. oz. Therefore, a revi’is is approximately one half of a cup. Four plastic schnapps cups that state on the bottom “1 fl. oz. – 29 ml” are also approximately a revi’is. As a point of reference, a can of soda is 12 oz. – slightly more than three times the revi’is measure.
Although a Kiddush cup must hold a revi’is, the amount of wine that one who recites Kiddush needs to drink is a meloh lugmav, one cheekful.17 This amount is different for each person. In general, a meloh lugmav for adults ranges between 1.55 fl. oz. and 2 fl. oz. The way each person calculates his own meloh lugmav will be addressed in section VI-B.
Similarly, a meloh lugmav must be drunk for Havdalah. At the Pesach Seder, for each of the four cups one must drink at least a rov revi’is (2 fl. oz.) or a meloh lugmav – whichever is larger.18
V. Halachic Time Frame When Drinking Beverages – As with eating, Chazal dictate that a bracha acharona is only recited if one drinks a revi’is within a stipulated amount of time. Unlike food where this time is kedei achilas pras, the “time limit” for beverages is “kedei shti’as revi’is.”19 This means that to recite a bracha acharona on wine or any other beverage, one must drink 3.8 fl. oz. within a thirty second span.20
It is difficult to drink a hot beverage such as coffee within the thirty second time span, as hot drinks are generally sipped slowly. If 3.8 fl. oz. are not consumed during any thirty second span, a bracha acharona is not recited. The same applies to hot soup. Although a hot beverage is initially too hot to drink in the halachic time limit for drinking, eventually, if it cools and 3.8 fl. oz. are drunk within 30 seconds, a bracha acharona is required.21
VI. Cholim – Shiurim For One Who Is Ill On Yom Kippur
A. Food – Someone whose life may be in danger by fasting on Yom Kippur is obligated to eat. Not all cholim who are obligated to eat on Yom Kippur have the same halachic dispensation. There are cholim (who may be in danger) whose illness only warrants minimal eating or drinking. Minimal consumption is termed pachos mi’keshiur – below the minimal portion that qualifies for halachic22 eating and/or drinking. What is pachos mi’keshiur for eating and drinking? On Yom Kippur the pachos mi’keshiur requirement is the volume of food that is less than a koseves hagasa, a type of large date. The volumetric measurement of a koseves hagasa23 is more than 1.5 fl. oz. (44 ml). Therefore, one who is ill (as above) may eat 1.5 fl. oz. (which is less than a koseves hagasa) of food every nine minutes. A practical way for the patient to do this is as follows: Fill 11/2 schnapps cups that are marked ‘1 oz. – 29 ml’ with compacted24 bread, crackers or cereal, and consume that amount every nine minutes. If waiting nine minutes still poses a danger, one may eat every four minutes, etc.
Note: If it is determined that this amount is insufficient and one’s life may still be in danger, the patient must eat as much as necessary, even if it is more than the shiur of volume and less time than kedei achilas pras.
B. Beverages on Yom Kippur – The minimal volume for beverages that qualifies for pachos mi’keshiur (minimal consumption by a choleh whose life may be in danger) is less than a meloh lugmav, a cheekful of liquid. Unlike food, the shiur of liquids differs with each individual’s capacity to hold liquid in his or her mouth. The larger the mouth, the larger the meloh lugmav. Conversely, the smaller the mouth, the smaller the meloh lugmav. For purposes of drinking on Yom Kippur we say an average adult has a meloh lugmav25 that is larger than 1.5 fl. oz. (44 ml). A teenager may have a smaller meloh lugmav. One can ascertain his or her personal meloh lugmav by filling his mouth completely with water, expelling the water into a measuring cup and dividing the amount in half.26 This number is the amount held by one cheek – a meloh lugmav.27 Pachos mi’keshiur is slightly less than this amount. This “test” should preferably be conducted before Yom Kippur.
How infrequently should a person who is forced to drink on Yom Kippur take a drink so that his intake does not qualify for halachic drinking?28 Ideally, less than a meloh lugmav may be consumed and then repeated up to every seven minutes. If this amount of liquid is insufficient for the patient, one may drink this amount of liquid every two minutes.
Note: If it is determined that this amount is insufficient and one’s life may still be in danger, the patient must drink as much as necessary, even if it is more than the shiur of volume and less than the shiur of time.
On Yom Kippur, the pachos mi’keshiur amounts of food and drink are independent of each other. This means the two shiurim do not combine and one can simultaneously eat and drink a pachos mi’keshiur of both. The waiting times are also calculated independently.29
If one must eat on Yom Kippur, the following sample schedule of eating pachos mi’keshiur may be implemented: Eat and drink at 8:00 a.m., drink – 8:07, eat – 8:09, drink – 8:14, eat – 8:18, drink – 8:21, eat – 8:27, drink – 8:28, drink – 8:35, eat – 8:36, etc. This schedule is for someone who wishes to eat as much as possible pachos mi’keshiur30 in the shortest amount of time. Obviously, a choleh may eat and/or drink pachos mi’keshiur less frequently (e.g. eat and drink pachos mi’keshiur at 8:00 a.m., then eat and drink again pachos mi’keshiur at 8:15 a.m., etc.). If possible, the decision whether one may eat or must eat – pachos mi’keshiur or more than the shiur – should be discussed with a competent halachic authority before Yom Kippur.
VII. Hafrashas Challah – Min haTorah, the amount of flour one must knead to be obligated in hafrashas Challah is an “asiris ha’aifa.” This is equivalent to the volume of 431/5 eggs.31 Regarding hafrashas Challah, the exact volume of this shiur is in doubt.32 L’halacha, one should be mafrish Challah when kneading 2.6 lbs. of flour, which on average is equivalent to 82/3 cups of flour.33 However, a bracha is not recited for this amount. If one kneads a smaller amount of flour, one is not mafrish Challah.34
There are two customs as to the amount that must be kneaded to require a bracha. Some individuals recite a bracha when kneading 3.675 lbs. or more of flour (on average, 121/4 cups).35 Many only recite a bracha when kneading 4.95 lbs. of flour (i.e. almost the entire contents of a 5 lb. bag of flour – on average, 161/2 cups of flour).36 Individuals should follow their family custom.37
Whether we are gathered at the Shabbos table, celebrating and preparing for our beautiful Yamim Tovim, or just enjoying a midnight snack, shiurim play a vital role. By understanding and knowing them, we can measure up to the task of fulfilling these mitzvos l’shem u’ltiferes.
The author wishes to thank Dr. Yossi Scheller and Mrs. Paysach Freedman for their assistance in the preparation of this article.
1. Note: It is important to emphasize that shiurim are measured in terms of volume, not weight. For example, a kezayis of sponge cake will volumetrically equal a kezayis of potato kugel, yet the weight of the potato kugel will exceed the weight of the sponge cake.
2. For an explanation as to how this measurement is derived, see footnote 26.
3. Literally, “like [the size of] an olive.”
4. Shulchan Aruch, Orach Chaim (henceforth all references to Shulchan Aruch refer to Orach Chaim) 184:6
5. Shulchan Aruch 475:1. For a detailed discussion of the various opinions regarding shiurim at the Pesach Seder, see HERE.
6. A kezayis is also a commonly used shiur with regard to ‘onshin.’ In the days of the Sanhedrin if, after being warned, one ate a kezayis of non-kosher food, or milk and meat that was cooked together, he was chayav malkos. Eating less than a kezayis (known as chatzi shiur) is also prohibited min haTorah (but there is no onesh in Beis Din).
7. Literally, “like [the size of] an egg” – also pronounced k’baya. For an explanation as to how this number is derived, see footnote 26.
8. Shulchan Aruch 158:2. One washes without reciting Al Netilas Yadayim when eating any amount, even if it is less than a kezayis (see Mishna Berurah 158:10).
9. Mishna Berurah (henceforth abbreviated MB) 291:2. Bedi’eved, a kezayis is enough.
10. MB 639:22. Bedi’eved, a kezayis is enough (Shulchan Aruch 639:3). If it is raining, one should eat a kezayis without reciting Layshev B’sukkah (MB 639:35).
11. MB 210:1. This means the amount of time it takes to eat three or four eggs.
12. See Teshuvos Chasam Sofer 6:23. It should be noted that the two minutes are measured from the time the first part of the kezayis is swallowed until the last part of the kezayis is swallowed. Bedi’eved, if one eats a kezayis within four minutes, a bracha acharona may be recited (see Aruch Hashulchan 202:8 and Shmiras Shabbos K’Hilchasa 48:10).
13. It is a hiddur to eat a complete kezayis of bread immediately after reciting Hamotzi (MB 167:15).
14. Literally, this means one fourth [of a lug – an ancient measurement].
15. See Biur Halacha 271:13 (s.v. shel revi’is) who says a kiddush cup must hold the volume of two eggs in their shells. Nowadays, eggs have a volume of 1.9 fl. oz. (56 ml) – hence a revi’is is 3.8 fl. oz. (112 ml).
16. Shulchan Aruch 190:3. There are opinions that hold a bracha acharona is recited when drinking the volume of a kezayis (1.27 fl. oz. – 38 ml). Although we do not hold like these opinions and only recite a bracha acharona when drinking a revi’is, nonetheless, to avoid a safek bracha acharona, it is generally recommended not to drink between 1.27 fl. oz. and 3.8 fl. oz. (i.e., do not consume the amount between a kezayis and a revi’is).
17. Only the one who recites Kiddush needs to drink. Those being yotzei Kiddush need not drink the wine, however, many have the custom to do so. If the mekadesh is unable to drink the full meloh lugmav, others may drink it – and all are yotzei if their ‘collective drinking’ adds up to the average meloh lugmav.
18. See Shulchan Aruch 472:9 and Mishna Berurah. Some are stringent for the four cups on Pesach to drink a ‘rov kos‘ – at least 51% of the contents of the cup – if it is larger than a meloh lugmav and rov revi’is. For the fourth cup one should drink a revi’is so that a bracha acharona can be recited. Alternatively, if one drinks only a meloh lugmav, someone who drank a revi’is should be motzi you.
19. MB 210:1. It should be noted that there are opinions that hold the shiur for beverages is kedei achilas pras. See Shulchan Aruch 612:10 and MB 612:31.
20. Shiur shti’as revi’is is based on the amount of time it takes most people to drink b’shtei pe’amim (the proper way to drink as discussed in Shulchan Aruch 170:8; see Shaar Hatzion 210:11). This time is 30 seconds.
21. Regarding ice cream, ices and gel desserts, the poskim question whether they are foods or beverages. The custom is to consider them as foods. For a full discussion see Sefer V’zos Habracha, Chap. 5.
22. The halachos regarding the shiurim (amount and time) of Yom Kippur are addressed in Shulchan Aruch 618:7 and 8 and Mishna Berurah, as well as Shmiras Shabbos K’Hilchasa 40:18-27. It should be noted that eating (or drinking) pachos mi’keshiur is still prohibited for a healthy person (chatzi shiur assur min haTorah), however, there is no onesh kares or malkos from Beis Din.
23. A koseves hagasa is “slightly less than a k’baya” (Shulchan Aruch 612:1). Nowadays, an egg is 1.9 fl. oz., and therefore, for Yom Kippur, the size of a koseves hagasa must be less than this amount. Also, it is customary to use the strictest opinion regarding kedei achilas pras (9 minutes). If one requires more food or must eat in shorter spans, a rav should be consulted, as there are more lenient opinions.
24. As previously indicated, shiurim are measured in terms of volume, not weight. Therefore, to obtain the most amount of food that is still pachos mi’keshiur, it is advisable to compress the food as much as possible (e.g., stuff bread into a shnaps cup) before eating.
25. For Yom Kippur, we are machmir to use the lower range of the average for meloh lugmav.
26.Tosfos (Yuma 80a s.v. Hachi) says the amount one can fill his entire mouth (both cheeks) is greater than a revi’is. Hence a meloh lugmav (one cheekful) is often referred to as rov revi’is. This fact is the basis of calculating the volume of a kezayis. If a revi’is is less than two cheekfuls, and two cheekfuls equal two eggs (available nowadays – see Biur Halacha cited in footnote 15), and one egg nowadays has a volume of 1.9 fl. oz., this means a revi’is must be less than 3.8 fl. oz. A revi’is equals 1.5 beitzim (at the time of Chazal). This means 1.5 beitzim are less than 3.8 fl. oz., one beitzah is less than 2.53 fl. oz., and one kezayis (half of a kebeitzah) is less than 1.27 fl. oz. (38 ml). Therefore, if one eats food with a volume of 1.27 fl. oz. (38 ml), he has certainly eaten a kezayis and may therefore recite a bracha acharona. This method can also be used to determine how much of Kiddush one must drink.
27. This method can also be used to determine how much of Kiddush one must drink.
28. See footnote 22.
29. If one dissolves sugar into water (or another beverage), the sugar is no longer considered a food, but rather a beverage. Therefore, one may eat granulated sugar or candy that is less than a koseves hagasa, and then immediately drink ‘sugar water’ (with dissolved sugar) that is less than a meloh lugmav. The sugar/candy and the dissolved sugar do not combine to add up to a shiur (i.e. they are not mitztaref). This ‘solution’ is advisable for one who requires an immediate intake of sugar.
30. See end of footnote 23.
31. There are six eggs in a lug – 24 lugen in a se’ah – three se’ah in an aifa, so there are 432 eggs in an aifa – a tenth of this (an asiris ha’aifa) is 43.2 or 431/5 eggs.
32. A full discussion of the different sizes of eggs for different halachos is beyond the scope of this article.
33. An 8 oz. cup of flour generally weighs between 4.2 and 5.3 oz. There is no precise conversion between the weight and volume of flour. The temperature, methods of storage, type of flour, how one fills the measuring cup, and whether it is sifted, can all impact on this amount. We use the following calculations (based on our testing and observations): The average weight of one cup of flour is 4.8 oz., which also means 1 lb. of flour will fill 31/3 cups.
34. One should not intentionally minimize the amount of flour in order to exempt oneself.
35. Based on the opinion of HaRav Avraham Chaim Naeh, in his Sefer Shiurei Torah.
36. Based on the opinion of the Chazon Ish.
37. These halachos apply when baking bread or any other Hamotzi product. When kneading dough for other products and for a full discussion of the halachos of hafrashas challah, see the Kashrus Kurrents article, “When You Need to Knead: A Guide to Hafrashas Challah” by clicking HERE.