Chapter 22: The Shiurim – Kezayis, Revius, Achilas Peras

This chapter will focus on a full detailed analysis on one of the most complex and debated subjects in Jewish law and that is the definition of the Shiurim brought in the Torah, such as Kezayis, Revius and Achilas Peras. In the previous chapter, we mentioned that the after blessing may only be recited if one consumed a Kezayis of food or Revius of beverage within Achilas Peras. What exactly does this mean and what are its exact measurements? The relevance of the subject is not limited to the laws of blessings, but extends to many different Mitzvahs.

1. How much is a Kezayis?[1]

Regarding saying an after blessings such as Meiyn Shalosh, Borei Nefashos and Birchas Hamazon, after consuming a Kezayis of food/bread, one is not to say an after blessing until he eats 28.8 grams of the food within Achilas Peras. Likewise, initially one is to beware not to enter himself into a doubt of a Safek Bracha, and he is thus not to consume more than 17.3 grams but less than 28.8 grams. Below is a full analysis on the subject and how we reached our conclusion.

1. Background and theoretical size in Talmudic terminologies:[2]

The type of olive referred to in the term Kezayis:[3] The Kezayis which is mentioned in all Halachic literature refers to a medium and average size olive, which is not large or small. This sized olive is called an Agguri olive in Hebrew, as its oil is gathered within it.

Its size in comparison to eggs:[4] The exact measurement of the above-mentioned olive is traditionally ratioed versus the size of an egg. However, it is disputed amongst the Poskim as to the exact ratio that the above-mentioned olive has versus the measurement of an egg.[5] Some Poskim[6] rule that it has the ratio of approximately one half of an egg [without its peel[7]]. Other Poskim[8] rule that it has the ratio of slightly less than one third of an egg [with its peel[9]]. Practically, by Rabbinical commands one may be lenient, while by Biblical commands one is to be stringent, as will now be explained.[10] [Nonetheless, some Poskim[11] rule that even by Rabbinical command one is initially to be stringent. This especially applies by commands, over which a blessing is recited.[12] One who is sick and cannot eat the larger Kezayis amount may even initially be lenient and eat the lesser Kezayis amount.[13]]

The law by an after blessing:[14] Regarding saying an after blessings such as Meiyn Shalosh, Borei Nefashos and Birchas Hamazon, after consuming a Kezayis of food/bread, one is to be stringent to not say an after blessing until he eats the measurement equal to half of an egg.[15] Likewise, initially one is to beware not to enter himself into a doubt of a Safek Bracha, and he is thus not to consume the above questionable amount[16], and is either to eat approximately a measurement equal to half of an egg, or much less than one third of an egg, by all foods that one is not required to eat a Kezayis of them.

The law by other cases of Kezayis: See our corresponding Sefer the laws and customs of the Pesach Seder for the application of this subject to the Shiur for Matzah, Maror, and other foods of the Seder night.

1. How much is a Kezayis-Translating the Kebeitza and Kezayis into grams/volume:

Above it was determined that there exist two theoretical sizes of a Kezayis, one being 1/3 of an egg and the second being ½ of an egg, and that by Biblical commands we use the stringent measurement while by Rabbinical commands one may use the lenient measurement. The difficulty in practically determining the exact amount of gram or volume measurements that this translates into is twofold: 1) It requires one to determine the volume/weight of an egg, for which the 1/3 or ½ Kezayis ratio can then be derived from. Indeed, the practical volume/weight of an egg is debated amongst the Poskim, as will be explained. 2) Another issue present is regarding the form of measurement, whether we measure versus the weight of an egg/Kezayis or versus its volume size. If we measure versus the volume size, then even a food which is lighter than an egg/olive will still contain an equal volume size in determining its Kezayis measurement. Likewise, even a food which is heavier than an egg or olive, will still contain an equal volume in determining its Kezayis measurement. However, if we follow the weight, then a food which is lighter than an egg/olive will require a greater volume. Likewise, a food which is heavier than an egg or olive, will require a smaller volume. Thus, the determination of whether we follow the weight or volume of the gg/olive is crucial for determining the exact amount of a Kezayis. We will now address both of these issues, beginning with the second issue of volume versus weight.

Following volume not weight:[17] All the Torah measurements are measured in volume and not weight. [Nevertheless, due to the difficulty in determining the volume of an item, therefore for simplicity purposes, we practically measure in weight.[18] Nonetheless, this weight must be commensurate to its Halachic Kezayis volume. Thus, a food which is lighter than water [of which its weight and volume is equal], and thus floats on it, will require a lesser weight in its Kezayis then a Kezayis of water. For example, if a Kezayis equals 26cc, which is equal to 26 grams of water, then a food which floats on water will need less than 26 grams for its Kezayis, and within less than 26 grams of weight it already contains a volume of 26cc. On the other hand, a food which weighs more than water, and hence sinks in it, will require a greater weight in its Kezayis, and thus will need more than 26 grams for it to attain its 26cc.[19]]  

What is the volume/weight of a Kebeitza: There exists a major debate amongst the Poskim[20] in regards to the volume size of the Kebeitza, which in turn has created a consequential debate regarding the volume size of a Kezayis. Some Poskim[21] rule that the Kebeitza egg referred to by the Talmud was of a larger size than we have available today, and hence its volume is 100cc. This approach is formally known as Shiur Chazon Ish. Other Poskim[22], however, rule that no change has occurred within the egg sizes from the times of the Talmud, and hence the volume of an egg [without its peel[23]] equals 54cc. This approach is formally known as Shiur Avraham Chaim Naah. Practically, the widespread custom of world Jewry, Ashkenazim and Sephardim, is like the latter approach, and hence a Kebeitza is measured as 54cc.[24] This is equal to 54 grams of water, and hence for simplicity purposes, rather than measuring the volume of the food to make sure it contains 54cc one can simply weigh it to see that it contains 54 grams [unless the food weighs more than water in which case its Kebeitza weight would be more than 54 grams, while if it weighs less than water, then its Kebeitza weight would be less than 54 grams, as explained above]. Nonetheless, there are some Jews of Lithuanian Jewry who are stringent like the former approach and measure the Kebeitza as 100cc/grams. This especially applies by a Biblical Mitzvah.[25] We will now discuss the practical volume/weight of a Kezayis.

What is the volume and weight of a Kezayis: Above it was determined that the volume of a Kebeitza is 52cc, which is equal to 52 grams of water, and that the size of a Kezayis is measured as ½ of a Kebeitza regarding all Biblical Mitzvos, and as 1/3 of a Kibeitza regarding all Rabbinical Mitzvos. Thus, practically, the size of a Rabbinical Kezayis is 17.3cc, which is equal to 17.3 grams of water, while the size of a Biblical Kezayis is 26cc grams [lit. 25.6cc], which is equal to 26 grams of water.[26] Thus, for simplicity purposes, rather than measuring the volume of the food to make sure it contains 17 or 26cc one can simply weigh it to see that it contains 17 or 26 grams [unless the food weighs more than water in which case its Kezayis weight would be more than 17/26 grams, while if it weighs less than water, then its Kezayis weight would be less than 17/26 grams, as explained above], and so is the custom.[27]

Eating a slightly larger volume/weight than the technical Kezayis/Kebeitza size:[28] In all cases that one is required to eat a minimum measurement of Kezayis or Kebeitza one is to eat slightly more than the exact Shiur, as the food that gets stuck in the teeth and is not swallowed does not count towards it.

1. How much is a Kezayis-The practical size in grams/volume:

The law by an after blessing: Regarding saying an after blessings such as Meiyn Shalosh, Borei Nefashos and Birchas Hamazon, after consuming a Kezayis of food/bread, one is to be stringent to not say an after blessing until he eats 28.8 grams of the food. Likewise, initially one is to beware not to enter himself into a doubt of a Safek Bracha, and he is thus not to consume more than 17.3 grams but less than 28.8 grams.

• If already ate between 17-28 grams:[29] If one ate 17 grams of seven species fruit then if he already ate a Kezayis of Mezonos, then one should include an Al Hapeiros in Meiyn Gimel due to the doubt.

The law by other cases of Kezayis: See our corresponding Sefer the laws and customs of the Pesach Seder for the application of this subject to the Shiur for Matzah, Maror, and other foods of the Seder night.

2. How much is a Revius?[30]

The measurement of a Revius refers to a Revius of a Lug[31], which is equivalent to the volume of one and a half eggs with its shell.

The original Halachic measurement in dimensions of a cup:[32] The measurement of a Revius by a completely square cup is two fingers [i.e. 2×2 Etzbaos] in width and length and 2.7 fingers in height. The measurement of a Revius by a round cup is two fingers in width and length and 3.6 fingers in height.

The practical measurement in volume CC: Practically, there is a dispute amongst the Poskim[33] regarding the length of this “finger” measurement, which consequently created a dispute regarding the exact amount in fluid measurements that a Revius contains:[34] Some Poskim[35] rule that a Revius is equivalent to 86.4 milliliters or 2.92 fluid ounces. This measurement is the same Gematria as the word כוס. This opinion is known as Shiur Rav Chaim Neah. Other Poskim[36] rule it is equivalent to 81 milliliters or 2.73 fluid ounces. Other Poskim[37] rule it is equivalent to 84 milliliters or 2.84 fluid ounces. Other Poskim[38] rule that it is equivalent to 99 milliliters or 3.34 fluid ounces. Other Poskim[39] rule that it is equivalent to 108.8 milliliters or 3.67 fluid ounces. Other Poskim[40] rule that it is equivalent to 115.2 milliliters or 3.89 fluid ounces. Other Poskim[41] rule that it is equivalent to 118 milliliters or 3.99 fluid ounces. Other Poskim[42] rule that it is equivalent to 120 milliliters or 4.05 fluid ounces. Other Poskim[43] rule that it is equivalent to 123 milliliters or 4.16 fluid ounces. Other Poskim[44] rule that it is equivalent to 150 milliliters or 5.07 fluid ounces [Gematria of כוס הגון]. This is known as Shiur Chazon Ish. Other Poskim[45] rule that it is equivalent to 168 milliliters or 5.68 fluid ounces. Practically, the widespread custom of the world, Sephardim, Chassidim, and Ashkenazim, follows the first opinion above, for the cup to suffice to contain a minimum of 86 milliliters which is the same Gematria as the word Kos.[46] This applies whether Lechumra or Lekula [to be stringent or lenient], including even for Safek Brachos. However, there are some members of Lithuanian Jewry who are initially stringent like the Shiur Chazon Ish of 150 milliliters.[47] Likewise, some in Chabad are initially stringent like some of the other opinions mentioned.]

Areas in Halacha that a Revius is relevant:

In Halacha, the measurement of a Revius is relevant for various Halachos including:

• After blessing:[48] One must consume a Revius of liquid [within a certain amount of time[49]] in order to be able to say an after blessing.
• The size Kiddush cup to buy or use for Kiddush, Havdalah, Four cups of Pesach, Kos Shel Bracha:[50] One must use a cup that holds a Revius of wine or other valid beverage in order to be Yotzei Kiddush, Havdalah, or other Kos Shel Bracha.
• The amount to drink by the four cups on Pesach:[51] Although during Kiddush of Shabbos and all Yomim Tovim one is not required to drink majority of the Kiddush cup so long as he drinks the measurement of Malei Lugmav[52], nevertheless, by the four cups of the night of the Seder one is to initially drink the entire cup of wine.
• Kiddush Bemakom Seuda:[53] One who drinks a Revius of wine after saying Kiddush is considered to have fulfilled Kiddush Bimakom Seuda.
• Simcha on Yom Tov:[54] Some say that men must drink at least a Revius of wine on Yom Tov and Chol Hamoed in order to be Yotzei the Mitzvah of Simcha.
• Tasting food:[55] One who tastes a Revius of a drink is to say a before blessing even if plans on spitting it out.
• The morning Netilas Yadayim:[56] The vessel used to pour the water must contain at least a Revius worth of water prior to beginning the first pouring. [If it does not contain a Revius worth of water, the washing is invalid.[57]] [If one spills a Revius of clean water into the impure water of the morning washing, one may learn Torah in its presence.[58]]
• Netilas Yadayim for bread:[59] The vessel used to pour the water must contain at least a Revius worth of water prior to beginning the first pouring, otherwise the washing is invalid.
• Nullifying urine:[60] If one pours a Revius of water into urine, the urine is considered nullified and one may learn Torah and Daven near it.
• Davening after drinking wine:[61] One who drinks a Revius of wine or alcohol, has certain limitations regarding Davening.
• Avoda Bamikdash and Nesias Kapayim:[62] One who drinks a Revius of wine or alcohol, may not serve in the Temple. Likewise, a Kohen may not perform Nesias Kapayim if he drank a Revius of wine.
• Zimun:[63] One who drinks a Revius of liquid can join others for a Zimun.

3. How much is Kdei Achilas Peras?

Regarding an after blessing, we will conclude that Kdei Achilas Peras is 3-4 minutes and hence one is to eat a Kezayis of food within 3 minutes, and at the very least within four minutes, to say an after blessing. The following is the background on this subject.

1. The theoretical measurement in bread eating:[64]

Kdei Achilas Peras is the amount of time it takes to eat a half a loaf of bread. This refers to bread made of wheat.[65] The amount to time it takes to eat a Peras of this bread refers to when it is eaten quickly.[66] It likewise refers to when it is eaten in a state of reclining and is eaten together with a dip.[67] It is eaten without him moving around here and there [which would cause a delay in his eating], and is eaten quickly.[68] 

The debate: Now, it is disputed amongst the Poskim as to the volume contained within this loaf. This dispute relates to all Torah prohibitions, whether Biblical or Rabbinical.[69] Some Poskim[70] rule it refers to a wheat loaf which contains the volume of six eggs, and thus Kdei Achials Peras is the amount of time it takes to eat three Kibeitza’s [i.e. egg volume worth] of bread. Other Poskim[71] rule this refers to a loaf which contains the volume of eight eggs, and thus Kdei Achials Peras is the amount of time it takes to eat four Kibeitza’s [i.e. egg volume worth] of bread. Practically, regarding all Biblical matters one is to be stringent like the more stringent opinion, while regarding all Rabbinical matters one may be lenient like the more lenient opinion.[72]

The Shiur by an after blessing:[73] Regarding an after blessing, one is to be stringent like the more stringent opinion and hence to be able to say an after blessing one must consume the food within three Kebeitza worth of eating.

The Shiur for Yom Kippur:[74] Regarding the eating Shiurim for a dangerously ill person on Yom Kippur we hold that Kdei Achilas Peras is four Kibeitza’s worth of bread eating.

The Shiur by Matzah of Motzi Matzah:[75] Regarding the eating of Matzah to fulfill the Biblical Mitzvah, we rule that Kdei Achilas Peras is three Kibeitza’s worth of bread eating. Thus, one must consume the Kezayis of Matzah within three Kebeitza worth of eating. 

The Shiur by Matzah of Koreich and Afikoman, and for Maror:[76] Regarding the eating of Matzah and Maror to fulfill the Rabbinical Mitzvah of Maror, Koreich and Afikoman, we rule that Kdei Achilas Peras is four Kibeitza’s worth of bread eating. Thus, one must consume the Matzah within three Kebeitza worth of eating. 

1. The practical time in minutes:[77]

The debate: There are various opinions regarding the number of minutes it takes to eat 3 or 4 Kebeitza’s of bread, and hence the practical time of Kdei Achilas Peras is under debate. The following are the various opinions in the Poskim: Some Poskim[78] rule that Kdei Achilas Peras is 2 minutes. Other Poskim[79] rule that Kdei Achilas Peras is 3 minutes. Some Poskim[80] rule that Kdei Achilas Peras is 4 minutes. Some Poskim[81] rule that the Shiur of Kdei Achilas Peras is 6-8 minutes. Some Poskim[82] rule that the Shiur of Kdei Achilas Peras is 9 minutes.

The Shiur by an after blessing:[83] Practically, one is to eat a Kezayis of food within 3 minutes, and at the very least within four minutes, to say an after blessing. [Nevertheless, if one ate 17 grams in the first 4 minutes and completed 28 grams in 8 minutes then he may recite a Bracha Achrona.[84]]

The Shiur for Yom Kippur:[85] One who is required to eat or drink according to Shiurim on Yom Kippur is to initially consider Kdei Achilas Peras as nine minutes.

The Shiur by Matzah for Motzi Matzah:[86] Practically, one is to eat the Biblical Kezayis of Matzah within 3 minutes, and at the very least within four minutes.

The Shiur by Matzah for Koreich, and Afikoman:[87] One is to eat the Kezayis of Matzah within 5 minutes, and at the very least within nine minutes. Nonetheless, initially it is best to eat the food within 3-4 minutes, as ruled above regarding the Biblical Kezayis. [88]

The Shiur by Maror for Maror and Koreich:[89] One is to eat the Kezayis of Maror within 5 minutes, and at the very least within nine minutes. Nonetheless, initially it is best to eat the food within 3-4 minutes, as ruled above regarding the Biblical Kezayis of Matzah. [90]

The four cups: Initially one is to drink the entire cup of wine, or at the very least majority of the cup of wine, in one shot. Bedieved, one fulfills his obligation if he drinks Malei Lugmav within 3-4 minutes, and at the very least within nine minutes.

Child, sick or old:[91] A child, or one who is sick or old and has difficulty eating the Matzah/Maror within the above time, may be lenient to eat it within nine minutes. If one cannot do so even within nine minutes, then a blessing is not to be recited prior.

[1] See Admur 486:1-2; Kaf Hachaim 486:1-3; Ketzos Hashulchan 59 footnote 1; Piskeiy Teshuvos 486:1-3

[2] Admur 486:1-2

[3] Admur 486:1; Rambam Machalos Assuros 14a; Brachos 39a; Mishneh Keilim 17:8

[4] Admur 486:1; See Tzemach Tzedek 69 and 209; Shiureiy Torah p. 129 and 193; Yechaveh Daas 1:16

[5] The source of this dispute is based on a similar dispute in the laws of Eiruvin, with regards to how much is the amount of “two meals” that one needs to place for Eiruv Chatzeiros, as will be explained in the footnotes below

[6] 1^st opinion in Admur ibid and 2^nd opinion in Admur 368:3; Michaber 486:1 in name of Yeish Omrim and 2^nd opinion in Michaber 368:3; Darkei Moshe 475:1; Terumas Hadeshen 139; Drashos Maharil Seder Haggadah p. 11; Maryu 123; Tosafus Eiruvin 80b; Yuma 80a; Chulin 103b; Piskei Tosafus Chulin 272; Mordechai Perek Arvei Pesachim Seder Shel Pesach 38; Rashi Eiruvin 4a; Tur 409; Pesakim Ukesavim 26

The source from Eiruv Chatzeiros: The measurement of two meals for Eiruv Chatzeiros is 18 Gerogeros. [Admur 368:3; Michaber 368:1; Rav Yehuda in name of Shmuel Eiruvin 81b] Now, some Poskim rule that this amount calculates to 8 eggs, [2^nd opinion in Michaber 368:3 and Admur 368:3; Rashi Eiruvin 4a; Tur 409] or slightly more than 18 half eggs [Admur 486:1; Tosafus Eiruvin and Yuma ibid; See Bach 409] This proves that according to these Poskim, a Gerogeres is 1:2 of an egg. Now, being that an olive is a smaller measurement than a Gerogeres [See Shabbos 91a], therefore we can conclude that a Kezayis is less than even 1:3 of an egg. [See Admur ibid]

[7] Shiureiy Torah 3:12; Chazon Ish 39:17

Other opinions: Some Poskim rule that the half Beitza is measured with its peel. [M”B 486]

[8] 2^nd opinion in Admur ibid and 1^st opinion in Admur 368:3; 1^st opinion in Michaber 368:3; Rambam Eiruvin 1:9 as learns Peri Chadash

The source from Eiruv Chatzeiros: The measurement of two meals for Eiruv Chatzeiros is 18 Gerogeros. [Admur 368:3; Michaber 368:1; Rav Yehuda in name of Shmuel Eiruvin 81b] Now, some Poskim rule that this amount calculates to 6 eggs. [Rambam ibid; 1^st opinion in Michaber 368:3 and Admur 368:3] This proves that according to these Poskim, a Gerogeres is 1:3 of an egg. Now, being that an olive is a smaller measurement than a Gerogeres [See Shabbos 91a], therefore we can conclude that a Kezayis is less than even 1:3 of an egg. [Admur ibid]

Other opinions who rule it is even less than a 1:3 of a Kebeitza: Some Poskim rule that the Kezayis is much less than 1:3 of a Beitza. [Rashi and Geonim in Shaareiy Teshuvah, brought in Shiureiy Torah 3 footnote 30] Others rule it is less than ¼ of a Beitza. [Rashba, brought in Shiureiy Torah 3 footnote 29-30]

[9] Shiureiy Torah 3:12

[10] Admur ibid; M”B 486:1; See Kaf Hachaim 486:1; See Shiureiy Torah 2 and 3 footnote 30 that the main opinion is like the Rambam

The reason: As it is ruled in 368 and 409 that the main opinion regarding Eiruv Chatzeiros and Eiruv Techumin follow those who rule that we do not need more than 6 eggs worth of food for the two meals, thus concluding that a Kebeitza is 1:3 of an egg. Now, the reason for this ruling by Eiruvin is because an Eiruv is Rabbinical, and we rule leniently by a Rabbinical matter. However, by Biblical matters one is to be stringent. [Admur ibid]

Other opinions: Some Poskim rule that one is to always be stringent to consider a Kezayis as ½ of an egg, even regarding a Rabbinical Mitzvah. [Implication of Michaber 486:1; Kisei Eliyahu 486:1; P”M 486 A”A; Kaf Hachaim 486:1]

[11] Shiureiy Torah 3:13 footnote 30 that so applies even according to Admur ibid, as proven from Admur 160:13 that we don’t initially enter ourselves into a Rabbinical doubt; Implication of Michaber 486:1; Kisei Eliyahu 486:1; P”M 486 A”A; Kaf Hachaim 486:1

Other opinions: Some rule that one may even initially take 1:3 of a Kebeitza for Rabbinical commands. [Simple implication of Admur ibid; Piskeiy Teshuvos 486:2; Shevach Hamoadim in name of Rav Dworkin; Rav Emanuel Shochat in his introduction to the English Rebbes Hagada; Pamphlet “Pesach Chassidi”]

[12] M”B 486:1; Kaf Hachaim ibid in explanation of Admur ibid; See Shiureiy Torah 3 footnote 30

The reason: As Admur ibid rules that by blessings we follow the rule of Safek Brachos Lihakel and thus we always follow the larger Shiur. Now, since a blessing of Al Achilas Maror is recited over the Maror, one must conclude that Admur’s ruling above is limited to a case of Bedieved, that if he only ate 1:3 of an egg, or is unable to eat more than 1:3 of an egg, that he is Yotzei, however, Lechatchila, he must eat ½ of an egg of Maror in order to be allowed to recite the blessing over it.

[13] M”B 486:1 in name of Chayeh Adam; Piskeiy Teshuvos 486:1

[14] Admur 486:1; P”M 486; M”B 486:1; Kaf Hachaim 486:1; Ketzos Hashulchan 59 footnote 1; Shiureiy Torah 3:12; Shaareiy Rachamim in Minahgei Hagr”a

[15] The reason: As by blessings we follow the rule of “Safek Brachos Lihakel.” [Admur ibid]

[16] One should not eat between 1:3 and a ½ of an eggs size in order not to enter himself into doubt.

[17] Admur 486:2; Rama 486:1; M”A 486:1; Maharil Seder Haggadah p. 111; Sefer Ohel Moed Hilchos Yom Kippur; Mishneh Uktzin 2:8; Rambam Pirush Hamishnayos Eidiyos 1:2; So rule regarding Issur Viheter: Peri Chadash Y.D. 99:6; Peri Toar 99:4; M”B 486:3; Kaf Hachaim Y.D. 98:5 [that one who measures by weight is feeding Treifos to the Jewish people]; Shiurei Torah Siman Alef “It is known and public knowledge from all the Poskim Rishonim and Achronim, that all the measurements of Revius, Kezayis, Kivbeitza, are to be measured in volume and not weight” and in footnote 1 “There are many proofs for this, and I have written all this in length to negate the opinion of the Kaf Hachaim 168:46 that we measure in weight and not volume, as in truth we only measure in weight those foods that had already had their volumes measured and then weighed.”; [However, see Shiureiy Torah p. 184 who writes to measure Matzah by weight; Rav SZ”A says that Rav A”C Naah actually told him to measure by volume, unlike what he wrote above to follow weight. See Seder Hearuch 79 footnote 32]; Piskeiy Teshuvos 486:1; Rav Yaakov Yosef z”l ruled to follow volume and completely negated the following of weight, thus disputing his fathers, and brothers positions.

Other opinions: Some Poskim rule that the all Torah measurements are to be measured in weight and not volume. [Maggid Mishneh Eiruvin 1:12  in name of Teshuvos Hageonim; Pesach Hadvir 130, 190 in name of a number of Poskim, brought in Shiureiy Torah 3:8 footnote 18 and Kaf Hachaim 168:46; Beis David; Mateh Yehuda 168:1; Chida; Vhemdas Yamim; Kaf Hachaim 168:46; 486:1 and 3; See Chazon Ovadia Pesach Hilchos Leil Haseder p. 42 and 73; Rav Yitzchak Yosef Shlita that his father held to always follow weight and that so he asked of him to tell the public in his Shabbos Hagadol Drashos, thus negating his brothers position to follow volume]

[18] Kaf Hachaim 168:46; 486:1 and 3 that so is the widespread custom of Jewry, and all Rabbanim, to measure in weight in order to be Yotzei according to all; Shiureiy Torah 1:1 brings that the Rambam measured a number of items in weight and that from this we can learn regarding other items to measure in weight; Shiureiy Torah 3:8 footnote 18 and page 184 writes to measure the Matzah and bread in weight, and practically gives weight measurements for all his Shiurim, after having compared them with their volume size; Chazon Ovadia Pesach Hilchos Leil Haseder p. 42 and 73; Rav Yitzchak Yosef Shlita that so was the custom of Sephardic Jewry for all generations and that his father held to always follow weight and that so he asked of him to tell the public in his Shabbos Hagadol Drashos, thus negating his brothers position to follow volume

[19] See Shiureiy Torah 3:12-13 and p. 184; Piskeiy Teshuvos 486 footnote 3

[20] See M”B 486:1; Piskeiy Teshuvos 486:1

[21] Opinion brought in M”B 271:68; 486:1 and Biur Halacha 271:13 “Shel Revius” [M”B 486:1 concludes to be stringent by a Biblical Mitzvah] ; Nodah Beyehuda Tzelach Pesachim 116a; Chasam Sofer O.C. 97 and 127; Maaseh Rav 74 and 105; Rav Chaim Volozhin in Shaareiy Rachamim 165; Ashel Avraham Butchach 272; Aruch Hashulchan 168:13 that so is custom

[22] Shiureiy Torah 3:9 it is 53.8cc if the egg is measured without the peel and 3:7 that it is 57.6cc if the egg is measured with the peel; Kaf Hachaim 81:3; 168:46; 486:1; The following Poskim rule that the Kibeitza is 18 Dirham, and each Dirham is equal to between 2.7-3.2 grams, thus totaling approximately 55 grams: Rambam

Other opinions: Some Poskim rule that the Beitza is 44 grams with the peel and 33 grams without the peel. [Mahariv brought in Shiureiy Torah 1:21; 3 footnote 30]

[23] This follows the ruling of the Shiureiy Torah ibid and the Chazon Ish 39:17 that the egg is measured with its peel, however the M”B 486 rules that it is measured with its peel. [See Midos Vishiurei Torah 15:16]

[24] Kaf Hachaim 486:1 that so is custom

[25] M”B 486:1 concludes to be stringent by a Biblical Mitzvah

[26] Shiurei Torah 3:12-13; Kaf Hachaim 168:46; 486:1 in name of Rambam and others that it equals 9 Dirham which is equal to 2.7-3.2 grams, thus totaling approximately 27 grams; Piskeiy Teshuvos 486:1 in name of Midos Vishiureiy Torah writes 27 grams

Shiur Chazon Ish: According to the Chazon Ish, the Biblical Shiur Kezayis is between 45-50cc [depending on whether we measure with the shell of the egg, as stated above] while the Rabbinical Shiur Kezayis is 33cc

Other opinions: Some Poskim rule that the Biblical Kezayis is 15 grams. [Custom of many in Ashkenaz prior to ruling of Tzelach, based on Mahariv, brought in Shiureiy Torah 1:21; 3 footnote 30]

[27] Kaf Hachaim 168:46; 486:1

[28] See Shiureiy Torah 3:12-13 footnote 26 based on Chulin 103 that by all Issurin, the food stuck in the teeth is not included; Minchas Chinuch Mitzvah 6 and 10; Matzos Mitzvah 12:23; Piskeiy Teshuvos 486:1; Heard from Rav Yitzchak Yosef in name of his father Rav Ovadia Yosef

Food stuck on gums: Does join the Shiur Kezayis:Kebeitza. [Chasam Sofer 127; Kesav Sofer 96]

Other opinions: Some Poskim rule that food stuck in between the teeth does join the Kezayis. [See Maharam Shick 250 that the benefit of the mouth joins the Shiur]

[29] Chayeh Adam 50:20; Zechor Leavraham 2; SSH”K 54 footnote 71; Yechaveh Daas 6:14; Mishneh Halachos 4:29; 5:36; Shraga Hameir 3:4; Igros Moshe 2:109 [permits by even if a less than the amount for certain]; Piskeiy Teshuvos ibid footnotes 179

[30] Admur Seder 8:1; Luach 2:1; M”A 210:2 and 5; Taz 210:1; Bach 210; Rosh 14:5; Rif; Drashos Maharil Hilchos Agada; Chok Yaakov 472:11; Elya Raba 210:8; 472:13; Chok Yosef 472:10; P”M 472 A”A11; Kaf Hachaim 472:57; Ketzos Hashulchan 59:5

[31] A lug is a biblical liquid measure of volume, often mentioned in Tanach in reference to wine or oil offerings. Its measure is equivalent to six eggs, and it equals 1/4^th of a kav, 1/24^th of a se’ah, 1/72^nd of an ephah, 1/720 of a bechor. [Rashi Shemos 16:36; Rambam Mikvaos 6:13] in our modern measurements: according to the opinion of the RAC”N, it is approximately 345 cc (cubic centimeters); according to our view based on the measurements of the Rambam, approximately 300 cc; and according to the view of the Chazon Ish, approximately 600cc.”

^[32] Admur 472:18; Tur 472; Levush 472:9; Rav Chisda Pesachim 109a; Kaf Hachaim 472:57

Other opinions: See Rebbe Yosa in Yerushalmi Pesachim 10:1 that the measurement is 2×2 fingers by 1.88 Etzba height

[33] Some Poskim rule that the finger is 6 barley kernels worth [Admur after the retraction, as recorded in Sheiris Yehuda Y.D. 11 and Tzemach Tzedek 102 and 320] which is equivalent to 2 centimeters in length. [See list of Poskim, Geonim, Rishonim and Achronim in Shiureiy Torah 1:1 footnote 8 page 75; 3:25 footnote 58 page 249 and also page 16; Tikunei Mikvah p. 89 and 93 that the Shiur of Admur after the retraction is 2.16 cm; See Shiureiy Mikvah p. 83 who negates this opinion; The tradition of the Rebbe Rashab is that it is 2.22 cm; Another tradition is that it is 2.3 cm] Thus, a square cup is 4×4 with a height of 5.4 centimeters, while a round cup is 4×4 with a height of 7.6 centimeters. [Shiureiy Torah ibid page 75] Other Poskim rule that the finger is seven barley kernels worth [Admur 190:13; See Poskim in Shiureiy Torah ibid] worth which is equivalent to 2.5 cm. [See Tikunei Mikvah p. 88 and 93] Thus, a square cup is 5×5 with a height of 6.75 centimeters, while a round cup is 5×5 with a height of 9 centimeters. 

[34] See Shiureiy Torah 3:6 and in chapter 1 in length; Koveitz Yagdil Torah NY 60 p. 263-264 in a Ksav Yad of Tzemach Tzedek in name of Admur; Kitzur Hilchos Shabbos Miluim p. 18; Tikkunei Mikvaos [Levin] chapter 10 p. 93

The ruling of Admur: There is a difference in ruling recorded between what Admur ruled in his Shulchan Aruch regarding the measurement of an Etzba versus what he ruled later on in his advanced age, as recorded in Sheris Yehuda Y.D. 11 and Tzemach Tzedek 102 and 320. In the Shulchan Aruch Nida 190:13 he ruled that the Etzba is 7 barley kernels worth, while in his advanced age he ruled that it is 6 barley kernels worth. [See Shiureiy Torah ibid; Tikkunei Mikvaos ibid] Now, while all agree that the measurement of the retraction is smaller than that of Admur’s original ruling in his Shulchan Aruch, there exists various opinions and traditions in Chabad as to its exact centimeter measurement and consequential fluid measurement even if we follow his retraction. One tradition has it that Admur stated that the Satka of Nikolaiy is the measurement of a Revius. [Shiureiy Mikveh p. 83] Rav Avraham Chaim Naah in Shiur Torah insists that the measurement remains of the finger remains as 2 centimeters. Other traditions are recorded from the Tzemach Tzedek, Rebbe Rashba and Rebbe Rayatz, as will be explained. Practically, the Shiur Revius according to Chabad tradition and understanding of Admur varies between: 86.6 milliliters, 99 milliliters, 108.8 milliliters, 115.2 milliliters, 118 milliliters, 120 milliliters, to 123 milliliters.

[35] Rav Avraham Chaim Naa”h in Shiureiy Torah 3:6 p. 96 and Shiurei Mikveh p. 81-83 based on retracted ruling of Admur in Sheiris Yehuda Y.D. 11 and ruling of Rambam that a Revius contains 27 Draham; This follows the Grach Na’ahs opinion in the Shiur Kibeitza which is 57.7 grams, and thus a Revius equals 86.6 milliliters which is equivalent to 1.5 eggs with their peel, as rule the Poskim ibid in previous footnotes; Maharsham 9:8

[36] Rav Mazuz; Rav Ovadia Yosef; See Shiureiy Torah 3 footnote 58 [page 250] that this possibility is mentioned

[37] Ruling of Geonim, brought in Shiureiy Torah ibid

^[38] Tradition of Rav Eliyahu Landa Shlita, based on tradition from Admur that the Satka of Nikolaiy is the measurement of a Revius, and that the Satka contains 99 milliliters. Shiureiy Mikveh p. 83 that the Kiddush cup of the Rebbe Raytaz contained 100 milliliters

^[39] Tikkunei Mikvaos p. 93 based on calculation of retracted ruling of Admur in Sheiris Yehuda Y.D. 11 that each Etzba is 2.16 cm

^[40] Tradition from Tzemach Tzedek in name of Admur, brought in Shut Tzemach Tzedek O.C. 84; See Tikkunei Mikvaos ibid

^[41] Tikkunei Mikvaos p. 93 based on ruling of Rebbe Rashab that the Etzba is 2.22 cm

^[42] Shiureiy Mikveh p. 83 based on tradition from Admur that the Satka of Nikolaiy is the measurement of a Revius, and some say the Satka contains 120 milliliters.

^[43] Tikunei Mikvaos p. 94 based on tradition from Admur that the Satka of Nikolaiy is the measurement of a Revius, and some say the Satka contains 123 milliliters.

^[44] Chazon Ish in Kuntrus Hashiurim and in letter to Gr”ach Naah that so was custom in Lita, and is based on all the following Poskim who rule Niskatnu Habeitzim: Opinion brought in M”B 271:68; 486:1 and Biur Halacha 271:13 “Shel Revius”; Nodah Beyehuda Tzelach Pesachim 116a; Chasam Sofer O.C. 97 and 127; Maaseh Rav 74 and 105; Rav Chaim Volozhin in Shaareiy Rachamim 165; Ashel Avraham butchach 272; Aruch Hashulchan 168:13 that so is custom;

^[45] Tikkunei Mikvaos p. 93 based on Admur in Y.D. 190:13 [prior to his retraction] that the Etzba is 7 barley kernels worth

^[46] See Visein Barcha p. 248 and Piskeiy Teshuvos 201:1 that so was the widespread custom of the world to follow 86 milliliters as the Shiur Revius, as evident from the Kiddush cups of many Gedolei Yisrael, including the Chofetz Chaim; Yechaveh Das 4:25 that so was the widespread custom in all Sephardi communities; Rav SZ”A in Halichos Shlomo 2:90 “The main opinion is like the Grach Naah, and so is the old age custom”; Rav Elyashiv Koveitz Teshuvos 2:30 “I have already publicized my opinion that the accepted Shiur is like the Grach Naah”; Shevet Halevi 6:60 that from the Setimas Haposkim it is implied unlike the Tzelach

^[47] As rules M”B ibid and ibid regarding Lechtachila for Biblically rooted Mitzvos; See Piskeiy Teshuvos ibid that although today many people have taken upon themselves the 150 milliliters Shiur of the Chazon Ish, nevertheless, Bedieved if one only drank 86 milliliters a n after blessing is to be said.

Ruling of Mishneh Berurah: See M”B 271:68; 486:1 and Biur Halacha 271:13 “Shel Revius” where he arbitrates to initially suspect for this opinion by all possible Biblical Mitzvos [i.e. Kiddush of Shabbos night, Havdala, however not for blessings and Rabbinical Mitzvos]. To note, however, that his own Kiddush cup was not this Shiur!

[48] Admur in Seder 8:1; Luach 2:1; Michaber 210:1; Rambam Brachos 3:12

[49] See Admur in Seder 8:6; Luach 2:7; 472:20; 612:15; Shiureiy Torah 3:15; Practically, the Revius must be consumed within 3-4 minutes to say an after blessing.

[50] See regarding Kiddush: Admur 271:20; 28; M”A 271:23; See regarding Havdalah: Admur 296:13See regarding four cups on Pesach: Admur 472:17; Michaber 472:9; Pesachim 108b and Rashbam ibid, Ran ibid; Beis Yosef 472; Bach 472; M”B 472:62; Kaf Hachaim 472:62

[51] Admur 472:19; See Piskeiy Teshuvos 472:8

[52] Admur 271:24; 472:19; See also 190:4; Michaber 271:13; Rav Huna Pesachim 107a; Ketzos Hashulchan 79:5

[53] Admur 273:9; 274:8; 286:4; Rama 273:5

[54] Nimukeiy Orach Chaim 529; Torah Or Esther p. 198 “One fulfills his obligation of Simcha through drinking a Revius of wine.”

[55] Admur Seder 8:11 “Even if he tastes a lot, up until a Revius, not including a Revius” and Luach 8:12 “Even if he tastes a lot, up until a Revius”; Ohel Moed Shaar Brachos 1:4 brought in Beis Yosef 210; Interpretation of Braisa Brachos 14a “Tasting does not need a blessing, up until a Revius”; Semag, brought in Erech Hashulchan 210:7 and Kaf Hachaim 210:30; This possibly follows the 1^st opinion in Michaber ibid and Tur 210 in his Stam:main opinion and the Rif and Rambam Brachos 1, as they can be interpreted to be referring even to spitting out a Revius that a blessing is required, and so learns Ateres Zekeinim 210, however see Beis Yosef 210 brought in other opinions

Other opinions: Some Poskim rule a blessing is never recited upon tasting a food without swallowing it, even if it is more than a Revius of food. [2nd opinion in Michaber ibid; Tosafus in name of Rabbeinu Chananel; M”A 211:7 and 10 that this is the main opinion; Rama ibid concludes that Safek Brachos Lihakel. This means that a blessing is not to be recited upon tasting a food unless one a) swallow the food as requires second opinion and b) eats a Revius as requires the first opinion. [Ateres Zekeinim 210 in explanation of Rama ibid] Some Poskim rule that even according to the 1^st opinion in Michaber ibid and Tur 210 in his Stam:main opinion and the Rif and Rambam Brachos 1 a blessing is never said unless one swallows, even if he tastes a Revius, and they only argue if one swallows less than a Revius. [Beis Yosef 210 in argument against Ohel Moed ibid; M”B 210:15]

[56] Siddur Seder Netilah; Kama 4:1; 159:3; 160:16; and Seder Netila 12 regarding washing for bread.

^[57] Based on Siddur Seder Netilah; Biur Hagra 4:7 in name of Rieh; Rashash in Nehar Shalom; Ruach Chaim 5:5; Kaf Hachaim 4:26

Background of ruling of Siddur: Admur writes in the Siddur that all the laws of washing for a meal equally apply for the morning washing. In 159:3 and 160:16 Admur rules regarding washing for bread that the vessel must contain a Revius of water for it to be valid and hence the same would apply for the morning washing.

Other opinions-Ruling of Kama: In Kama 4:3 Admur rules: “If one does not have a Revius of water available he may nevertheless wash with a blessing being that the Sages did not differentiate [in the amount of water], as one is nevertheless washing with valid water.” This follows the ruling of Michaber 4:6

[58] Ruach Chaim 77 brought in Kaf Hachaim 4:33; Toras Yekusiel 2; Beir Moshe 8:39 mentions nullifying in majority

If two people washed: If two people washed hands, then one requires two Revius of water to nullify it. [Kaf Hachaim ibid]

Other Opinions: Toras Yekusiel ibid brings Rabbanim who rule that even adding water does not help.

[59] Admur159:3; 160:16; and Seder Netila 12

^[60] Admur 76:1; Michaber 76:1

^[61] See Admur 99:1-3

^[62] See Admur 128:51

^[63] Admur 197:3 and 198:2

[64] See Admur and Michaber 612:4; Shiurei Torah 3:15; Piskeiy Teshuvos 475:10

[65] Seder 8:2; Luach 2:2; Negaim 13:9; Eiruvin 4a; See also Admur 618:14; 81:1; Toras Menachem on Seder ibid; Chazon Ish O.C. Kuntrus Hashiurim 39:18

[66] Seder ibid; Luach ibid; Rashi Sukkah 42b

[67] Seder ibid; Luach ibid; Negaim ibid; Eiruvin ibid; Chazon Ish O.C. Kuntrus Hashiurim 39:18

[68] Seder ibid; Luach ibid; Rashi ibid

[69] Admur 612:4

[70] Seder Birchas Hanehnin 8:2 in parentheses regarding after blessing; Luach 2:2; Admur 442:1 in parentheses regarding Taaruvos Chametz; Gloss on Mitzvah 6 in Hakdamah to Hilchos Pesach regarding Taaruvos Pesach; Admur 475:8 regarding Matzah; 2^nd opinion in Admur 612:4 “Around three eggs worth not in a dense manner but rather open and spacious”; 2^nd opinion in Michaber 612:4; Rama 612:4; Rambam Shevisas Assur 2:4; Chametz Umatzah 1:6; Rashba Toras Habayis Haruch 4:1-12; Rebbe Yochanon Ben Beroka in Mishneh Eiruvin 82b

[71] 1^st opinion in Admur 612:4 “Around four eggs”; 1^st opinion in Michaber 612:4; Tur 612; Rashi Yuma 80b; Rebbe Shimon in Mishneh Eiruvin 82b

[72] Admur 612:4; M”B 612:8

[73] Seder Birchas Hanehnin 8:2; Luach 2:2

[74] Admur 612:4; M”B 612:8

[75] Admur 475:8 regarding Matzah; regarding after blessing

[76] Admur 475:8 regarding Matzah; regarding after blessing

[77] For a full overview on this subject: See Shiurei Torah 3:15; Sefer Haminhagim ibid and footnotes 342-344; Piskeiy Teshuvos 158:7 and 210:1; 271:9; 475:10

Chabad custom: See Gulot Ariel Chidushei Mishnayos Mikvaos 10:7 in name of Alter Rebbe that the Shiur is two minutes per Beitza for a total of 6 minutes for Rabbinical food Mitzvos and 8 minutes for Yom Kippur [See Shiuriei Torah p. 204]; See Sefer Haminhagim ibid and footnotes 342-344 for a quote of various opinions of Achilas Peras, and for a tradition from the Tzemach Tzedek, in name of Rav Hillel Miparitch, that differs from the response of the Tzemach Tzedek which placed Achilas Peras as 6-7 minutes and rather places Achilas Peras as minimum 3 minutes and maximum 7 minutes. The Rebbe concludes there in the footnote that one is required to suspect for the above tradition. Accordingly, one should try to eat the Kezayis within three minutes. However, if one ate it within four minutes, and perhaps even within 6-7 minutes, one can rely on the Tzemach Tzedek’s other rulings. Vetzaruch Iyun, as perhaps Safek Brachos Lihakel. In any event one is to be very careful in the above.]

[78] Rav Y.Y. Kanievsky in Shiuran Shel Torah Shiureiy Hamitzvos 30

[79] Igros Moshe 4:41 in name of Marcheshes; Orchos Rabbeinu p. 70 that so was custom of Chazon Ish; Sefer Haminhagim ibid and footnotes 342-344 in tradition from the Tzemach Tzedek, in name of Rav Hillel Miparitch, that the minimum of Achilas Peras is 3 minutes and maximum 7 minutes. The Rebbe concludes there in the footnote that one is required to suspect for the above tradition.

[80] Shiurei Torah 3:15 [p. 303]; Aruch Hashulchan 202:8; Kaf Hachaim 210:5; Piskeiy Teshuvos 210:1 that so is the widespread custom

[81] Some Poskim rule that the Shiur of Kdei Achilas Peras is 6-7 minutes. [Tzemach Tzedek Shaar Hamiluim 1:8-10, brought in Ketzos Hashulchan 36 footnote 5; 59 footnote 4; Shiureiy Torah ibid footnote 35; Sefer Haminhaghim [English] p. 93 regarding Tishe Beav] Other Poskim rule that the Shiur of Kdei Achilas Peras for 4 Kebeitzim [i.e. Yom Kippur] is 8 minutes, while the Shiur for eating Mitzvos or after blessing is 6 minutes. [Gulot Ariel Chidushei Mishnayos Mikvaos 10:7 in name of Alter Rebbe “I received in the name of my great uncle, the Alter Rebbe, that the Shiur is eight minutes, as he measured the eating an egg by an average person and it took two minutes, and so is my custom to rule”]

[82] Chasam Sofer 6:16; Tzemach Tzedek Shaar Hamiluim 1:8-10, brought in Ketzos Hashulchan 36 footnote 5; M”B 618:21; Shiurei Torah 3:15 [p. 203]; Aruch Hashulchan 202:8; Kaf Hachaim 210:5; Piskeiy Teshuvos 210:1; Sefer Haminhagim ibid and footnotes 342-344; See Shiurei Torah 3:15; Piskeiy Teshuvos ibid

[83] Shiurei Torah 3:15 that the custom is 4 minutes; Rav Avraham Elyashvili in footnote 24 that if eat in more than 4 minutes forfeits after blessing as Safek Brachos Lihakel ; See next footnote

[84] Shiurei Torah 3:15 Footnote 35 p. 207

^[85] Chasam Sofer 6:16; M”B 618:21; Shiurei Torah 3:15 [p. 203]; Aruch Hashulchan 202:8; Kaf Hachaim 210:5; Piskeiy Teshuvos 210:1; Sefer Haminhagim ibid and footnotes 342-344

Opinion of 6-8 minutes: The Tzemach Tzedek [Shaar Hamiluim 1:8-10] records 6-7 minutes regarding the Shiur of Achilas Peras. [Ketzos Hashulchan 36 footnote 5; 59 footnote 4; Shiureiy Torah ibid footnote 35; Sefer Haminhaghim [English] p. 93 regarding Tisha B’av] The above response however is only regarding Tishe Beav, where we can follow the lenient opinion that there are only 3 eggs in a Peras, however by Yom Kippur in which we need to follow the opinion that there are 4 eggs in a Peras, then according to the Tzemach Tzedek it would be 8 minutes. [See Shiureiy Torah ibid footnote 35 that according to Admur and Tzemach Tzedek it is 2 minutes per Peras.]

[86] Conclusion of Rebbe in Sefer Haminhagim [English] p. 93 to suspect for three minutes; Conclusion of four minutes: Shiureiy Torah 3:15 [p. 303] and Piskeiy Teshuvos 210:1 that so is the widespread custom; See Piskeiy Teshuvos 475 footnote 53 that if one is in doubt if he ate it within 4 minutes then he is not required to re-eat, and may rely on the other opinions Chabad custom: See Gulot Ariel Chidushei Mishnayos Mikvaos 10:7 in name of Alter Rebbe that the Shiur is two minutes per Beitza for a total of 6 minutes for food Mitzvos and 8 minutes for Yom Kippur [See Shiuriei Torah p. 204]; See Sefer Haminhagim ibid and footnotes 342-344 for a quote of various opinions of Achilas Peras, and for a tradition from the Tzemach Tzedek, in name of Rav Hillel Miparitch, that differs from the response of the Tzemach Tzedek which placed Achilas Peras as 6-7 minutes and rather places Achilas Peras as minimum 3 minutes and maximum 7 minutes. The Rebbe concludes there in the footnote that one is required to suspect for the above tradition. Accordingly, one should try to eat the Kezayis within three minutes. However, if one ate it within four minutes, and perhaps even within 6-7 minutes, one can rely on the Tzemach Tzedek’s other rulings. Vetzaruch Iyun, as perhaps Safek Brachos Lihakel. In any event one is to be very careful in the above.]

[87] See Piskeiy Teshuvos 475:10 that one may be lenient up until five minutes and for a child or one who is sick or weak up until nine minutes. This follows the ruling of Admur ibid that by Rabbinical commands one can be lenient to consider Achilas Peras as 4 Kibeitza of bread.

[88] So rule regarding the dispute of the size of a Kezayis [See Halacha C], and the same would apply here as well regarding the Shiur Achilas Peras: See Shiureiy Torah 3:13; M”B 486:1; Kaf Hachaim 486:1 in explanation of Admur ibid; Piskeiy Teshuvos 486:2

[89] See Piskeiy Teshuvos 475:10 that one may be lenient up until five minutes and for a child or one who is sick or weak up until nine minutes. This follows the ruling of Admur ibid that by Rabbinical commands one can be lenient to consider Achilas Peras as 4 Kibeitza of bread.

[90] So rule regarding the dispute of the size of a Kezayis [See Halacha C], and the same would apply here as well regarding the Shiur Achilas Peras: See Shiureiy Torah 3:13; M”B 486:1; Kaf Hachaim 486:1 in explanation of Admur ibid; Piskeiy Teshuvos 486:2

[91] Piskeiy Teshuvos 475:10 that so rule all Poskim