The minimum amount of any food that obligates one to recite Birkas ha-
Mazon or a berachah acharonah is a k'zayis, an amount of food that equals
the size of an olive. But how to measure and determine the precise amount
of a k'zayis is the subject of heated debate. For the purpose of hilchos
berachos, we follow the view of the poskim who hold that that a k'zayis is
the amount of food that fills a cup which holds one fluid oz., or 29.5 cc.
To give us a better sense of what a k'zayis of bread is in reality,
consider the following: There are about ten k'zaysim in a bagel or in an
onion roll, nine in a challah roll, four in a middle slice of a 2 lb. loaf
of rye bread or in a pita bread, three in a slice of white bread, and a
little more than two k'zyasim in a piece of machine matzah.
In the following pages we will discuss some of the halachos that pertain
to the amount of food that is required for Birkas ha-Mazon and Al ha-
WHEN EATING BREAD:
* Washing hands is required before eating at least a k'zayis, and is
strongly recommended when any amount of bread is eaten.(2)
* Al netilas yadayim, the blessing over washing hands, is recited when
eating at least two k'zaysim.(3) Some poskim hold that a blessing may be
recited even for a k'zayis,(4) and one may follow this view if need be.(5)
* Ha-Motzi is recited before eating any amount of bread, regardless if one
washed or recited Al netilas yadayim .(6)
* Birkas ha-Mazon is recited after eating a k'zayis of bread(7) within a
time-span of no longer than 3-4(8) minutes. One who is unsure whether or
not he ate a k'zayis of bread within 3-4 minutes should not recite Birkas
WHEN EATING BAKED GOODS AS A SNACK:
* Mezonos is recited before eating any amount of baked or cooked food made
out of any one or combination of the five species of grain.
* Al ha-michyah is recited when a k'zayis is eaten within a time-span of
no longer than 3-4 minutes.(10) The k'zayis must be composed entirely of
flour the other ingredients do not count towards the minimum).(11) Many
people, however, are not accurate in ascertaining the exact amount of
flour they ate and some poskim find a source to excuse their inexactitude
(12) if at least the majority of the mixture is pure flour.(13) Fillings
such as cream in a seven layer cake, apple filling in a pie, or cheese in
a cheese cake, are certainly not counted as part of the k'zayis.(14)
WHEN EATING BAKED GOODS AS A MEAL:
Washing hands, reciting Al netilas yadayim, and reciting Birkas ha-Mazon
are required when eating an amount of baked goods that constitutes kevius
seudah, i.e., an amount of food that has the halachic status of eating a
regular meal (as opposed to a snack). When one eats such a substantial
amount, the baked goods are halachically treated like bread.
Important Note: When we refer to baked goods, we are speaking of products
such as cake or other baked goods known as pas haba b'ksinin, which
have "bread-like" properties and appearance, e.g., cookies, crackers,
pretzels, Cheerios, etc. However, pasta, blintzes, farfel, oatmeal cereal
and other cooked mezonos items which do not resemble bread at all are not
considered baked goods for the purpose of our discussion.
There are several opinions as to the amount of baked goods which is
necessary for kevius seudah. Some poskim rule that one who ate as little
as eight k'zaysim is obligated to bentsch. Others hold that Birkas ha-
Mazon is not recited unless one eats an amount of baked goods equal to the
amount of bread he would eat at a main meal. It is exceedingly difficult
to figure out what this amount is, since the amount of bread one would eat
at a main meal varies according to the differences in eating habits
between men and women,(15) different age groups,(16) and different
localities.(17) A rough estimate, however, is an amount similar to two
bagels, or five middle pieces of a 2 lb. loaf of bread, or about eighteen
to twenty k'zaysim.(18)
In general terms, the halachah breaks down as follows. One who eats an
amount of baked goods:
* Between one to eight k'zaysim recites Al ha-michyah.
* Over twenty k'zaysim - must wash his hands, recite Al netilas yadayim
and recite Birkas ha-Mazon.
* Between eight and twenty k'zaysim (an halachicaly questionable area),
and feels satiated from this amount of food, should recite Birkas ha-
Mazon. If he does not feel satiated, he should recite Al ha-michyah.(19)
[If he is satiated but only because he ate other foods as well at the same
time, see follow-up Question and Discussion.]
Here are some practical examples:(20)
* A slice of pizza(21) contains about eight to nine k'zaysim of flour.
Typically, a single slice is eaten as a snack and one does not become
satiated from it; Al ha-michyah is recited. In the case when it is eaten
as a substitute for lunch and the person is satiated from it, Birkas ha-
Mazon is required. But if one eats two slices of pizza, which, for most
people would constitute a meal, one must definitely bentsch. In the
atypical case where one is not satiated from eating two slices, Al ha-
michyah will suffice. But one who eats more than two slices is required to
bentsch even if he is not satiated from that amount of pizza.
* A standard cupcake is four k'zaysim. One who ate two cupcakes and is
satiated is required to bentsch. If, however he is not satiated, he could
eat up to five cupcakes before it would be mandatory to recite Birkas ha-
* A slice of a standard (3"x3") seven layer cake an inch thick contains
two k'zaysim of flour. One may eat four such slices before running into a
question of reciting Birkas ha-Mazon. At what point bentsching is
mandatory will depend on how many slices one needs to eat in order to feel
satiated. Eating ten such pieces, however, would require bentsching no
matter the degree of satiety.
QUESTION: We mentioned earlier that eating one slice of pizza would
not necessitate Birkas ha-Mazon since often one is not satiated from it.
What if one ate a portion of French fries (four medium-sized French fries
total a k'zayis) along with the pizza and is now satiated from the
combination of the two foods - is he required to bentsch?
DISCUSSION: It depends on how the foods were eaten. If the pizza
and the French fries are eaten together as when bread is eaten together
with fish or meat, then we view the pizza as a "bread," since it is acting
as a bread substitute. In that case, Birkas ha-Mazon is required, since
one became satiated from a meal with a bread substitute. But if the pizza
and the French fries were eaten separately - independent of each other -
then the pizza did not serve as a substitute for bread but rather as a
separate food; no Birkas ha-Mazon is required. Al ha-michyah and Borei
nefashos are said instead.
In other words, for other foods to be counted as part of the kevius
seudah and require Birkas ha-Mazon, three conditions must be met: 1) One
must be satiated. 2) At least eight k'zaysim of baked goods must be eaten.
(22) 3) The other foods are eaten together or along with the baked goods.
A number of examples to illustrate this point:
* A croissant (made with pure fruit juice for the purpose of a snack)
eaten by itself, or at the beginning or end of the meal is mezonos/Al ha-
michayah.(24) But if it is eaten together with other foods (e.g., at a
lunch together with fish and vegetable salads), and is used as a
substitute for bread, Birkas ha-Mazon is required - if one becomes
satiated from eight k'zaisyim of croissant roll plus any amount of the
other food served at the meal.
* Baked goods which are served as an appetizer and removed from the table,
or as a desert after the meal is cleared away, are not being used as bread
substitutes. The other foods do not count towards the amount of kevius
* Tuna fish or chopped liver served together with crackers or flat bread
are counted towards the amount of kevius seudah. Thus if one ate eight
k'zaysim of crackers (about 48 Tam Tams) or flatbread (about 14 pieces)
plus tuna fish or chipped liver and he is satiated, he must recite Birkas
Note: The subject discussed here, the formula for determining kevius
seudah when combining baked goods with other foods, is an issue intensely
debated by the poskim, and there are numerous, often conflicting,
approaches. While the approach that we took is based on the decision of
several leading poskim,(25) it is by no means the one and only approach.
There are more lenient views who hold that the entire amount of kevius
seudah must be composed of the baked goods only; other foods do not count
at all.(26) There are also more stringent views who hold that Birkas ha-
Mazon is recited even when the baked goods are eaten at any time during
the meal (and not only if they are eaten together or along with the baked
goods), and even if the total amount of baked goods is less than eight
k'zaysim.(27) We have chosen a middle-of-the road compromise, which seems
to be the prevalent custom, and it is based on the halachic decisions of
Harav S.Z. Auerbach.(28)
1 Based on the calculations of Halachos of K'zayis, pg.17-20; 86-88.
2 Mishnah Berurah 158:10.
3 Mishnah Berurah 158:9.
4 Beiur ha-Gra quoted in Sha'ar ha-Tziyun 158:9.
5 Igros Moshe, O.C. 4:41; Harav Y.S, Elyashiv (quoted in Vezos ha-
Berachah, pg. 15 and pg. 347).
6 Shulchan Aruch Harav 168:7.
7 O.C. 184:6. This is a Rabbinic obligation. Biblically, one does not
recite Birkas ha-Mazon unless he has eaten a meal which satiates him.
8 The exact amount of time is in dispute, so l'chatchilah three minutes
should be the limit. B'diavad, however, there are many poskim who permit
reciting Birkas ha-Mazon if a k'zayis was eaten in four minutes.
9 Mishnah Berurah 184:15. It is proper, however, to wash and eat more
bread so that Birkas ha-Mazon can be recited; ibid.
10 O.C. 208:9.
11 See Igros Moshe, O.C. 1:71 and E.H. 1:114; Divrei Yoel 1:13; Harav Y.S.
Elyashiv (quoted in Vezos ha-Berachah, pg. 46). This is also the ruling of
the Brisker Rav (quoted in Teshuvos v'Hanhagos 1:132).
12 Mishnah Berurah 208:48; Chazon Ish, O.C. 26:8.
13 Harav S.Z. Auerbach (quoted in Vesein Berachah, pg. 530).
14 Minchas Shelomo 1:91-4. See also Halachos of K'zayis, pg. 134 and
Yalkut Yosef 3:491.
15 Harav S.Z. Auerbach (Vesein Berachah, pg. 488) rules that women and
girls who eat less than men have a smaller shiur of kevius seudah.
16 See Beiur Halachah 168:6, who rules that kevius seudah for children and
elderly people varies according to their individual eating habits.
17 Igros Moshe, O.C. 3:32.
18 There are several factors and many views which must be taken into
account when calculating this amount. See Vezos ha-Berachah, pg. 28-36 and
pg. 219-226 for a lengthy explanation of this very difficult subject. See
also Pischei Halachah 8:15-21.
19 Mishnah Berurah 168:24.
20 Based on the calculations of The Halachos of K'zayis, pgs. 31-41.
21 Our Discussion follows the opinion which holds that when pizza is eaten
as a snack its berachah is mezonos/Al ha-Michyah. While many poskim hold
that one always bentsches over pizza, the custom seems to follow the first
23 Derech ha-Chayim (Mezonos 3); Mishnah Berurah 168:24; Emes l'Yaakov,
O.C. 168, note 196; Minchas Yitzchak 1:71-10; Harav C.P. Scheinberg
(quoted in Vezos ha-Berachah, pg. 32); Teshuvos v'Hanhagos 2:125; Lehoros
Nossan 7:9. This may be the view of the Chazon Ish as well; see O.C. 26:8;
34:8, Orchos Rabbeinu 1:80 and Pischei Halachah 8:21, note 53. See Vezos
ha-Berachah, pg. 36 and 220, for an elaboration.
24 See Shevet ha-Levi 8:32.
25 See notes 22 and 23.
26 Birkei Yosef 168:6; Aruch ha-Shulchan 168:17; Kaf ha-Chayim 168:47.
Sefaradim conduct themselves according to this view; Yabia Omer 8:22-21.
27 Igros Moshe, O.C. 1:56; 3:32 and 4:41; Harav Y.S. Elyashiv (quoted in
Vezos ha-Berachah, pg. 32 and 34); Mekor ha-Berachah, pg. 113.
28 Harav Auerbach's ruling on the subject may be found in Shemiras Shabbos
K'hilchasah 54, note 132, Vesain Berachah, vol. 2, Hebrew section, pg. 10
and pg. 490, and Vezos ha-Berachah, pg. 32.