The following is a discussion of Halachic topics related to the Parsha of the week.
For final rulings, consult your Rav.
MATZAH - HOW MUCH NEED WE EAT?
QUESTION: How much Matzah must one eat on Seder night?
DISCUSSION: There is a Biblical commandment to eat matzah on the first
night1 of Pesach. The Talmud explains that "eat", by definition, means to
eat at least an amount equivalent to the size of an olive, a k'zayis. Men
and women equally are obligated to perform this mitzvah. Boys and girls,
too, once they are old enough to understand what the Seder is all about,
should be taught to eat a portion of matzah lishmah, "for the sake of the
mitzvah", as the Torah requires.
In the opinion of many authorities, the proper, l'chatchillah manner of
eating the k'zayis of matzah is to chew the matzah thoroughly and swallow it
entirely in one swallow(2). If it is difficult to do so(3), however, one may
take up to three(4) minutes(5) to eat the kzayis. [An elderly person who is
only able to chew slowly, children under the age of bar/bat mitzvah(6), or
anyone with a medical condition, can rely on the lenient views which allow
for a time-span of up to nine minutes.]
It follows, therefore, that anyone who eats one k'zayis of matzah within
the prescribed time satisfies his basic obligation. But while the basic
mitzvah is easy to understand and fulfill, there is much discussion among
the poskim concerning several technical details of how best to perform this
important mitzvah: Some of the issues debated are:
Should the k'zayis of matzah be broken off from the upper, whole matzah, or
from the middle, broken matzah?
Can two blessings - ha-motzi and al achilas matzah - be recited over one
matzah7, or must we recite one blessing over one matzah and the other
blessing over the other?
If, indeed, the two blessings must be recited over two separate matzos,
which blessing is said over which matzah?
In response to these and other concerns and in order to fulfill the mitzvah
in the most l'chatchillah manner(8), Shulchan Aruch advises that one eat two
k'zayis portions, one from each matzah. But since we are unsure which is the
"real" k'zayis, nor are we sure which blessing corresponds to which matzah,
we recite both blessings over both pieces of matzah (the top and the middle
one(9), break them off together(10), and eat a k'zayis from each one of them
together(11). ["Together" means inserting both k'zayis portions into one's
mouth and chewing them, and then swallowing one k'zayis at a time, if
possible. If it is difficult to insert both k'zayis portions into the mouth
at one time, one can take up to three minutes to swallow both portions12.]
Thus one is actually eating two kzayisim.
But it is essential to understand that eating a second k'zayis is not
nearly as important as eating a first one. Clearly and unequivocally, one
fulfills his basic obligation by eating any k'zayis of any matzah,
regardless of which matzah or combination of matzos it is taken from.
Bearing this in mind, the following points need to be clarified:
There are poskim who question this entire stringency(13) and require only
one k'zayis to be eaten(14).
Even among the poskim who recommend that two portions be eaten, there are
several who hold that only the person conducting the Seder [or anyone
breaking the matzos and reciting the blessings over them] must eat two
portions. The other participants need to eat only one portion(15).
While many poskim seem to hold that everyone should eat two k'zaiysim(16),
it is, according to all views, a stringency and a hiddur mitzvah, not a
basic halachic obligation. Thus elderly or weak people, people who can only
stomach a small amount of matzah, small children, and anyone else who finds
eating matzah difficult, need not force themselves to eat more than one
k'zayis of matzah. [The k'zayis should be a combination of the top and
One who is able to eat two portions, but cannot eat them together or even
within three minutes, should eat them separately, each one within three
minutes. He should first eat the k'zayis which comes from the upper, whole
matzah, and then the kzayis which is taken from the middle matzah(17).
HOW MUCH IS A K'ZAYIS?
The amount of a k'zayis as it pertains to matzah has been extensively
debated among the classic poskim and contemporary authorities. We will list
briefly the points debated:
Is a k'zayis the equivalent of half an egg, like the Rosh writes, or a third
of an egg, like the view of the Rambam?
Are the eggs today the same size they were during the days of the Talmud or
are they smaller, as some evidence seems to indicate?
Is the k'zayis measured by weight or by volume? (In other words, do we
include air holes when measuring the k'zayis or not?)
When measuring an egg, what size egg is used? Is the shell included when
measuring the egg?
There are no clear-cut, definitive answers to these questions. While several
poskim allow for the lesser amount, the view of the Mishnah Berurah is that
when it comes to matters of Biblical law, such as the mitzvah of eating
matzah, we ought to be stringent, following the principle of safek deorayisa
lchumrah(18). Thus it is proper to follow the more stringent measurements
for the k'zayis. [Sick and elderly people may rely on the lenient size of a
k'zayis, which is about half of the standard amount.]
But as explained earlier, the Biblical obligation is to eat only one
k'zayis. That one k'zayis should be reckoned according to the maximum
standard, as it is a Biblical requirement. But the second k'zayis, the one
that is eaten to satisfy the concern of the poskim regarding the technical
details of the mitzvah, is not Biblically mandated. For that second k'zayis
we can surely rely upon the smaller, more lenient size. Indeed, some
poskim(19) maintain that one need eat only one large k'zayis to meet all
requirements: The Biblical obligation will be met with the large k'zayis;
the technical details obligation will also be satisfied with the one large
k'zayis, since a large k'zayis can contain two small portions of k'zayis.
There are several methods for estimating the size of one large k'zayis:
About 2/3 of a standard machine matzah; about 24 grams (0.8 oz.) of hand
matzah(20); about the space of a loosely-extended palm (including the
fingers and the thumb) of an average person(21).
Note: Matzah that remains on the gums is counted towards the k'zayis, but
whatever gets stuck between the teeth does not. Burned matzah, or matzah
that is not actually ingested because it has fallen out of one's mouth while
eating, do not count towards the k'zayis either.
The above discussion applies to the matzah eaten at the end of the meal,
the afikoman, as well. There, too, one k'zayis is required(22) while the
second k'zayis is only recommended(23) and anyone who finds it difficult to
eat two portions should eat only one(24). By eating one large k'zayis, one
will surely meet all of his requirements.
1 Outside of Eretz Yisroel, there is a Rabbinic obligation on the second
night as well.
2 Mishnah Berurah 475:9 and 41, based on Magen Avraham and Shulchan Aruch
Harav. But other poskim rule that this is not required; see Eliyahu Rabbah
475:2 and 12; Aruch ha-Shulchan 4, Dinim v'Hanhagos 17:34 quoting he custom
of the Chazon Ish; Yechaveh Da'as 1:17.
3 Most people find this difficult to do - Moadim u'Zmanim 3:259, especially
if they use a large piece for a k'zayis.
4 Igros Moshe O.C. 4:41. Some poskim allow only two minutes while others
allow up to four minutes. [If, mistakenly, one took longer than four minutes
to eat his portion, he should eat another k'zayis, but without reciting the
5 The time begins from the beginning of the swallowing, not from the
beginning of the chewing; Kol Dodi 14:7.
7 Based on the rule of aiyn osin mitzvos chavilos chavilos.
8 As the Chasam Sofer is quoted: This mitzvah (eating matzah on Pesach) is
the only Biblical mitzvah of "eating" that has remained for us to fulfill in
these times when the bais ha-mikdash is not standing... it is proper to
fulfill it in a manner which satisfies all opinions l'chatchillah... (Vayged
9 When the first blessing - ha-motzi - is recited, all three matzos should
be held so that lechem mishneh can be fulfilled.
10 Mishnah Berurah 475:3. Other poskim do not insist that they be broken
together; see Shulchan Aruch ha-rav 475:5.
11 The two portions cannot be eaten separately, since we are unsure which is
the "correct" one. Eating one before the other could create questions of
hefsek between the "correct" blessing and the "correct" k'zayis.
12 See Orchos Rabbeinu 2:66 that this was the custom of the Chazon Ish and
Harav Y.Y. Kanievsky. This is also the common practice.
13. See Beiur Halachah who questions the basis for this practice and its
14 Chazon Ish is quoted by several sources as ruling that there is no need
to eat more than one k'zayis, and this was the custom of the Chazon Ish
himself; see Orchos Rabbeinu 2:70.
15 Harav S.Y. Elyashiv (quoted in Seder ha-Haruch 79:4); Hagadas Moadim
u'Zmanim, pg. 97; Kol Dodi 14:3. See also Shemiras Shabbos K'hilchasah 55
note 15 quoting Harav S.Z. Auerbach. [Igros Moshe O.C. 5:16 recommends that
each male household member have in front of him three matzos, so that
everyone should have enough matzah for two portions of k'zayis.]
17 O.C. 475:1 and Mishnah Berurah 10. He should recline when eating both
18 Mishnah Berurah 486:1.
19 Seder Pesach K'hilchaso 8:4, quoting Harav S.Y. Elyashiv and Harav N.
20 It is difficult to estimate the size of a k'zayis of a hand matzah, since
the matzos vary in size and in thickness. Generally, a little more than a
quarter of an average matzah is a large k'zayis; Piskei Teshuvos 486:1.
21 Halaylah ha-Zaeh, pg. 19. Chazon Ish and Harav Y.Y. Kanivesky measured
the large k'zayis as the space of their loosley-extended palm without the
thumb; Orchos Rabbeinu 2:66.
22 According to most opinions, the obligation is Rabbinical in nature.
23 Mishnah Berurah 477:1
24 Shulchan Aruch Harav 477:3. Some poskim maintain that women and children
are only obligated to eat one k'zayis for afikoman; see Seder ha-Haruch