How Many Grams of Matzah Is a Kezayis at the Seder
Question
How Much Matzah Must One Eat at the Seder? Understanding the Shiur of a Kezayis
Answer
Thank you for your question.
In order to understand how much matzah one needs to eat for the mitzvah of Achilas Matzah on Leil HaSeder, we first need to explain two important machlokesim. One is a machlokes Rishonim, and the second is a machlokes Acharonim. Through these we will understand why different shiurim are given for a kezayis.
The Machlokes Rishonim: How Large Is a Kezayis?
The first machlokes is brought in Tosafos in Eruvin (daf 80) and the Rambam in Hilchos Eruvin (Perek 1). They discuss how large a shiur of a kezayis is in relation to a beitzah.
The Rambam holds that a kezayis is equal to a shlish of a beitzah, meaning one third of an egg. However, Tosafos holds that a kezayis is equal to a chatzi beitzah, half of an egg.
The halachah is that when it comes to a mitzvah d’Oraisa we are stringent and follow the larger shiur, like the opinion of Tosafos that a kezayis is half a beitzah. When it comes to a mitzvah d’Rabbanan we can be lenient and rely on the opinion of the Rambam that a kezayis is only a third of a beitzah.
The Machlokes Acharonim: Did the Measurements Change?
There is another machlokes among the Acharonim regarding whether the olives and eggs of today are the same size as they were in the times of Chazal, or whether they have become smaller over the generations.
Here as well the poskim rule that for a mitzvah d’Oraisa we are stringent and calculate according to the larger measurement, while for a mitzvah d’Rabbanan we may rely on the smaller measurement. This discussion is brought in the Biur Halachah (Siman 271).
According to the more stringent opinion, the volume of a beitzah is approximately 100 cc. According to the more lenient opinion, a beitzah is approximately 50 cc.
Based on this, if we calculate the size of a kezayis according to the opinion that it is half a beitzah, the shiur would come out to about 50 cc. If we follow the opinion that a kezayis is a third of a beitzah, the shiur would be about 33 cc.
Translating the Measurement Into Matzah
When it comes to matzah, the volume of matzah is slightly less than half the equivalent weight of water. Therefore, if we calculate that a kezayis is about 55 cc, the amount of matzah that one needs to eat comes out to approximately 30 grams.
Therefore, the shiur of matzah that one should eat for a kezayis according to the larger shiur is about 30 grams.
This amount of 30 grams is also equal to two kezaysim according to the smaller shiur, since each smaller kezayis would be approximately 15 grams.
The Requirement to Eat Two Kezaysim
Since the halachah is that at the beginning of the Seder, one should eat two kezaysim of matzah, and this Halacha is a din mid’rabbanan, this amount can be fulfilled by eating two smaller kezaysim, which together equal about 30 grams.
However, the requirement to eat two kezaysim applies specifically to the person who recites the brachah, meaning the one who says the brachah of Hamotzi and Al Achilas Matzah.
The other people who listen to the brachah and are yotzei with the brachah of the baal habayis technically only need to eat one kezayis.
Nevertheless, since Achilas Matzah is a mitzvah d’Oraisa, one should be stringent that even the other people at the table eat the larger shiur of a kezayis, which is about 30 grams.
The Shiur for Koreich
However, when it comes to Koreich, since it is a mitzvah d’Rabbanan, one may rely on the smaller shiur and eat approximately 15 grams of matzah.
Halachah Lemaaseh - The Amount of Matzah One Needs to Eat
The Basic Shiur of a Kezayis
So now, halachah lemaaseh, in practice we say as follows. A healthy person, lechatchilah, should eat a kezayis which is approximately 55 cc.
However, as we mentioned earlier, the volume of matzah is a little bit less than half the equivalent weight of water. Therefore, when we translate this measurement into weight, halachah lemaaseh a person needs to eat about 30 grams of matzah.
This amount of 30 grams is considered one kezayis according to the larger shiur, and at the same time it is two kezaysim according to the smaller shiur.
Therefore, both the person who recited the brachah and all the other people sitting around the table should eat about 30 grams of matzah, which fulfills the shiur of a kezayis according to the larger opinion.
How Much Is 30 Grams of Matzah?
Practically speaking, the weight of 30 grams is approximately:
- One square machine matzah, or
- About half of a hand-baked matzah
However, this can vary depending on the bakery. Some bakeries produce larger matzos and some smaller ones. For example, there are bakeries where one kilogram of dough produces 16 matzos, while other bakeries produce around 22 matzos from one kilogram.
Therefore, the exact amount can vary, but generally speaking it comes out to around half a hand-baked matzah.
The Shiur for Afikoman
The same applies to Afikoman, where ideally one should eat two kezaysim.
Therefore, lechatchilah a person should eat:
- One machine matzah, or
- Approximately one full hand-baked matzah
Again, this may vary depending on the size of the matzos of that bakery.
The Shiur for Koreich
When it comes to Koreich, since this mitzvah is derabbanan, one may rely on the smaller shiur.
Therefore, it is enough to eat about 15 grams of matzah, which is approximately:
- Half a machine matzah, or
- About a quarter of a hand-baked matzah.
If It Is Difficult to Eat This Amount
All of the above measurements are lechatchilah.
If it is difficult for someone to eat this amount of matzah, he may be lenient and eat about 17 grams of matzah for the kezayis. This can be relied upon both:
- At the beginning of the meal after washing, and
- For the Afikoman.
The same amount is also sufficient for children who are under the age of bar mitzvah.
When There Is a Medical Concern
If someone has a medical condition and it is forbidden for him to eat even this smaller amount of matzah, then he should consult with a competent halachic authority. Or you can write to us, so that we can determine exactly what shiur he is able to eat.
Wishing you a Chag Kasher v'Sameach.
Source
- Tosafos, Eruvin 80
- Rambam, Hilchos Eruvin 1
- Biur Halachah, Orach Chaim 271
- Azamroh Lishmecho: Moadim, Pesach
