---
title: Siman 486 – How Much is a K’zayis?
description: "הChelek 5 1. The poskim differ regarding the shiur of k'zayis in relation to an egg. The Shulchan Aruch states that a k'zayis is the volume of half an egg. The Rambam held it is only a third of an…"
url: "https://mishnaberurasummaries.com/docs/siman-486-how-much-is-a-kzayis/"
updated: "2026-07-27"
category: Laws of Pesach – Erev Pesach, Seder Night, Shavuos
---

# Siman 486 – How Much is a K’zayis?

הChelek 5

1. The poskim differ regarding the shiur of k'zayis in relation to an egg. The Shulchan Aruch states that a k'zayis is the volume of half an egg. The Rambam held it is only a third of an egg. For a mitzva d'oraisa like Matza, you should be machmir to eat at least a half of an egg's worth of matza. (MB )

1. Never eat only a third of an egg's worth of food — you are putting yourself into a sofek berachos. Eat either less than a third of an egg's amount, or a half or more which is a kezayis according to all opinions. (MB )

1. There are Achronim who prove that a kezayis nowadays is actually the size of a modern day egg. The Shaaray Teshuva says to be machmir for this for mitzvos d'oraisa. What emerges is that the mitzva to eat the first kezayis of matza amounts to a full egg's worth. (MB ) # **SECTION III — DAAVENING FROM PESACH UNTIL SHAVUOS**

## Key

**ShA**
 : Shulchan Aruch

**MB**
 : Mishna Berura

**ShaH**
 : Shaar Hatsiun

**ShaT**
 : Shaaray Teshuva

**BeH**
 : Beur Halacha

**BaH**
 : Baer Haytayv

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