How does one measure foods to know if it’s a Kazayis



I’m eating some cake or fruit or fish etc., is there a simple way to estimate if it’s a kazayis?



Approximately the size that fits into a small matchbox.

An excellent resource on this matter is the book Halachos of Kezayis by Rabbi Bodner.

For more information, see the following articles on

Article #235: How Much Is a Kezayis? מ”מ

Article #537: What is the correct way to measure a kezayis? מ”מ

Article #724: Sizing up Shiurim: Modern-Day Measuring—Up or Down? מ”מ