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 halacha2go.com: