How much dough is one to separate:[1] Lechatchila, the custom is to separate one Kezayis ] of dough. If one separated less than this amount it is nevertheless valid. ____________________________________ [1] Rama 322:5 [2] Following the ruling of Rav Avraham Chaim Naah. However according to the Chazon Ish
How much dough is one to separate:[1] Lechatchila, the custom is to separate one Kezayis [approximately 28 grams[2]] of dough. If one separated less than this amount it is nevertheless valid.