Separating Challa from more than 5 lbs. of Dough
After you knead more than 5 lbs. (2.3 kg) of flour at one time:

• Hold part of the dough (at least 1 fl. oz.) while it is still part of the main mass of dough;
• Say the blessing lehafrish challa min ha'isa;
• Separate a small amount (1 fl. oz. is sufficient) of the dough as challa; and
• Say harei zu challa.

Separating Challa from between 2.5 and 5 lbs. of Dough
SITUATION You prepare dough, in a single batch, from more than 2.5 lbs. (1 kg), but less than 5 lbs. (2.3 kg), of flour.
WHAT TO DO Separate a small amount (1 fl. oz. is sufficient) of the dough as “challa.” Don't say the blessing; just say harei zu challa.
NOTE If you mix at least 2.5 lbs. (1 kg) of dough, you must separate challa (without a blessing) even if you will not be baking some of the dough until another time.

Separating Challa from less than 2.5 lbs. of Dough
Don't separate challa if the dough was prepared from less than 2.5 lbs. (1 kg) of flour.