A method to facilitate the scale-up study for batch cooling crystallization using a reactor which has reduced jacket heat transfer area is proposed. It is shown that the thermal behavior of a 30 L or larger reactor can be replicated using a 1 L reactor by blocking a part of the jacket area from the heat transfer to achieve 30 times or larger volume scale-up effect. The proposed method has an additional advantage in that the hydrodynamics are intact and the effects on the thermal behavior can be investigated separately. A usage of the proposed method is demonstrated for seed amount determination in batch cooling crystallization of ammonium sulfate.