AbstractSimultaneous population and mass balances have been solved together with a generalized form of nucleation‐growth rate kinetics to obtain the form of crystal size distribution (CSD) for several idealized modes of crystallizer operation, including seed crystal removal, product classification, arbitrary solids concentration, and staged vessels. The effect of holding time and feed supersaturation on crystal size in a mixed suspension, mixed product removal (MSMPR) crystallizer was also studied. A representative CSD from an MSMPR crystallizer plus the relative kinetic order of nucleation to growth rate can be used to predict CSD from any of the above modes of operation.