The crystal size distribution (CSD) measured by laser diffraction technique is obtained by assuming spherical crystals. If crystals are nonspheres, calibration is responsible for the true crystal size, particle number concentration and population density. In this paper, CSD calibration equations have been deduced. It was shown that when shape factors are size-independent, the weight percent of particles is not affected by crystal shape and calibration is just a horizontal shift of measured CSD. Calibration was taken for plate-like crystals of cefazolin sodium and rod-like crystals Of L-threonine. The effect of CSD calibration on crystal growth kinetics has been investigated in L-threonine-water evaporation crystallization system. (c) 2005 Elsevier B.V. All rights reserved.