The size of commercial catalyst pellets is distributed over a range of values. The suitability of the normal, log-normal and Weibull distributions to model pellet size variation was judged by three quality-of-fit criteria: the coefficient of determination, Akaike information criterion and Kolmogorov-Smirnov test, respectively. It is concluded that the normal distribution is most appropriate to represent the diameter distribution of the spherical pellets, though the lognormal distribution also gives a satisfactory fit. The Weibull distribution is the best one to represent the length distribution of the catalyst tablets. It is elucidated that a downward tail of the tablet length distribution results from the fluctuating characteristics of feeding for the individual tablets. It is also pointed out that pellet size distributed in a narrow window is beneficial to the industrial application of solid catalysts.