In many grinding cases, mainly during the last stages of the process, the cumulative particle size distribution is found to follow the Rosin-Rammler equation (RR), the parameters of which can be used as essential criteria to the operation progress. This article presents a method for developing a simplified, easy-to-use process model by utilizing data from laboratory grinding of limestone and clinker and applying some appropriate mathematical transformations to the RR. The proposed simulation model follows the evolution of the particle size range below 200 mum and allows for adequate precision during the last, most energy-consuming grinding stages. These process stages are also the most decisive in de. ning the final product size distribution profile. By applying the model, in laboratory and industrial scale, it is possible to combine the characteristics of the materials of interest and the grinding equipment with the RR parameters, the latter expressed as process-time or energy consumption functions.