Accurate prediction of grinding parameters on an industrial scale is crucial in mineral processing due to the high energy costs and inefficiency of grinding systems. Particle size distribution and grindability of materials are fundamental concepts in grinding. Strengthening the existing relationship between these two important concepts will increase the accuracy of grinding parameter predictions. Until now, the concept of grindability has been expressed as a single value in the literature. However, in this study, grindability is presented as a new distribution property based on the idea that different fractions within a material have different grindabilities. Determining the grindability distribution of a material is based on two processes. The first is grinding the material in stages using an AGAT mill to below the standard particle size of the Hardgrove test and determining the different quantities according to the stage sequence. The second is measuring the HGI values of these different quantities. These processes have shown that materials can be classified according to their increasing grindability, which becomes progressively more difficult with increasing pre-grinding stage sequence.