The breakage probability of different materials can be described well by a single mastercurve comprising the breakage performance of various materials. The function which is obtained when the Weibull statistics is applied to particle breakage depends on the mass-specific impact energy, a minimum energy required to cause any particle fracture at all. the initial particle size and a material parameter which describes the material-specific breakage behaviour. The material parameters are determined by single particle experiments. This procedure under well known stressing conditions gives reproducible result,. A second approach to determine the material parameters from more practicable and less time consuming labscale milling tests is presented. (C) 2004 Elsevier B.V. All rights reserved.