Adhesive forces between particles have a major impact on many processes. The calculation of these forces is possible in the case of ideal smooth surfaces. Nevertheless real surfaces are rough which typically leads to decreased forces. Furthermore the forces are distributed over several orders of magnitude. In the presented paper, a new model to calculate the force distributions is developed. The model is based on surface roughness parameters which can be measured by atomic force microscopy. It is valid for van der Waals forces as well as for hydrophobic forces. (C) 2015 Elsevier B.V. All rights reserved.