Mechanical joining of complex car body components is an essential part of lightweight construction concepts in the field of car body manufacturing. Besides the mechanical behavior of the joints, the influence on the dimensional accuracy is of particular interest, as joining techniques like clinching or self-piercing riveting cause distortion comparable to spot welding. In recent years, a lot of simplified models using the FE-Method to predict the distortion of assemblies caused by welding (weld seams, spot welds) were presented and commercialized. In contrast to thermal joining technologies, there are no such simplified models with practical relevance existing in the mechanical joining technology sector. In this paper, a new method to predict distortion, caused by different mechanical joining technologies, including effects from previous forming processes, and clamping conditions, is presented. The validation of the simplified model takes place due to an extensive design of expe-riments. It can be proved that the distortion of simple as well as of complex specimens can be relia-bly predicted.