Hot work tools are subjected to complex thermal and mechanical loads during hot forming processes. Locally, the stresses can exceed the material's yield strength in highly loaded areas. During mass production, this leads to cyclic plastic deformations and thermomechanical fatigue of the tools, which can be a major lifetime limiting factor. However, established concepts for thermomechanical fatigue life assessment of hot work tools do not exist, since this aspect first reached attention in the last years with the needs for higher resource and energy efficiency as well as optimized manufacturing processes (e. g. in the frame of Industrie 4.0). Hence, in this paper, the contemporary industrially used concepts for dimensioning hot forming tools regarding the tooling fatigue life are presented. Furthermore an overview of existing plasticity and lifetime models is given. The models are divided in phenomenological and mechanism based models. The review shows that further research is essential in this field.