Thermal deformations can have a significant impact on the mutual arrangement of parts due to different operating temperatures, as well as on their manufacturing from different materials. These circumstances often lead to the occurrence of thermal gaps or tightness in the joints, which must be taken into account at cold assembly of nodes. A screw single-rotor compressor has gaps in its design and the surfaces of the parts forming them are subjected to thermal deformation, therefore, the development of a methodology for calculating the geometric parameters of the screw single-rotor compressor parts, taking into account their thermal deformations, is necessary for the correct operation of the screw single-rotor compressor during its operation. This technique will allow you to assign minimum safe clearances and tolerances to the working bodies of the screw single-rotor compressor at the stage of their manufacture. The article considers the gap between the end surface of the cut-off tooth and the surface of the helical groove of the central rotor screw. On the one hand, the size of the gap under consideration should compensate for the thermal deformation of the parts to protect against jamming. On the other hand, minimizing the gap should ensure the achievement of effective performance indicators of the screw single-rotor compressor, which has the greatest impact on its performance characteristics. The proposed method of numerical simulating the working process in the compressor will allow the most differentiated approach to taking into account the thermal factors affecting the energy performance of the machine.