There is a proposal of a method for the profiling the end windows of trochoid rotary machines according to the given geometric parameters for constructing the trochoid and the degree of gas pressure increase. Its area of application is rotary piston engines and trochoid compressors and pumps. Verification of the mathematical model was carried out on the basis of gas flow simulation data in a three-dimensional setting in the AVL Fire software package. The model of the working process of a trochoid machine is based on the fundamental equations of momentum, energy, diffusion and continuity, written in the Reynolds form and supplemented by the k–?–f turbulence model. The developed method makes it possible to estimate quickly the throughput of the windows of a trochoid rotary machine with less computing resources than in a three-dimensional calculation.