In this paper the influence of basic design parameters (proportionality coefficient β and permanent magnets height h) on the mechanical torque for cylindrical magnetic coupler with rounded permanent magnets is researched. Such cylindrical magnetic couplers are often used in pumps and liquid mixers. At the beginning the design parameters and their relevance are explained. The mechanical torque is calculated applying the software QuickField. In the data analysis and for the coupler comparison the division of maximal mechanical torque on volume is taken as the main characteristic. Because of the planned optimization for the calculated variants there were synthesized few formulas, from which the most suitable were found (for all researched design parameters’ ranges). The formulas are synthesized using a program, which is created by Oskars Onzevs. The program for the formula synthesis is based on regression models, and the basic principles of it are explained. All the calculations for experimental and formula data are made for magnetic coupler’s design with one pole pair number p that is equal to three.