The paper deals about the verification of calculation process of a mutual inductance between two helical coils, whereby backward computation of voltages and currents of designed wireless energy transfer system is serving for confirmation of proposed methodology. Nowadays, there are many mathematical procedures how to compute mutual inductance between two coils. The main approach of proposed paper is exact specification of the formula, which may be used for the determination of the mutual inductance. After mathematical computation were done the confirmation of validity of proposed formula for mutual inductance calculation is verified with simulation as well as with experimental measurement on proposed test bench of wireless energy system. In order to determine the accuracy of investigated computation procedure back- ward confirmation has been provided in the way of comparison of time-waveforms of input/output variables (voltages/currents) from measurement experiment on proposed wireless power transfer (WPT) system with calculated time-waveforms.