This paper discusses a novel method to validate Sustainable Saturation Operation (SSO) of ferrite inductors in switching power supplies design. SSO is achieved when an inductor operates in partial saturation, with ripple current, power losses and temperature rise fulfilling reliability and efficiency requirements. Achieving inductors SSO permits to reduce the size of power supplies. The method presented in this paper allows the SSO validation of inductors complying with the power supply specifications. A buck converter with Vin= 36V, Vout = 12 V, fs = 450kHz, Iout = [4, 5]A is adopted as reference case study to provide validation to the proposed approach