Several techniques for analyzing and estimating power losses in insulated-gate bipolar transistors (IGBTs), diodes, MOSFETs, and other power electronics switching devices are known. Most of the approaches in the literature deal with periodic pulse width modulation (PWM) switching schemes. This paper presents a simple analysis tool to estimate these losses under aperiodic switching schemes, e.g. hysteresis. The tool aims to simplify such an analysis with two main measurements-the load current of a converter phase leg and the gate switching waveform of the upper IGBT of that phase. No model estimations, thermal analyses, or slow simulations are required. Consistency between results from the proposed tool and a commercially available tool designed by an IGBT manufacturer is shown. A periodic frequency is proposed to adapt available software used with periodic switching schemes to aperiodic switching schemes. Experimental tests from an inverter application are presented here.