Neutron-induced failures in power electronics are a source of concern in many high-reliability applications. This paper describes how to estimate the device’s decreased lifetime expectancy based on its usage. The physical mechanism, Failure in Time (FIT) statistics and FIT rate calculation methodology are presented. Several Microchip SiC MOSFETs and Schottky barrier diodes at different voltage ratings were tested, and the results for the excess FIT rate calculation based on various factors such as operation voltage, altitude, device area, latitude, and duty factor are presented.