An electronic trip unit for a circuit interrupter includes a line side voltage sensing module for measuring first voltages on a line side of separable contacts, a load side voltage sensing module for measuring second voltages on a load side of the separable contacts, a current sensor, and a main controller. The main controller is further structured and configured to: (i) for each of a plurality of arc interruption events in the circuit interrupter, determine a mass loss due to contact erosion during the arc interruption event based on one or more of the first voltages, the second voltages and the current measured by the current sensor, (ii) determine a total mass loss based on each determined mass loss due to contact erosion, and (iii) monitor a remaining life of the separable contacts based on the determined total mass loss due to contact erosion.