Abstract: An erosion gauge tool for measuring the erosion of a movable contact in a circuit breaker having a stationary contact and movable contact, both of which are sealed in a housing. The movable contact is coupled to a drive insulator. An erosion mark is etched on the housing adjacent to the drive insulator. The erosion gauge tool has a handle, a tab, and a pointer. The tab is adapted to rest on the drive insulator. The pointer is disposed adjacent to erosion mark when said tab is resting on said drive insulator. As the moveable contact erodes, the pointer moves closer to the erosion mark. The erosion gauge is sized to indicate when the moveable contact needs to be replaced, e.g. when the pointer is immediately adjacent to or above the erosion mark.