Systems and method for reducing the size of inertial measurement units are disclosed. In one embodiment, an inertial measurement unit assembly comprises: at least one inertial sensor configured to output uncompensated sensor data; an inertial isolator configured to isolate the at least one inertial sensor; an interface adapter, wherein the interface adapter includes at least one calibration alignment pin that is used as a reference point between the at least one inertial sensor, the inertial interface adapter and a vehicle to which the inertial interface adapter is attached. Furthermore, the inertial measurement unit is configured to output the uncompensated sensor data to a processing device located external to the inertial measurement unit.