A calibration system includes a housing, a drive shaft within the housing, a load application apparatus operatively connected to the drive shaft to apply a force to the drive shaft, and a plurality of housing transducers operatively connected to the drive shaft to measure at least one of an in-line torque or a prevailing torque of the drive shaft. A method for calibrating a tool includes generating at least one of a pass or fail output from a processing unit based on whether a variance between a prevailing torque from a tool transducer and a prevailing torque from an external tool is within a predetermined variance threshold. A method for measuring prevailing torque in a tool includes determining whether a prevailing torque value is within a predetermined prevailing torque range and adjusting a shut-off threshold torque based on the prevailing torque.