Motor torque (momentum) is one of the motor ratings used to indicate the rotary motor force produced on its output shaft. The motor torque rating is usually captured at the point when the motor is stalled. The torque measurement unit is (Nm) in the metric system or (ft-lbs) in the US system. But the principle is the same torque is a multiplication of lever length (r) and force(F) applied to lever: I=r x F So there is a simple experiment on how to measure motor torque quite accurately without any fancy measuring tools. All you need is a motor of which torque will be measured, a nominal power supply of motor, thread long enough, a mass of known weight, ruler, and a table or other lifted surface where the motor will be fixed.