How To Calculate Torque For a Gearmotor

To calculate the torque for your gearmotor, you will need to know the motor's horsepower (HP) rating and the gearbox ratio. Once you have these two pieces of information, you can use the following formula:

Torque (lb-ft) = (HP x 5252) / RPM x Gearbox Ratio


  • HP is the horsepower rating of the motor
  • 5252 is a constant
  • RPM is the speed of the motor
  • Gearbox Ratio is the ratio of the output speed to the input speed of the gearbox

For example, let's say you have a gearmotor with a 2 HP motor and a gearbox ratio of 10:1. If the motor is operating at 1800 RPM, you can calculate the torque as follows:

Torque (lb-ft) = (2 x 5252) / 1800 x 10 Torque (lb-ft) = 29.2

Therefore, the torque for this gearmotor is 29.2 lb-ft. It's important to note that this calculation provides an estimate of the torque and may vary based on factors such as motor efficiency and operating environment.