How to Calculate Rotational Torque

Rotational torque measures a force's tendency to rotate an object. To calculate it, you need to know how large the force is and the length between the axis and the point of force application.

Things You'll Need

  • Calculator or computer
  • Convert force to Newtons (N). To convert pounds to Newtons, multiply by 4.45. For example, if force equals 100 lbs.:

    100 * 4.45 = 445 N

    100 lbs. of force is equal to 445 Newtons.

  • Convert length to meters. To convert feet to meters (m), multiply by 0.3. For example, if length equals 2 feet:

    2 * 0.3 = 0.6 meters

    2 feet of length is equal to 0.6 meters.

  • Multiply force by length to calculate torque, which is measured in Newton meters (Nm):

    445 * 0.6 = 267 Nm