How to Calculate Rotational Torque

by Ryan Menezes
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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.

Step 1

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.

Step 2

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.

Step 3

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

445 * 0.6 = 267 Nm

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