Torque from Force Calculator
Torque from a force and its lever arm, or whichever of the three is missing.
Fill any two fields. The empty one is calculated.
How it works
Torque is a force times the distance from the axis at which it acts, measured at right angles to the force:
T = F × r
Worked example. A belt pulls with F = 200 N on a pulley of r = 50 mm →
T = 200 N × 0.05 m = 10 Nm.
Rearranged, F = T / r is the pull a motor torque produces at a pulley, pinion
or drum. Mind that r is the radius, half the diameter.
Unit converters: Nm to lbf·ft, N to lbf, mm to inches.
Questions
How do I calculate torque from force?
T = F × r, where r is the lever arm: the distance from the axis, at right angles to the force. 200 N at 50 mm is 200 × 0.05 = 10 Nm.
How much force does a motor torque produce at a pulley?
F = T / r, with r the pulley radius (half the diameter). 10 Nm on a 50 mm radius pulls with 200 N.
What if the force is not at right angles to the arm?
Only the part of the force at right angles to the arm makes torque: T = F × r × sin θ. Enter that perpendicular part as the force, or the perpendicular distance to the force's line as the radius.