Torque Calculator

How to use the torque calculator

1. Fill in the fields — they start with a worked example.
2. Read the answer, and the arithmetic shown beneath it.
3. Copy the results, or adjust the inputs to compare scenarios.

About this tool

Torque is force times the perpendicular distance to the pivot. Doubling the length of the spanner doubles the torque for the same effort, which is the entire reason long-handled tools exist and why a breaker bar undoes what a socket wrench cannot.

The angle matters and is usually assumed away. Only the component of force perpendicular to the lever produces torque, so pulling at 90 degrees is fully effective while pulling at 30 degrees delivers half — the sine of the angle. Pulling straight along the spanner produces no torque at all, however hard you pull.

Units are the other trap, and this one is specific: pound-feet and foot-pounds are the same measurement written differently, but pound-inches are twelve times smaller and appear on small fasteners and electronics specifications. A bolt torqued to a figure meant as pound-inches using a pound-foot wrench is over-tightened by a factor of twelve, which snaps it.

One clarification worth making: this is the torque a force produces at a distance, which is not the same as the tension it creates in a bolt. The relationship between the two depends on thread pitch, friction and whether the threads are lubricated, and friction typically consumes most of the applied torque — which is why torque figures are specified as dry or lubricated and why the two differ substantially.

Common uses

• Working out the torque a given pull on a spanner produces.
• Finding the lever length needed to reach a target torque.
• Converting a torque specification between metric and imperial units.

Frequently asked questions

How is torque calculated?

Force multiplied by the distance to the pivot, times the sine of the angle between them. At a right angle the sine is one, so torque is simply force times distance.

Are lb-ft and ft-lb the same?

Yes, they are the same measurement written two ways. Pound-inches are different — twelve times smaller — and mixing them up over-tightens a fastener by that factor.

Does torque tell me the tension in a bolt?

Not directly. Most of the applied torque is consumed by friction in the threads and under the head, which is why specifications state whether the threads are dry or lubricated.