Torsion Spring Calculator

What this calculator does

A torsion spring stores energy by winding rather than by compression. This calculator converts leg position and rotation into torque, checks bending stress in the active coils, and reports the maximum angle before the spring yields or the coils bind.

Inputs and outputs

Inputs

Wire diameter and mean coil diameter
Active coils
Arm length and leg angle
Rotation angle
Winding direction
Material

Results

Torque at the working angle
Angular rate (N·mm/deg)
Bending stress
Maximum recommended rotation
Coil bind check
3D preview

Typical applications

Hinges and lids
Clothespins and clips
Valve handles
Return mechanisms
Agricultural and garden equipment

Design notes

Torsion springs lose torque if the diameter is allowed to shrink during winding. Use a mandrel slightly smaller than the inside diameter and state the wind direction on the drawing; a reversed wind direction changes both torque and stress.

The interactive calculator interface is currently in Chinese. Enter your values there, or send us the load, travel and space constraints and our engineers will return a checked calculation sheet in English.

Frequently asked questions

How is torsion spring torque calculated?

Torque is the product of the angular rate and the rotation from the free position, with the rate derived from wire diameter, mean diameter, active coils and Young’s modulus of the material.

Why does the diameter change when winding?

Winding reduces the coil diameter, which increases stress and torque for the same angle. The calculator accounts for this so the maximum angle is not overestimated.

Can the spring be made with a custom arm?

Yes. Arm length, arm angle and end shape are tooled to the drawing. Send a sketch with the required leg positions and rotation direction.