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Mechanical Engineering Calculators

Spring Rate Calculator

Spring rate from wire and coil dimensions, or from load and deflection, with the force at any travel.

Enter values

Results update as you type.

Result

Spring rate

11.7481 N/mm

In kg/mm
1.19798
In lb/in
67.084
Force at 20 mm
234.96 N
Energy stored at that travel
2.3496 J

About the Spring Rate Calculator

Spring rate from wire and coil dimensions, or from load and deflection, with the force at any travel.

Also known as: spring constant calculator, coil spring rate, n/mm spring, compression spring.

How to use this calculator

  1. Enter calculate from, travel to evaluate and the other fields.
  2. The result updates instantly as you type — press Calculate (or Enter) at any time.
  3. Review the breakdown shown under the main result.
  4. Use Copy result or Share to save the answer or send a link with your inputs.

Formula

k = G·d⁴ / (8·D³·n) · F = k·x

Worked example

Using the values pre-filled in the calculator above:

  • Calculate from: Spring dimensions
  • Wire diameter = 4 mm
  • Mean coil diameter = 30 mm
  • Active coils = 8
  • Shear modulus = 79.3 GPa
  • Travel to evaluate = 20 mm

the calculator returns:

  • Spring rate: 11.7481 N/mm
  • In kg/mm: 1.19798
  • In lb/in: 67.084
  • Force at 20 mm: 234.96 N