Helical Spring Rate Calculator

Calculate the spring rate (k) for a helical compression spring based on its geometry.

Input Parameters

Wire Diameter (d) (mm)

Mean Coil Diameter (D) (mm)

Number of Active Coils (n)

Shear Modulus (G) (GPa)

Calculation Results

Enter parameters to calculate

About this calculator

Quick Reference

GShear Modulus

dWire diameter

DMean coil diameter

nNumber of active coils

Overview

The spring rate (k) of a helical spring depends on the material properties and the physical dimensions of the coil.

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Pro Tips

The formula is k = (G * d⁴) / (8 * n * D³).
Shear Modulus for steel is typically around 79-80 GPa.
Increasing the wire diameter significantly increases the spring rate (to the 4th power!).

Fun Facts

"The 'active' coils are those that actually compress; usually, the end coils don't contribute to the rate."
"Spring rate is constant for a linear spring, meaning it takes the same amount of extra force to move it each additional millimeter."
"Spring selection in cars is critical for handling; 'progressive' springs have a variable rate."

Formula: k = (G * d⁴) / (8 * n * D³)