🌀 Spring Rate Calculator
Calculate the spring rate of a helical spring from wire diameter, coil diameter, and coil count.
mm
mm
GPa
Helical Spring Rate
For a helical compression or extension spring made of round wire, the spring rate (stiffness) is k = Gd4 / (8D3n), where G is the material’s shear modulus, d is the wire diameter, D is the mean coil diameter, and n is the number of active coils.
Because the wire diameter is raised to the fourth power, small changes in wire thickness dramatically change stiffness, while stiffness falls off with the cube of coil diameter. This is the standard formula used to design and specify compression and extension springs across mechanical engineering applications.
Last reviewed August 2026