Spring Design Calculator

Design helical compression springs. Calculate spring rate, deflection, shear stress with Wahl correction, and free/solid lengths.

Wire Diameter (d)

Mean Coil Diameter (D)

Active Coils (N)

Shear Modulus (G)

psi

Applied Force (F)

Tab to move between fields

Spring Rate (k)

17.97 lb/in

Deflection

0.56 in

Shear Stress (Wahl)29,153 psi

Solid Length1 in

Estimated Free Length1.64 in

Spring Index (C)10

How to Use This Calculator

Enter the Wire Diameter (d) in inches — common music wire spring sizes range from 0.020" to 0.500".
Enter the Mean Coil Diameter (D) in inches — the average diameter of the spring coils. The spring index C = D/d should be 4–12 for practical springs.
Enter the number of Active Coils (N) that deflect under load. Closed-ground end springs add 2 inactive coils.
Enter the Shear Modulus (G) for the wire material: music wire ≈ 11.5 Mpsi, stainless steel ≈ 10.0 Mpsi.
Enter the Applied Force in lb to calculate deflection and stress at a specific operating load.
Review Spring Rate (lb/in), Deflection (in), Shear Stress (psi with Wahl correction), and estimated Free Length to verify the design fits the installation envelope.

How the result changes with Wire Diameter (d)

Wire Diameter (d): Diameter of the spring wire. Common music wire sizes range from 0.020" to 0.500".
Mean Coil Diameter (D): Average diameter of the coil (OD - wire diameter). Spring index C = D/d should be 4-12 for practical springs.
Active Coils (N): Number of active coils that contribute to deflection. Total coils = active + 2 for closed-ground ends.
Shear Modulus (G): Shear modulus of the wire material. Music wire ≈ 11.5 Mpsi; stainless steel ≈ 10.0 Mpsi; phosphor bronze ≈ 6.0 Mpsi.
Applied Force (F): Force applied to the spring for stress and deflection calculations.

Identify Input Parameters
4 parameters
Wire Diameter (d) = 0.1, Mean Coil Diameter (D) = 1, Active Coils (N) = 8, Shear Modulus (G) = 11500000 = 5 input(s) provided
Calculate Spring Rate
Spring Rate
17.969 = 17.969
Calculate Deflection
Deflection
0.5565 = 0.5565
Calculate Shear Stress
Shear Stress
29153 = 29153
Calculate Solid Length
Solid Length
1 = 1

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