Spring weight calculator
Calculate the developed wire length and the weight per piece and per thousand of your spring. Essential for material cost, plating and freight.
Formula
Hooks, legs and special ends add wire to the developed length. The calculator uses the real engine, which includes those additions.
Symbols
Worked example
Computed by the same engine as the calculator above, using the form's starting values.
Weight comes from the developed wire length times the cross-section area times the material density.
Weight per thousand is the basis of raw material cost, of surface treatments priced per kilogram, and of freight estimates.
The designer uses exactly this calculation in quotes, together with the per-operation manufacturing cost.
Material moduli and density
| Material | Shear modulus G | Elastic modulus E | Density |
|---|---|---|---|
| Carbon steel (MW) | 11.5 × 10⁶ psi (79.3 GPa) | 29.5 × 10⁶ psi (203.4 GPa) | 7.85 g/cm³ |
| Stainless 302 (SS302) | 10.0 × 10⁶ psi (69.0 GPa) | 28.0 × 10⁶ psi (193.0 GPa) | 7.90 g/cm³ |
| Stainless 17-7 (SS177) | 11.0 × 10⁶ psi (75.8 GPa) | 29.4 × 10⁶ psi (203.0 GPa) | 7.81 g/cm³ |
| Stainless 316 (SS316) | 10.0 × 10⁶ psi (69.0 GPa) | 28.0 × 10⁶ psi (193.0 GPa) | 7.98 g/cm³ |
| Oil tempered MB (OT) | 11.2 × 10⁶ psi (77.2 GPa) | 29.5 × 10⁶ psi (203.4 GPa) | 7.85 g/cm³ |
| Chrome silicon (CS) | 11.2 × 10⁶ psi (77.2 GPa) | 29.5 × 10⁶ psi (203.4 GPa) | 7.85 g/cm³ |
| Hard drawn (HD) | 11.5 × 10⁶ psi (79.3 GPa) | 29.5 × 10⁶ psi (203.4 GPa) | 7.85 g/cm³ |
| Phosphor bronze (PB) | 6.0 × 10⁶ psi (41.4 GPa) | 14.9 × 10⁶ psi (103.0 GPa) | 8.86 g/cm³ |
| Beryllium copper (BC) | 7.0 × 10⁶ psi (48.3 GPa) | 18.6 × 10⁶ psi (128.0 GPa) | 8.25 g/cm³ |
| Chrome vanadium (CV) | 11.2 × 10⁶ psi (77.2 GPa) | 29.5 × 10⁶ psi (203.4 GPa) | 7.85 g/cm³ |
Frequently asked questions
How is the weight of a spring calculated?
Developed wire length times section area times density: m = ρ·(π·d²/4)·Lw. The developed length is approximately π times the mean diameter times the coil count, plus hooks or legs.
What is the density of spring materials?
Spring steels sit around 7.85 g/cm³, stainless grades around 7.9 g/cm³, and copper alloys such as phosphor bronze and beryllium copper between 8.3 and 8.8 g/cm³.
Why does weight per thousand matter in a quote?
Raw material is bought per kilogram and treatments such as zinc plating are also charged per kilogram. Weight per 1000 pieces turns those costs directly into cost per piece.
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