Engineering lab · Interactive tool
Compression Spring Calculator
Estimate rate, force, corrected shear stress, solid height, and coil-bind margin for a round-wire helical compression spring.
Round-wire compression spring / static screening
Live calculationk = Gd⁴ / 8D³NₐSpring results updated. Spring rate 6.05 newtons per millimeter. Force 72.6 newtons. Coil-bind margin 23 millimeters.
Model, assumptions, and a reproducible reference case
k = Gd⁴/(8D³Nₐ); F = kδ; Hₛ ≈ Nₜd
Reference inputs
Wire 2 mm; mean coil diameter 16 mm; 8 active / 10 total coils; free length 50 mm; deflection 10 mm; G = 79.3 GPa; allowable shear 700 MPa.
- Expected spring rate
- 4.84009 N/mm
- Calculated by this tool
- 4.84009 N/mm
Closed/ground-end solid-height approximation: 20 mm, leaving 20 mm travel margin at the selected deflection. The linear model is rejected at estimated coil bind.
Check the material basis, load cases, and applicable design criteria before using a result. Warning thresholds are prompts for review, not acceptance criteria.
A viable rate still needs a viable spring
The model applies the classical helical-spring rate and Wahl curvature correction. It helps expose geometry, load, stress, and travel tradeoffs early.
Production design must also resolve fatigue, end conditions, free-length variation, set, buckling, surge, relaxation, corrosion, temperature, and supplier process capability.
Before specifying the spring
- Define force targets at every operating position
- Preserve practical clearance before solid height
- Check spring index and manufacturability
- Evaluate fatigue at mean and alternating stress
- Control buckling, guidance, ends, set, and relaxation
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