Compression Spring Calculator
Enter spring parameters to automatically calculate stiffness, loads at various conditions, and stress verification.
mm
mm
coils
coils
mm
mm
mm
Basic Parameters
Mean Diameter D₂
- mm
Spring Index C = D₂/d
-
Recommended range: 4–14
Wahl Factor K
-
Stiffness & Load
Spring Rate P'
- N/mm
Solid Height
- mm
Installed Preload F₁
- N
Working Load F₂
- N
Solid Load F₃ (Ultimate)
- N
Stress Verification
Installed Stress τ₁
- MPa
Working Stress τ₂
- MPa
Allowable Shear Stress [τ]
- MPa
Conclusion
-
Uncoiled Length
- mm
Helix Angle
- °
Calculation Notes
Spring Rate Formula
P' = Gd⁴ / (8D₂³n)
- G — Shear modulus (~80,000 MPa for spring steel)
- d — Wire diameter
- D₂ — Mean coil diameter = OD − d
- n — Active coils
Stress Check
Shear stress: τ = K × 8FD₂ / (πd³)
K is the Wahl correction factor for inner-side stress concentration.
The design is acceptable when τ₂ < [τ].
Recommended Spring Index
| Wire Dia. d (mm) | Recommended C |
|---|---|
| 0.2–0.4 | 7–14 |
| 0.45–1 | 5–12 |
| 1.1–2.2 | 5–10 |
| 2.5–6 | 4–10 |
| 7–16 | 4–8 |
| 18–24 | 4–6 |
Material Properties
| Material | G (MPa) | [τ] (MPa) |
|---|---|---|
| 50CrVA | 80,000 | 529 |
| 60Si2CrA | 80,000 | 684 |
| 65Mn | 80,000 | 540 |
| 60Si2CrVA | 80,000 | 671 |