Spring Calc by a Spring Maker

A JIS-compliant spring design calculator built by Fuse-Seimitsu Spring Co.,Ltd., a Japanese spring manufacturer founded in 1956.

Design calculations for compression, extension, and torsion coil springs — just enter the dimensions and loads, and you're done. Every formula and material value is based on JIS standards (B 2704-1, G 3522, and others), and all sources can be checked anytime in the in-app "Calculation Basis" page.

FEATURES
- Spring rate, deflection, and stress calculation (per JIS B 2704-1)
- Results from dimensions alone — enter loads to add stress and verdict checks
- Static check: uncorrected stress vs. JIS allowable shear stress (80% for service use)
- Fatigue check: life estimate under cyclic loads (10M / 1M / 100k cycles, JIS materials)
- 7 materials: piano wire SWP-A/B, hard steel wire SW-B/C, oil-tempered wire SWOSC-V, stainless SUS304-WPA/WPB (tensile strength uses JIS minimum values per wire-diameter range)
- Custom materials: register special materials such as phosphor bronze, with optional strength data (results clearly marked as user-defined)
- Save calculations with a company / product name and reload them from the History tab
- Material cost estimates: set prices per kg and enter a quantity to see total mass and cost
- N/kgf unit switching for loads (stresses remain in N/mm² per JIS)
- Compression springs: solid-height check, installed length, pitch, aspect ratio, natural frequency, max test load
- Extension springs: initial tension included (JIS empirical formula), loaded length from free length
- Torsion springs: angle presets (45/90/135/180°), force × arm input, individual leg lengths, double torsion with bridge length, coil ID reduction under load, guide rod diameter
- Wire length and mass estimates, spring index validity check
- Japanese / English, iPhone / iPad

BUILT TO BE AN HONEST ENGINEERING TOOL
- All assumptions, sources, and non-evaluated items are stated in the app
- No ads, no tracking SDKs. Your calculation data never leaves your device

For springs outside standard design ranges or special materials (phosphor bronze, SUS316, titanium, Hastelloy(R), Inconel(R), etc.), contact Fuse-Seimitsu Spring directly via the in-app link.