Helical Spring Calculator OFFLINE v3.3

Material properties

Material presets are illustrative, not certified allowable stresses. Check the actual wire grade, diameter, processing, temperature and duty cycle.

Geometry and load Multiple locks supported

Changing one parameter recalculates the others while respecting active locks. Conflicting locks produce a warning. Standard diameter mode locks d automatically.

Stiffness properties Step 2

Spring rate R = G d⁴ / (8 Dm³ n), using the active coil count n and mean diameter Dm. Both spring types use this ideal linear coil-body approximation. For extension springs, preload caused by theoretical L0 below Lc is included; independent manufacturing initial tension and hook deformation are not included. Maximum displacement and energy are theoretical wire-stress-based limits, not verified physical travel or fatigue ratings.

Spring design End configuration

Compression spring solid-length estimate: Lc = (active + inactive end turns) × wire diameter − 0.5 × wire diameter for each ground end. Closed ends use the entered inactive turns. This is a simplified approximation, not a verified end-geometry calculation. For extension springs Lc is the estimated coil-body solid length; hook dimensions are excluded.

Operating forces Step 3

Enter any one of length L, displacement s, or force F for each operating point. For pull springs, s is measured from theoretical L0, and F = R × (L − L0 theoretical), including preload at Lc. The other two values update automatically. Positive s and F indicate loading: compression for push springs and extension for pull springs.

The solid length estimate Lc includes configured inactive compression end turns and grinding allowances; hook geometry is not included. For a real spring, these must be checked separately. Pull spring preload from theoretical L0 below Lc is included; independent manufacturing initial tension is not included.

Left drag to rotate, right drag to pan. Scroll to zoom. Left: physical L0 (Lc when theoretical L0 is shorter); center: adjustable length with its bottom end fixed; right: theoretical limit Ln. Solid 3D swept-wire mesh (WebGL). Extension springs show independently configurable semicircular hooks; grinding uses planar mesh clipping.

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