Spring Force Calculator

Inputs

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Diameter of the spring wire.
mm
Center-to-center across the coil (outside diameter − wire diameter).
mm
Coils that actually deflect (total coils minus the end coils).
Unloaded overall length — used for solid height and the buckling check.
mm
Working compression — used for force and stress at that point.
mm
Sets the shear modulus G and the allowable shear stress.
Sets the inactive end coils and the buckling end-fixity assumption.

Results

Default result
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Force at deflection (F)
12.39 N

2.786 lbf

At the deflection entered above.

Also computed

Spring rate (k) 1.239 N/mm

Spring index (C) Pass 10

Corrected shear stress (τ) Pass 361.2 MPa

Within allowable.

Allowable shear stress 995 MPa

Static limit at this wire size.

Solid height 10 mm

Buckling (slenderness L₀/D) Pass 4

Stable at any deflection.

Force vs DeflectionThe load line uses the computed spring rate up to travel-to-solid; the operating marker is clamped at the available travel.Force vs Deflection0102030400102030operatingDeflection (mm)Force (N)
The load line uses the computed spring rate up to travel-to-solid; the operating marker is clamped at the available travel.
Method notes 3 notes
  • Static load; ignores fatigue, set and stress relaxation.
  • Allowable shear stress is the static torsional limit at this wire size (45% of estimated tensile strength), before set removal.
  • Buckling assumes the ends are seated between parallel flat surfaces.

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