Why does Hooke's law sometimes have a minus sign?

The minus sign marks restoring-force direction. This calculator reports magnitudes for force, stiffness and displacement.

What units does spring constant use?

The SI unit is newtons per meter, but the calculator also supports common scaled units such as and.

Use it as an educational estimate only. Real springs require manufacturer data, travel limits, fatigue limits and safety factors.

Calculate spring force, spring constant, displacement, elastic potential energy, spring load and equivalent spring stiffness.

Typical stiffness examples

Values depend on material, construction, and working range.

Deformation

Stiffness

Energy units

Spring force magnitude50 N or 5.099 kgf

Elastic deformation energy2.5 J

Equivalent mass at standard gravity5.099 kg

The line slope equals stiffness. Scalar mode shows only the positive range.

The English intent is a spring solver for force, spring constant and displacement, with energy as a useful adjacent result.

F = k x

F is applied spring force, k spring constant and x displacement from equilibrium.

U = \frac{1}{2} k x^{2}

Elastic potential energy for an ideal linear spring.

Linear spring assumption

Hooke's law applies only while the spring or material remains in its linear elastic range.

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: June 2, 2026

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