F = k·x k = F / x · PE_spring = ½·k·x²

Hooke's Law: Spring force, stiffness, extension and stored elastic energy. This free calculator solves for Spring force, constant, extension, energy and shows every step.

The physics

Within a spring's elastic limit, the restoring force is proportional to displacement and points back toward equilibrium (hence the minus sign). The stored energy is the area under the force–extension line, ½kx². Beyond the elastic limit the material deforms permanently and the law breaks down.

Worked example

k = 200 N/m, x = 0.10 m. F = 200·0.10 = 20 N; PE = ½·200·0.10² = 1.0 J.

Common uses

Springs and suspensions, force sensors and scales, materials testing, and the basis of simple harmonic motion.

Frequently asked questions

What is the formula for Hooke's Law?

Hooke's Law uses the formula F = k·x. Spring force, stiffness, extension and stored elastic energy.

How do you calculate Hooke's Law?

Choose which variable to solve for, enter the values you know (in any supported unit), and the calculator substitutes them into F = k·x and shows every step of the working. It can solve for Spring force, constant, extension, energy.

Is the Hooke's Law calculator free to use?

Yes — every Physics Fundamentals calculator is completely free, with no login, no ads and no usage limits.