Hooke's Law Spring Calculator

Hooke's law says an ideal spring's restoring force is directly proportional to how far it's stretched or compressed from its natural length: F = k × x, where k is the spring constant (a measure of stiffness — higher k means a stiffer spring) and x is the displacement from equilibrium. The elastic potential energy stored in that deformation is U = ½ × k × x².

Both formulas are dimensionally self-consistent within either unit system on its own, so no internal metric-to-imperial conversion is needed: with k in newtons per meter and x in meters, force comes out in newtons and energy in joules; with k in pounds-force per foot and x in feet, force comes out in pounds-force and energy in foot-pounds-force (lbf·ft) — a genuine standard unit for mechanical energy, the same one used elsewhere in engineering, not something invented for this calculator.