Length Contraction Calculator

About this calculator

Length contraction is a consequence of Einstein's special relativity: an object moving at velocity v relative to an observer appears shortened along its direction of motion, following L = L₀·√(1 − β²), where L₀ is the object's rest-frame (proper) length, β = v/c is its speed as a fraction of the speed of light, and the factor √(1 − β²) is the inverse of the Lorentz factor γ. The effect is negligible at everyday speeds but becomes dramatic as v approaches c — at 86.6% of light speed an object appears contracted to half its rest length.

Physics students use this calculator to build intuition for special relativity problems alongside time dilation, particle physicists apply the same Lorentz factor when analyzing particles accelerated to near-light speed in colliders, and science communicators and writers use it to check the numbers behind relativistic scenarios in popular explanations or fiction.