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Length Contraction Calculator
Calculate how much an object appears to contract in length when moving at relativistic speeds, according to special relativity.
m
×c
What length contraction is
Length contraction is a prediction of Einstein’s special relativity: an object moving at high speed relative to an observer appears shorter along its direction of motion than its rest length (the length measured when at rest).
The formula
Contracted length L = L0 / γ, where L0 is the rest length and γ = 1/√(1 – v²/c²) is the Lorentz factor, with v/c (beta) being speed as a fraction of light speed. The effect is negligible at everyday speeds but becomes significant as speed approaches the speed of light.
This calculator is for general physics education; it uses the standard special relativity length contraction formula.
Last reviewed August 2026