Calculate how objects shrink at relativistic speeds.
Velocity & Length
m
%c
Contraction Results
Enter velocity to see the shrinking effect
About this calculator
Quick Reference
L₀Proper length (at rest)
LContracted length (moving)
vVelocity
cSpeed of light
γ1 / √(1 - β²)
Overview
Length contraction is a relativistic effect where a moving object's length is measured to be shorter than its proper length (the length measured in its own rest frame). This only becomes significant as objects approach the speed of light.
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Pro Tips
Length contraction ONLY happens in the direction of motion.
The formula is L = L₀ * √(1 - v²/c²).
The 'Lorentz factor' γ (gamma) describes the magnitude of the effect: L = L₀ / γ.
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Fun Facts
"Wait, did you know that if you could run at 99% the speed of light, you would appear like a flat piece of paper to someone standing still, but you would feel perfectly normal yourself?"
"This isn't just a theory—muons (tiny particles) traveling through Earth's atmosphere 'see' the distance to the ground as being much shorter, which is why they survive long enough to reach us."
"At 100% the speed of light (which is impossible for anything with mass), an object would have zero length in the direction of travel!"
