Length Contraction Calculator
Calculate how lengths contract at velocities approaching the speed of light.
This tool is for informational and educational purposes only. It is not a substitute for professional financial, medical, legal, or engineering advice. See Terms of Service.
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Request a ToolHow to Use the Length Contraction Calculator
Enter the proper length (the length measured at rest) and the velocity. The calculator shows the contracted length as observed from a stationary frame.
- Enter proper length. This is the length when the object is at rest.
- Enter velocity. The speed of the object relative to the observer.
- Read the result. The contracted length and percentage of contraction appear instantly.
About the Length Contraction Calculator
Length contraction, also called Lorentz contraction, is a relativistic effect where a moving object appears shorter along the direction of motion when observed from a stationary frame. The formula L = L0 * sqrt(1 - v2/c2) shows that at 87% of c, an object is half its rest length. At everyday speeds, the effect is immeasurably small. Length contraction was first proposed by FitzGerald and Lorentz before Einstein provided the theoretical framework in special relativity.
Frequently Asked Questions
Does the object actually get shorter?
From the observer's reference frame, the object truly measures shorter. From the object's own frame, it maintains its proper length. Both perspectives are equally valid in relativity.
At what speed is length halved?
Length is halved at about 86.6% of the speed of light (about 259,628 km/s), where the Lorentz factor equals 2.
Does length contraction happen in all directions?
No. Length contraction occurs only along the direction of motion. Dimensions perpendicular to the motion are unaffected.