Time Dilation Calculator

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The time interval measured on the moving clock itself. Choose its unit on the right.
Pick a familiar object to autofill its speed, or keep Custom to type your own.
The speed of the moving frame. Choose the unit on the right.
Dilated time (t)
1.666667 s
Lorentz factor (γ)1.666667
Speed as fraction of c (β)0.8
Extra time elapsed (t − t₀)0.666667 s
Moving clock runs slower by40%
Length contraction (1 m becomes)0.6 m
Distance covered (rest frame)399,723.277333 km
0.8 c
Negligible<0.1Moderate0.1-0.5Large0.5-0.9Extreme0.9+

The Lorentz factor is γ = 1.666667, so the moving clock runs 1.6667× slower.

  • Dilated time follows t = t0 / √(1 − v²/c²) = γ·t0, where c = 299,792,458 m/s.
  • At β = 0.8 of light speed, this is a sizeable effect, the moving clock visibly lags the stationary one.
  • In the same motion, a 1 m rod contracts to 0.6 m and the moving clock runs 40% slower.

Next stepIncrease the velocity toward c and watch gamma climb steeply, the effect is tiny until you near light speed.

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