Time Dilation Calculator
Works out how far a moving clock falls behind.
Time for the stationary observer
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Lorentz factor (γ) —
Difference —
Speed —
Reading this —
The formula
t = γ t₀ γ = 1 ÷ √(1 − v²/c²)
t₀ is the proper time on the moving clock, and c is exactly 299,792,458 m/s.
What to watch out for
Everyday speeds give a γ so close to 1 that the effect needs atomic clocks to measure.
Frequently Asked Questions
How much time passes at 90% of light speed?
For every year on the moving clock, 2.294 years pass for a stationary observer.
What is γ at 99%?
7.089.