What Is a Time Dilation Calculator?
A time dilation calculator computes how time slows down for an object moving at high speed, according to Einstein's special theory of relativity. The faster something moves relative to an observer, the slower its time passes from the observer's perspective. Enter a velocity and a time interval, and the calculator returns the dilated time and the Lorentz factor.
How to Use the Calculator
- Enter the velocity (as a fraction of the speed of light or in m/s).
- Enter the proper time interval.
- Calculate — see the dilated time and Lorentz factor.
The Time Dilation Formula
t = t₀ ÷ √(1 − v²/c²)
where t₀ is the proper time (in the moving frame), t is the dilated time (observer's frame), v is the velocity, and c is the speed of light. The factor 1 ÷ √(1 − v²/c²) is the Lorentz factor, often written γ (gamma).
The Lorentz Factor at Various Speeds
| Speed (fraction of c) | Lorentz Factor (γ) |
|---|---|
| 0.1c | ~1.005 |
| 0.5c | ~1.155 |
| 0.9c | ~2.294 |
| 0.99c | ~7.089 |
At everyday speeds the effect is negligible, but as velocity approaches the speed of light, time dilation grows dramatically.
Why Time Dilation Happens
- Speed of light is constant for all observers, which forces time and space to adjust.
- Moving clocks run slow relative to a stationary observer.
- Real evidence: fast-moving particles and precise atomic clocks confirm the effect.
- GPS satellites must account for relativistic time effects to stay accurate.
Frequently Asked Questions
What is time dilation?
Time dilation is the slowing of time for an object moving at high speed relative to an observer, predicted by special relativity.
What is the time dilation formula?
t = t₀ ÷ √(1 − v²/c²), where t₀ is proper time, v is velocity, and c is the speed of light. The factor is the Lorentz factor γ.
What is the Lorentz factor?
The Lorentz factor, γ = 1 ÷ √(1 − v²/c²), measures how much time, length, and mass change at high speeds. It is 1 at rest and grows toward infinity near light speed.
Is time dilation real?
Yes — it is confirmed by experiments with fast particles and atomic clocks, and even GPS satellites must correct for it to remain accurate.
Is this time dilation calculator free?
Yes — it is completely free, requires no signup, and computes dilated time and the Lorentz factor.