About the Time Dilation Calculator

See exactly how much time slows down for a moving observer, according to special relativity.

What it is

The Time Dilation Calculator applies special relativity's time dilation formula to a chosen velocity (as a fraction of light speed) and elapsed time, computing the Lorentz factor and the corresponding time experienced by a moving observer compared to a stationary one.

Features

Lorentz factor

See ฮณ = 1/โˆš(1 โˆ’ vยฒ/cยฒ) computed precisely for any velocity.

Real-world presets

From the ISS's orbital speed to velocities near light speed.

Adaptive time formatting

Results shown in seconds, minutes, hours, or days as appropriate.

Time-lost readout

See exactly how much time the moving observer "loses" compared to the stationary one.

Ready to use it?

Free, no sign-up required.

Open the Time Dilation Calculator