Time Dilation Calculator

How it works

Δt = γ · Δt₀ = Δt₀ ÷ √(1 − v²/c²)

A clock moving relative to you ticks slower by the Lorentz factor — this is not an illusion; muons created in the upper atmosphere reach the ground only because their 2.2 µs lifetime is stretched. At 80% of c a one-year voyage measured on board lasts 1.67 years back home. The traveller sees the same distance contracted by the same factor, so both agree on the speed.

Worked example

1 year at 0.8c: γ = 1.667 → 1.667 years pass on Earth; the ship covers 1.33 light-years in Earth’s frame.

Frequently asked questions