LIGHT-YEAR TRAVEL CALCULATOR
A light-year is a measure of distance, not time (~9.46 trillion kilometers). Discover how long it would take human technology to journey to our stellar neighbors.
Custom Distance & Speed Inputs
Proxima Centauri
⚡ Relativistic Time Dilation Factor ($\gamma$)
Journey Time Across All Propulsion Modes
Why Interstellar Travel Is So Staggeringly Hard
One light-year is approximately 9,460,730,472,580 kilometers. The fastest spacecraft ever built by humankind—the NASA Parker Solar Probe—reaches peak speeds of nearly 700,000 km/h during solar flybys. Yet even at that blistering speed, it would still take over 6,600 years to reach our nearest stellar neighbor, Proxima Centauri!
Special Relativity reveals that as an object approaches the speed of light, time slows down for the traveler relative to the rest of the Universe ($\gamma = \frac{1}{\sqrt{1 - v^2/c^2}}$). For a hypothetical astronaut traveling at 99.9% the speed of light, a journey across the Milky Way (100,000 light-years) would feel like just 4,470 years on the ship, even though 100,000 years elapsed back on Earth!