How Long Would It Take to Travel X Light Years?
Enter a distance in light years and choose a speed — get travel time in years, days and hours.
Note: simplified estimate — ignores acceleration, deceleration, and relativistic effects near light speed.
How it works
A light year is the distance light travels in one Julian year — about 9.46 trillion kilometers. We convert your light year distance to kilometers, then divide by your chosen speed to estimate travel time in years, days, and hours.
Examples
Proxima Centauri is about 4.2 light years away — the closest star to our Sun. Try 4.2 ly at 10% of light speed to see an approximate travel time of around 42 years. The Andromeda Galaxy at 2.5 million light years shows just how vast intergalactic distances are.
FAQ
What is a light year?
A light year is a unit of distance — the distance light travels in one year, approximately 9.46 trillion kilometers (5.88 trillion miles).
How long would it take to travel 1 light year?
At 10% of the speed of light, it would take about 10 years. At a typical spacecraft speed of 50,000 km/h, it would take roughly 21,000 years.
How long to travel to Proxima Centauri (4.2 ly)?
At 10% of light speed, approximately 42 years. At current spacecraft speeds, tens of thousands of years.
Does this account for relativity?
No — this is a simplified Newtonian estimate. At speeds close to light, relativistic time dilation would significantly change the experienced travel time.