Is a light-year a time unit?
No. It is the distance light travels in vacuum during one Julian year.
Light Year Conversion
Convert interstellar distances among light-years, kilometers, miles, and astronomical units.
Convert a light-year distance
Enter a distance and select its current unit.
About this converter
How to use Light Year Conversion, plus the formulas and logic behind the results.
Tool description
A light-year is a unit of distance, not time: it is how far light travels through vacuum in one Julian year.
How to use
- Enter the known distance.
- Choose light-years, kilometers, miles, or AU.
- Select Calculate.
- Review all equivalent astronomical distances.
Formulas & reference
1 ly = 9.4607304725808 × 10¹² kmmiles = kilometers ÷ 1.609344AU = kilometers ÷ 149,597,870.7
Calculation logic
Every input is first converted to kilometers using fixed constants, then converted from kilometers into the other units.
Light Year Conversion FAQ
Common questions about this conversion and how to interpret the result.
How many kilometers are in a light-year?
One light-year is 9,460,730,472,580.8 kilometers.
How many miles are in a light-year?
It is approximately 5.878625 trillion statute miles.
How many AU are in a light-year?
One light-year is approximately 63,241.077 AU.
Why are results so large?
Stellar distances are vastly larger than distances within the Solar System.
Does light travel at the same speed in materials?
No. The light-year uses light speed in vacuum.