Light-Year Converter
A free, browser-based converter. Runs entirely in your browser — no sign up, nothing stored.
Enter Values
How to use this calculator
- Enter a distance in light-years.
- Read it in kilometres, miles, astronomical units (AU) and parsecs.
How it works
The Light-Year Converter turns a distance in light-years into the other units astronomers use. A light-year is the distance light travels in one year — about 9.46 trillion kilometres.
One light-year ≈ 9.4607 × 10¹² km ≈ 5.879 × 10¹² miles ≈ 63,241 AU ≈ 0.3066 parsecs. The converter multiplies your value by each of these constants.
Worked example
Proxima Centauri (4.24 light-years). The nearest star beyond the Sun is 4.24 light-years away — about 4.0 × 10¹³ km, or roughly 1.30 parsecs.
Frequently asked questions
Is a light-year a measure of time?
No — it's a distance. It's how far light travels in a year. The name confuses people because it contains 'year', but it measures length, not time.
What is a parsec?
A parsec is about 3.26 light-years — the distance at which one astronomical unit subtends one arcsecond. Astronomers often use parsecs for distances between stars.
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Tip: Enter any known values to calculate the remaining results.
All calculations run in your browser. Your inputs are never saved or transmitted.