Light Year Distance Calculator
Convert between light years, kilometers, miles, astronomical units (AU), parsecs, light seconds, and light minutes. Includes cosmic distance reference table with real star and galaxy distances. Free, instant, no registration.
Cosmic distances
1 light year = 9.461 trillion km = 5.879 trillion miles. Light travels at 299,792.458 km/s.
The light year distance calculator converts between seven astronomical distance units: light years, kilometers, miles, astronomical units (AU), parsecs, light seconds, and light minutes. Enter a value in any unit and see all six other conversions simultaneously — essential for astronomy enthusiasts, students, and science educators.
A light year is the distance light travels in one vacuum year: approximately 9.461 trillion kilometers or 5.879 trillion miles. Light moves at exactly 299,792.458 km per second, making it the universal speed limit. For scale: sunlight takes 8.3 minutes to reach Earth (1 AU), while the nearest star Proxima Centauri is 4.24 light years away — meaning the light you see from it tonight left the star over 4 years ago.
The interactive cosmic distances table lets you click on famous celestial objects — from Proxima Centauri (4.24 ly) to the Andromeda Galaxy (2.5 million ly) — and instantly see the distances in all units. Use this alongside our Unit Converter for terrestrial measurements and Speed Calculator for earthly speed problems.
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