Light-Year to AU Converter

Enter a distance and direction to convert between light-years and astronomical units.

How to use

  1. Enter your values in the fields above.
  2. Press Calculate to see your result instantly.
  3. Use the Share button to copy a link to your result.

About this calculator

A light-year is the distance light travels in one Julian year, about 9.4607×10¹² km, while an astronomical unit (AU) is the average Earth-Sun distance, roughly 149.6 million km. The two are related by 1 light-year = 63,241.077 AU.

Astronomers reach for AU when describing distances within the solar system — planets, asteroids, spacecraft trajectories — and switch to light-years (or parsecs) once they're talking about interstellar distances, such as the ~4.25 light-years to Proxima Centauri, our nearest star beyond the Sun. This converter is a quick tool for astronomy students, science communicators, and space enthusiasts moving between these two standard distance scales.

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