🪐 Astronomical Unit Calculator
Convert distances between astronomical units and kilometers, miles, or light-years for astronomy and physics calculations.
What is an astronomical unit?
An astronomical unit (AU) is defined as exactly 149,597,870.7 kilometers, which is approximately the average distance between Earth and the Sun. It is a convenient unit for describing distances within our solar system.
How this calculator works
Enter a distance value and select which conversion you need. The calculator uses the internationally defined AU value to convert between astronomical units, kilometers, miles, and light-years (1 light-year ≈ 63,241 AU).
- 1 AU = 149,597,870.7 km (exact, by definition)
- 1 AU ≈ 92,955,807 miles
- 1 AU ≈ 0.0000158 light-years
This calculator is designed for educational and general reference purposes in astronomy and physics.
Last reviewed August 2026