What is the Astronomical Unit Converter?
Convert astronomical units (AU) to light-years, parsecs, kilometers, meters, and miles with this free astronomical unit converter. Enter any distance in any unit and get instant results across all astronomical scales. Uses the IAU definition of 1 AU = 149,597,870.7 km. Runs entirely in your browser with no signup.
How to use the Astronomical Unit Converter
- Enter a distance value.
- Select the input unit: AU, light-years, parsecs, km, m, or miles.
- View instant conversions to every other unit.
- Use presets like 1 AU, Moon distance, or Proxima Centauri (4.24 ly).
- Copy the full conversion table and steps.
Common use cases
- Converting 1 AU to kilometers for a homework problem
- Finding how many light-years are in 1 parsec
- Expressing the Earth–Moon distance in astronomical units
Frequently asked questions
- What is an astronomical unit (AU)?
- One astronomical unit is the average distance between Earth and the Sun, defined as exactly 149,597,870.7 km by the IAU since 2012.
- How many AU are in a light-year?
- One light-year equals about 63,241 AU. Conversely, 1 AU is roughly 8.3 light-minutes.
- How do you convert AU to parsecs?
- 1 parsec = 206,264.8 AU. Divide AU by 206,265 to get parsecs, or multiply parsecs by 206,265 to get AU.
- How far is the Moon in AU?
- The Moon's average distance from Earth is about 384,400 km, which equals roughly 0.00257 AU — about 1/390 of an AU.
