What is one astronomical unit?
One AU is exactly 149,597,870.7 kilometers.
Astronomical Unit Calculator
Translate Solar System distances among AU, kilometers, miles, and light-minutes.
Convert astronomical distance
Enter a distance, select its unit, and view all equivalent units.
About this converter
How to use Astronomical Unit Calculator, plus the formulas and logic behind the results.
Tool description
One astronomical unit is exactly 149,597,870.7 kilometers, approximately Earth’s mean distance from the Sun.
How to use
- Enter the known distance.
- Choose AU, kilometers, miles, or light-minutes.
- Select Calculate to normalize the distance to AU.
- Review every equivalent distance.
Formulas & reference
1 AU = 149,597,870.7 kmmiles = kilometers ÷ 1.609344light-minutes = kilometers ÷ 17,987,547.48
Calculation logic
The input is converted to kilometers, then divided by each unit’s kilometer factor. Light-minutes use the exact speed of light.
Astronomical Unit Calculator FAQ
Common questions about this conversion and how to interpret the result.
How many miles are in an AU?
One AU is approximately 92.956 million statute miles.
How many light-minutes is one AU?
Light travels one AU in about 8.31675 minutes.
Is Earth always exactly one AU from the Sun?
No. Earth’s orbit varies; the AU is a fixed reference length.
Can AU measure distances to stars?
It can, but light-years and parsecs are usually more convenient for stellar distances.
Does this use statute miles?
Yes. Miles are international statute miles of exactly 1.609344 km.