How many kilometers are in one astronomical unit?

One astronomical unit equals exactly 149,597,870.7 kilometers, the average Earth–Sun distance fixed by the IAU in 2012.

What is an astronomical unit used for?

The AU is a convenient yardstick for distances inside the Solar System — for example Jupiter orbits at about 5.2 AU and Neptune at about 30 AU.

Is my data sent anywhere?

No. The conversion is pure arithmetic that runs entirely in your browser, with no network requests.

Astronomical Unit Converter

Convert astronomical units (AU) to kilometers and back.

Astronomical units to kilometers

The astronomical unit (AU) is the standard yardstick for Solar System distances. One AU is the average distance from Earth to the Sun, defined by the IAU as exactly 149,597,870.7 km.

Type a value in either box — AU or kilometers — and the converter fills in the other side instantly. Everything runs in your browser; nothing is uploaded.