AU to Kilometers Converter

About this calculator

The astronomical unit (AU) is defined as exactly 149,597,870.7 kilometers — roughly the average Earth-Sun distance — and serves as the standard yardstick for measuring distances within our solar system, where expressing everything in kilometers would produce unwieldy numbers.

Mars orbits at about 1.52 AU from the Sun (227.9 million km), and Neptune sits at roughly 30.1 AU (4.5 billion km) — numbers that stay compact and easy to compare in AU but become hard to parse in raw kilometers. This converter switches between the two in either direction with a simple multiplication or division by the fixed 149,597,870.7 km/AU constant.

Astronomy students, science communicators, and space enthusiasts use AU when discussing planetary distances or spacecraft trajectories, then convert to kilometers when a calculation or comparison needs metric units instead.