Unit-To-Unit Distance conversion

Astronomical Units to Kilometres

1 astronomical unit = 149597870.699999988 kilometres

One astronomical unit is 149,597,870.7 km, fixed by definition in 2012 rather than measured. Mars sits between 1.38 and 1.67 AU from the Sun.

Formula km = AU × 149597870.699999988079

=

Type in either field — the other updates on every keystroke. Need other units? Open the full distance converter.

Astronomical Units to Kilometres — quick reference
Astronomical unitKilometre
1 AU149597870.7 km
2 AU299195741.4 km
3 AU448793612.1 km
4 AU598391482.8 km
5 AU747989353.5 km
10 AU1,496,000,000 km
15 AU2243968060.5 km
20 AU2,992,000,000 km
25 AU3739946767.5 km
50 AU7,480,000,000 km
100 AU14,960,000,000 km
500 AU74,800,000,000 km
1000 AU149,600,000,000 km
Kilometres to Astronomical Units — reverse
KilometreAstronomical unit
1 km0 AU
2 km0 AU
3 km0 AU
4 km0 AU
5 km0 AU
10 km0 AU
15 km0 AU
20 km0 AU
25 km0 AU
50 km0 AU
100 km0.000001 AU
500 km0.000003 AU
1000 km0.000007 AU

Worked examples

Common values
SituationFromTo
Mercury0.387 AU57,890,000 km
Venus0.723 AU108,200,000 km
Earth1 AU149,600,000 km
Mars1.524 AU228,000,000 km
Jupiter5.203 AU778,400,000 km
Neptune30.07 AU4,498,000,000 km

Mental-math shortcut

Multiply by 150 million. That uses 1.5 × 10⁸ km per AU, which is only 0.3% high.

Where this conversion comes up

Orbits and spacecraft distances in the solar system are quoted in AU, because kilometre figures become unwieldy. Sunlight takes just over 8 minutes to cross 1 AU.

Common mistakes

Earth is not always exactly 1 AU from the Sun: the distance varies from about 0.983 AU in early January to 1.017 AU in early July. The AU is a fixed length, not the live Earth-Sun distance.

Background

The astronomical unit was based on Earth's orbit until 2012, when the International Astronomical Union fixed it at exactly 149,597,870,700 metres.

Frequently asked

How many kilometres are in a astronomical unit?
1 astronomical unit = 149597870.699999988 kilometres. In the other direction, 1 kilometre = 0.000000007 astronomical units.
What is a astronomical unit?
An astronomical unit is exactly 149,597,870,700 metres, roughly the mean Earth-Sun distance. Planetary orbits are usually quoted in AU.
What is a kilometre?
A kilometre is 1,000 metres, the standard road-distance unit for most of the world.
How many kilometres is one astronomical unit?
One AU is 149,597,870.7 km, usually rounded to 150 million km.

Related distance conversions

Miles to Kilometres Kilometres to Miles Nautical Miles to Kilometres Nautical Miles to Miles Light-Years to Kilometres Metres to Miles