How many AU is 1 kilometer?

One kilometer equals approximately 6.685 x 10-9 AU. One AU is about 149.6 million km.

How many kilometers are in 1 AU?

One AU contains approximately 149,597,871 km (about 149.6 million km).

When is this conversion used?

In space science. Mission distances are reported in km by space agencies, but astronomers prefer AU for solar system scale. Both units coexist in planetary science.

Kilometers to Astronomical Units (km to au) Converter

1 km = 6.68459 × 10⁻⁹ au

1 Kilometer equals 6.68459 × 10⁻⁹ Astronomical Units (1 km = 6.68459 × 10⁻⁹ au). Convert Kilometers to Astronomical Units with formula, table, and examples.

One kilometer equals approximately 6.685 x 10^-9 astronomical units, or about 6.7 billionths of an AU. The Earth-Sun distance (1 AU) is about 149,597,871 km. This conversion is essential in solar system science where distances are given in both units.

How to Convert Kilometers to Astronomical Units

au = km × 6.68459 × 10⁻⁹

Multiply the value in Kilometers by 6.68459 × 10⁻⁹

Take your value in Kilometers
Multiply by 6.68459 × 10⁻⁹
Read the result in Astronomical Units

Common Kilometers to Astronomical Units Conversions

Kilometers (km)	Astronomical Units (au)	Status
1 km	6.68459 × 10⁻⁹ au
5 km	3.34229 × 10⁻⁸ au
10 km	6.68459 × 10⁻⁸ au
42.195 km	2.82056 × 10⁻⁷ au
100 km	6.68459 × 10⁻⁷ au
500 km	0.000003 au
1,000 km	0.000007 au
10,000 km	0.0001 au
100,000 km	0.0007 au
1,000,000 km	0.0067 au
10,000,000 km	0.0668 au
149,597,871 km	1 au

Good to Know About Kilometers to Astronomical Units Conversion

NASA reports spacecraft positions in kilometers. Astronomers discuss planetary positions in AU. The Mars rover team says '225 million km from Earth.' An astronomer says '1.5 AU.' Same distance, different audience, different unit.

Kilometers to Astronomical Units: What You Need to Know

The Earth-Sun distance (1 AU) is 149,597,871 km. Mars at closest approach is about 54.6 million km (0.365 AU). Jupiter is about 628 million km (4.2 AU). When space agencies report mission distances in kilometers, astronomers convert to AU for solar system context.

What is a Kilometer? km

A metric unit of length equal to 1000 meters. The standard unit for measuring road distances and geographic distances in most countries.

Metric road distances geography running

Learn more about Kilometer →

What is a Astronomical Unit? au

Exactly 149,597,870,700 meters by IAU 2012 definition. Roughly the average distance from the Earth to the Sun. Used for distances within our solar system.

Astronomical solar system distances astronomy planetary science

Learn more about Astronomical Unit →

Going the other way? Use our Astronomical Units to Kilometers converter.

Kilometers to Astronomical Units FAQ

One kilometer equals approximately 6.685 x 10^-9 AU. One AU is about 149.6 million km.
One AU contains approximately 149,597,871 km (about 149.6 million km).
In space science. Mission distances are reported in km by space agencies, but astronomers prefer AU for solar system scale. Both units coexist in planetary science.

Non-Frequently Asked Questions About Kilometers to Astronomical Units

Questions nobody should ask - but someone did.

Mars is between 55 and 400 million km from Earth depending on orbital position. At closest approach, it is about 0.37 AU. Your GPS would need a serious software update.