Kilometer to Astronomical Unit Converter
Convert Kilometer (km) to Astronomical Unit (AU) instantly. 1 km = 6.684587e-9 AU.
Length Converter
31 units available
1 km = 6.684587e-9 AU
Formula:
AU = km × 6.684587e-9With your value: 1 km = 6.684587e-9 AU
How big is that?
Everyday references on a logarithmic scale, all expressed in kilometer so you can sanity-check the result.
Other Kilometer to Astronomical Unit conversions
Kilometer to Astronomical Unit Conversion Table
| Kilometer (km) | Astronomical Unit (AU) |
|---|---|
| 0.5 | 3.342294e-9 |
| 1 | 6.684587e-9 |
| 2 | 1.336917e-8 |
| 5 | 3.342294e-8 |
| 10 | 6.684587e-8 |
| 15 | 1.002688e-7 |
| 20 | 1.336917e-7 |
| 25 | 1.671147e-7 |
| 50 | 3.342294e-7 |
| 100 | 6.684587e-7 |
| 250 | 1.671147e-6 |
| 500 | 3.342294e-6 |
| 1000 | 6.684587e-6 |
Astronomical Unit to Kilometer Conversion Table
| Astronomical Unit (AU) | Kilometer (km) |
|---|---|
| 0.5 | 74,798,935.35 |
| 1 | 149,597,870.7 |
| 2 | 299,195,741.4 |
| 5 | 747,989,353.5 |
| 10 | 1,495,978,707 |
| 15 | 2,243,968,060.5 |
| 20 | 2,991,957,414 |
| 25 | 3,739,946,767.5 |
| 50 | 7,479,893,535 |
| 100 | 14,959,787,070 |
| 250 | 37,399,467,675 |
| 500 | 74,798,935,350 |
| 1000 | 149,597,870,700 |
Where these values come from
Every factor on this page is traced to the document that defines it. See the full provenance dataset or our methodology.
Kilometer (km)
Length
Traceable to the metre, defined by fixing the speed of light in vacuum at 299 792 458 m/s. Imperial lengths derive from the 1959 international yard (0.9144 m exactly).
Source: BIPM, The International System of Units (SI), 9th edition, 2019 (updated 2024)
Bureau International des Poids et Mesures · Reviewed 2026-07-01
Astronomical Unit (AU)
Length
The astronomical unit is exactly 149 597 870 700 m (IAU Resolution B2, 2012).
Source: IAU Resolution B2 (2012) — definition of the astronomical unit; IAU B2 (2015) nominal values
International Astronomical Union · Reviewed 2026-07-01
How to Convert Kilometer to Astronomical Unit
To convert from Kilometer (km) to Astronomical Unit (AU), multiply the value by 6.684587e-9.
Formula: AU = km × 6.684587e-9
Reverse: km = AU × 149,597,870.7
Step-by-Step Example
- Start with your value in Kilometer. For example: 5 km
- Multiply by the conversion factor: 5 x 6.684587e-9
- The result is: 3.342294e-8 AU
About Kilometer
The kilometer equals 1,000 meters and is the standard unit for measuring distances between geographical locations in most countries.
Fun Fact: The circumference of Earth is approximately 40,075 km.
Common uses: road distances, geography, running.
About Astronomical Unit
The astronomical unit (AU) is defined as exactly 149,597,870,700 metres, close to the mean Earth–Sun distance. It is the natural yardstick for the Solar System.
Common uses: planetary science, orbital mechanics, astronomy.
Frequently Asked Questions
How many Astronomical Unit are in 1 Kilometer?
There are exactly 6.684587e-9 Astronomical Unit in 1 Kilometer. This means the conversion factor from Kilometer to Astronomical Unit is 6.684587e-9.
What is the formula to convert Kilometer to Astronomical Unit?
The formula to convert Kilometer to Astronomical Unit is: AU = km × 6.684587e-9. For example, to convert 10 Kilometer to Astronomical Unit, you would multiply 10 by 6.684587e-9.
What is a Kilometer?
The kilometer equals 1,000 meters and is the standard unit for measuring distances between geographical locations in most countries.
What is a Astronomical Unit?
The astronomical unit (AU) is defined as exactly 149,597,870,700 metres, close to the mean Earth–Sun distance. It is the natural yardstick for the Solar System.
What are the common uses of Kilometer?
The Kilometer is commonly used in road distances, geography, running.
Related Length Conversions
Cite this page
UnitConvertLab. (2026). Kilometer to Astronomical Unit converter. UnitConvertLab. Retrieved from https://unitconvertlab.com/convert/kilometer-to-astronomical_unit