Kilometers to Astronomical Units (km to AU)
Free online kilometer to astronomical unit converter. Type a value, get an instant exact result — plus the formula, a ready-made conversion table, and reverse conversion.
LENGTH CONVERTER — INSTANT RESULT
Formula: multiply the kilometer value by 6.68459e-09 — i.e. AU = km × 6.68459e-09
Quick check: 1 km = 6.68459e-09 AU
Quick check: 1 km = 6.68459e-09 AU
Kilometers to Astronomical Units conversion table
| Kilometers (km) | Astronomical Units (AU) |
|---|---|
| 1 km | 6.68459e-09 AU |
| 2 km | 1.3369174e-08 AU |
| 3 km | 2.0053761e-08 AU |
| 4 km | 2.6738348e-08 AU |
| 5 km | 3.3422936e-08 AU |
| 6 km | 4.0107523e-08 AU |
| 7 km | 4.679211e-08 AU |
| 8 km | 5.3476697e-08 AU |
| 9 km | 6.0161284e-08 AU |
| 10 km | 6.6845871e-08 AU |
| 15 km | 1.0026881e-07 AU |
| 20 km | 1.3369174e-07 AU |
| 25 km | 1.6711468e-07 AU |
| 30 km | 2.0053761e-07 AU |
| 40 km | 2.6738348e-07 AU |
| 50 km | 3.3422936e-07 AU |
| 75 km | 5.0134403e-07 AU |
| 100 km | 6.6845871e-07 AU |
| 250 km | 1.6711468e-06 AU |
| 500 km | 3.3422936e-06 AU |
| 1,000 km | 6.6845871e-06 AU |
How to convert kilometers to astronomical units
To convert kilometers to astronomical units, multiply the amount in kilometers by 6.68459e-09. For example, 10 km = 6.6845871e-08 AU. To convert in the other direction, divide by the same factor, or use the ⇄ swap button above.
Convert between metric and imperial/US customary length units, plus nautical, astronomical and survey units. The meter is the SI base unit of length; all factors below are exact definitions where a legal definition exists.
Frequently asked questions
How many astronomical units are in one kilometer?
One kilometer is exactly 6.68459e-09 astronomical units.
How do I convert km to AU?
Multiply the km value by 6.68459e-09 to get AU. The converter at the top of this page does this automatically and works in both directions.
How much is 100 kilometers in astronomical units?
100 kilometers equals 6.6845871e-07 astronomical units.