Kilometer to Astronomical Unit Converter
Unit Converter
Instant · Precise · Universal
32 units available
6 categories total
How to Convert Kilometer to Astronomical Unit
To convert km to miles: multiply by 0.621371. To convert miles to km: multiply by 1.60934.
1 km = 1,000 m = 100,000 cm = 0.621371 miles. There are 1.60934 km in one mile.
For example, 1 Kilometer (km) = 6.684587e-9 Astronomical Unit (AU).
Kilometer to Astronomical Unit — Common Values
| Kilometer (km) | Astronomical Unit (AU) |
|---|---|
| 0.1 | 6.684587e-10 |
| 0.5 | 3.342294e-9 |
| 1 | 6.684587e-9 |
| 2 | 1.336917e-8 |
| 5 | 3.342294e-8 |
| 10 | 6.684587e-8 |
| 25 | 1.671147e-7 |
| 50 | 3.342294e-7 |
| 100 | 6.684587e-7 |
| 500 | 0.000003342293561 |
| 1000 | 0.000006684587122 |
About Kilometer (km)
Definition
The kilometer is a unit of length equal to 1,000 meters, commonly used to express distances between geographic locations.
Mathematical Relationship
1 km = 1,000 m = 100,000 cm = 0.621371 miles. There are 1.60934 km in one mile.
Conversion Formula
To convert km to miles: multiply by 0.621371. To convert miles to km: multiply by 1.60934.
Practical Applications
Road signs, marathon distances (42.195 km), GPS navigation, geographic mapping, and aviation flight distances.
Interesting Facts
A marathon is 42.195 km. The circumference of Earth is approximately 40,075 km at the equator.
Common Mistakes
Assuming 1 km = 1 mile. A kilometer is only about 62% of a mile. Also, speed: 100 km/h ≈ 62 mph, not 100 mph.
Educational Tips
Quick approximation: multiply km by 0.6 to estimate miles, or multiply miles by 1.6 for km.
About Astronomical Unit (AU)
Definition
The astronomical unit is a unit of length approximating the mean Earth-Sun distance, defined as exactly 149,597,870,700 meters.
Mathematical Relationship
1 AU = 149,597,870,700 m ≈ 149.598 Gm ≈ 499 light-seconds ≈ 8.317 light-minutes.
Conversion Formula
To convert AU to km: multiply by 149,597,870.7. To convert AU to light-years: divide by 63,241.
Practical Applications
Spacecraft mission planning, expressing planetary orbit sizes, and solar system scale models.
Interesting Facts
Light takes about 8 minutes and 20 seconds to travel 1 AU. Mars is about 1.52 AU from the Sun, Jupiter about 5.2 AU.
Common Mistakes
Thinking the AU is the exact Earth-Sun distance — Earth's actual distance varies from ~147 to ~152 Gm over the year due to orbital eccentricity.
Educational Tips
AU makes the solar system manageable: Mercury ≈ 0.39 AU, Venus ≈ 0.72, Earth = 1, Mars ≈ 1.52, Jupiter ≈ 5.2, Saturn ≈ 9.5.