Kilometer to Astronomical unit
Convert Kilometer to Astronomical unit instantly. Free online astronomy unit converter with exact formula, conversion table and FAQ.
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Astronomy Converter
Convert astronomical length, mass, time, and distance units by compatible family.
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Formula
astronomical unit = kilometer × 6.68458712e-9
kilometer = astronomical unit × 1.49597871e+8
Conversion table
| 1 km | 6.68458712e-9 AU |
| 5 km | 3.34229356e-8 AU |
| 10 km | 6.68458712e-8 AU |
| 20 km | 1.33691742e-7 AU |
| 50 km | 3.34229356e-7 AU |
| 100 km | 6.68458712e-7 AU |
| 500 km | 3.34229356e-6 AU |
| 1,000 km | 6.68458712e-6 AU |
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Frequently asked questions
What is the source unit in this conversion?
The source unit is the kilometer (km). A kilometer is a metric unit of length equal to 1,000 meters.
What is the destination unit in this conversion?
The destination unit is the astronomical unit (AU). An astronomical unit (AU) is the mean Earth-Sun distance, about 149.6 million kilometers.
How do I convert kilometer to astronomical unit?
Multiply the kilometer value by 6.68458712e-9. For example, 10 km × 6.68458712e-9 = 6.68458712e-8 AU.
Is the kilometer to astronomical unit conversion exact?
Yes. Both units have a fixed, defined relationship to the astronomy converter's distance base unit, so the conversion factor is exact rather than a measured approximation.
Where is this conversion commonly used?
It's used in astronomy, physics, and space science whenever a distance value expressed in kilometer needs to be compared with, or reported in, astronomical unit.
Can I convert astronomical unit back to kilometer?
Yes. Multiply the astronomical unit value by 1.49597871e+8 to get kilometer.
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About this conversion
This page converts kilometer (km) to astronomical unit (AU) within the astronomy converter.
A kilometer is a metric unit of length equal to 1,000 meters.
An astronomical unit (AU) is the mean Earth-Sun distance, about 149.6 million kilometers.
The formula is astronomical unit = kilometer × 6.68458712e-9, based on each unit's fixed relationship to the astronomy converter's distance base unit.
The conversion is exact, since it relies on a fixed numerical ratio between the two units rather than a measured or approximate value.
Use the calculator above for instant results, or the table below for common kilometer values already converted to astronomical unit.