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Kilometre to Astronomical unit

Exact answer: 1 km = 6.684587e-9 AE (IAU definition, exact)

Kilometre and Astronomical unit are astronomical lengths. Both are defined by exact constants, not by measurements. Length figures range from nanometres in semiconductor manufacturing to astronomical distances, and inch, foot and mile come from a different system of units.

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From1 km
Result6.684587e-9 AE
Factor1 km = 6.684587e-9 AE
Source basisBIPM SI Brochure · NIST Guide to SI Appendix B

Examples

011 km = 6.684587e-9 AE

Example value from the reference table. Internal calculation uses stored factors; display output is rounded.

02Common mistake

Inch, foot and mile use fixed factors. Errors usually come from early rounding or from mixing land miles and nautical miles.

03Base unit: m

1 km = 1000 m. Then the value is converted through the base unit m into Astronomical unit.

Table

Kilometre to Astronomical unit
KilometreAstronomical unit
16.684587e-9
1,0000.000007
1,000,0000.006685
150,000,0001.002688
1,500,000,00010.026881
10,000,000,00066.845871

Formula

1 km = 1000 m. Then the value is converted through the base unit m into Astronomical unit.

Sources

BIPM SI BrochureSI base units, prefixes and official SI context.NIST Guide to SI Appendix BNIST conversion-factor method and non-SI factors.

Related conversions

Mile to Kilometremi → kmLengthKilometre to Milekm → miLengthNautical mile to Kilometrenmi → kmLengthKilometre to Metrekm → mLength

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Factor origin

Factors come from the stored source family and are not derived from rounded display values.

Rounding rule

UnitCloud keeps calculating with stored factors and rounds only the displayed output by selected precision.

When not to use

Do not use as the sole basis for official, medical, safety-critical or contractual decisions.

Citation

Citation note: UnitCloud, conversion with formula, sources reviewed: September 2026. Length. Source basis: BIPM SI Brochure · NIST Guide to SI Appendix B.

Common questions

What is the factor for Kilometre to Astronomical unit?

1 km = 6.684587e-9 AE

Which formula does Kilometre to Astronomical unit use?

1 km = 1000 m. Then the value is converted through the base unit m into Astronomical unit.

What is the most common mistake?

Inch, foot and mile use fixed factors. Errors usually come from early rounding or from mixing land miles and nautical miles.

When should I verify the result?

Do not use as the sole basis for official, medical, safety-critical or contractual decisions.