How many kilometers are in one astronomical unit?

One astronomical unit equals approximately 149,597,870.7 kilometers, based on the official IAU definition and NIST/BIPM standards.

Why do some converters show 149,600,000 km instead of 149,597,870.7 km?

Some tools round the AU to 149.6 million kilometers for simplicity in everyday calculations; the difference is less than 0.02% and is acceptable for non-scientific use.

Can I convert kilometers back to astronomical units with these tools?

Yes, most of the listed converters support the reverse conversion (km to AU) using the reciprocal factor, typically around 6.68458712 × 10⁻⁹ AU per kilometer.

What precision level should I choose when converting AU to km?

For most users, the default or auto precision is sufficient. If you are doing scientific work, select more decimal places or use a tool that references NIST/BIPM validated factors.

Are these converters free to use?

All tools in this group are free online converters; some may display ads on the page, but no payment is required to perform the conversion.

Length & Distance6 options compared

Astronomical Units to Kilometers Converter

Converts astronomical units (AU) into kilometers, providing an accurate measurement of distance using this dedicated online utility. Users enter their value in AU and select the desired precision level to ensure highly precise conversion results. The tool executes a straightforward calculation workflow, converting the input unit directly into its equivalent measure in kilometers while also...

Editors’ Top PickBased on community votes

Number Convert

numberconvert.com

Convert Au to km instantly. Free online converter with accurate results and clear explanations.

Open Number Convert Read review →

Other OptionsRanked by votes

02
02
UnitConverters.net
unitconverters.net
Dedicated AU↔km converter with input fields for astronomical unit and kilometer values and a conversion table. Includ...
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03
03
Convert LIVE
convertlive.com
Astronomical units to kilometres converter with selectable precision and a conversion workflow for AU → km. The page ...
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04
04
AllUnits
allunits.net
Free online AU to km converter with input field, formula, and a conversion table. It lists common AU-to-km examples a...
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05
05
ConvertReference
convertreference.org
AU to km and km to AU converter with a swap option and selectable decimal places. The page provides conversion factor...
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06
06
IO Tools
iotools.cloud
Astronomical Unit to Kilometer length converter with instant calculations and a quick chart. It supports multiple len...
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Side by side

Astronomical Units to Kilometers Converter options compared

Tool	Best for	Strengths	Limitations
Number Convert numberconvert.com	Quick, accurate AU-to-km conversion	Instant results Clear explanations Straightforward interface	Ads on the page Fewer unit options
UnitConverters.net unitconverters.net	Reference with conversion table	Conversion table Worked examples Conversion factors	Fewer precision controls Basic design
Convert LIVE convertlive.com	Selectable precision and broad unit support	Precision selector Many target units Conversion workflow	Precision selector can be overwhelming Many unit options clutter the page
AllUnits allunits.net	Simple formula and examples	Clear formula (×149600000) Conversion table with common examples FAQs on page	Rounded conversion factor (149600000 vs 149597870.7) No precision selector
ConvertReference convertreference.org	Editorially validated conversion factors	NIST/BIPM validated factors Selectable decimal places Clean display	Fewer community votes Basic converter only
IO Tools iotools.cloud	API and multi-unit conversion	Supports 23+ length units Instant calculations Quick chart	No data yet for AU↔km specific features API key required for advanced use

Buyer's guide

How to choose a astronomical units to kilometers converter

When picking an AU-to-km converter, accuracy of the conversion factor matters most. The astronomical unit is defined as exactly 149597870.7 km, but some tools round to 149600000 km for simplicity. If you need precise scientific work, choose a tool that cites NIST or BIPM standards. For everyday or educational use, a rounded factor is fine. Also consider whether you want a clean single-purpose converter or one that includes a table, examples, or precision controls, and check for ads or clutter that might slow you down.

Questions

Astronomical Units to Kilometers Converter FAQ

How many kilometers are in one astronomical unit?: One astronomical unit equals approximately 149,597,870.7 kilometers, based on the official IAU definition and NIST/BIPM standards.
Why do some converters show 149,600,000 km instead of 149,597,870.7 km?: Some tools round the AU to 149.6 million kilometers for simplicity in everyday calculations; the difference is less than 0.02% and is acceptable for non-scientific use.
Can I convert kilometers back to astronomical units with these tools?: Yes, most of the listed converters support the reverse conversion (km to AU) using the reciprocal factor, typically around 6.68458712 × 10⁻⁹ AU per kilometer.
What precision level should I choose when converting AU to km?: For most users, the default or auto precision is sufficient. If you are doing scientific work, select more decimal places or use a tool that references NIST/BIPM validated factors.
Are these converters free to use?: All tools in this group are free online converters; some may display ads on the page, but no payment is required to perform the conversion.

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