Light-years to astronomical units
Type a value in light-years to see it in astronomical units straight away, or type in the second box to convert back.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Type the value in the light-years box.
- Read the result in astronomical units as you type, and pick the precision you need.
- Swap the direction to convert back, or copy the result.
How it is calculated
au = ly × 63,241.07708
Multiply the value in light-years by 63,241.07708 to get astronomical units.
Example
To convert 25 ly to astronomical units: 25 × 63,241.07708 = 1,581,030 au.
Conversion table
| Light-years (ly) | Astronomical units (au) |
|---|---|
| 1 | 63,241.1 |
| 2 | 126,482 |
| 3 | 189,723 |
| 5 | 316,205 |
| 10 | 632,411 |
| 20 | 1,264,820 |
| 25 | 1,581,030 |
| 50 | 3,162,050 |
| 100 | 6,324,110 |
| 250 | 15,810,300 |
| 500 | 31,620,500 |
| 1,000 | 63,241,100 |
About the units
- Light-year
- A light-year is the distance light travels in one Julian year of 365.25 days, exactly 9460730472580800 meters.
- Astronomical unit
- The astronomical unit is exactly 149597870700 meters (IAU 2012), close to the mean Earth to Sun distance.
Limits and caveats
- Results are rounded for display and computed with the browser's floating point precision (about 15 significant digits).
- Both unit factors are exact by their official definitions.
Questions about this tool
How many astronomical units are in one light-year?
1 ly = 63,241.1 au exactly.
How do I convert light-years to astronomical units?
Use au = ly × 63,241.07708. For example, 25 ly = 1,581,030 au.
How many light-years are in one astronomical unit?
1 au = 0.0000158125 ly.
Are the inch, foot and mile factors exact or rounded?
They are exact by definition. Since the 1959 agreement one inch is exactly 2.54 cm, one foot 0.3048 m and one mile 1609.344 m.
What is the difference between a mile and a nautical mile?
A statute mile is 1609.344 meters and is used on roads. A nautical mile is 1852 meters and is used at sea and in aviation.