Kilometers to light-years
Type a value in kilometers to see it in light-years 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 kilometers box.
- Read the result in light-years as you type, and pick the precision you need.
- Swap the direction to convert back, or copy the result.
How it is calculated
ly = km × 1.057000834e-13
Multiply the value in kilometers by 1.057000834e-13 to get light-years.
Example
To convert 25 km to light-years: 25 × 1.057000834e-13 = 2.6425e-12 ly.
Conversion table
| Kilometers (km) | Light-years (ly) |
|---|---|
| 1 | 1.057e-13 |
| 2 | 2.114e-13 |
| 3 | 3.171e-13 |
| 5 | 5.285e-13 |
| 10 | 1.057e-12 |
| 20 | 2.114e-12 |
| 25 | 2.6425e-12 |
| 50 | 5.285e-12 |
| 100 | 1.057e-11 |
| 250 | 2.6425e-11 |
| 500 | 5.285e-11 |
| 1,000 | 1.057e-10 |
About the units
- Kilometer
- A kilometer is exactly 1000 meters and is the usual unit for road and travel distances.
- Light-year
- A light-year is the distance light travels in one Julian year of 365.25 days, exactly 9460730472580800 meters.
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 light-years are in one kilometer?
1 km = 1.057e-13 ly exactly.
How do I convert kilometers to light-years?
Use ly = km × 1.057000834e-13. For example, 25 km = 2.6425e-12 ly.
How many kilometers are in one light-year?
1 ly = 9,460,730,000,000 km.
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.