Home › Unit Conversion › Kilometers to Light-years
Kilometers to Light-years (km to ly)
Convert kilometers to light-years: 1 km = 1.057e-13 ly. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.
Formula
1 km = 1.057e-13 ly
light-years = kilometers × 1.057000834e-13 — reverse: kilometers = light-years × 9460730473000
The factor is derived from the SI definitions of both units (base unit: m) as listed in NIST SP 811; results on this page are shown to 6 significant figures, the API returns up to 12.
Worked examples
- 5 km = 5.285e-13 ly
- 12.5 km = 1.32125e-12 ly
- 100 km = 1.057e-11 ly
Kilometers to light-years conversion table
| Kilometers (km) | Light-years (ly) |
|---|---|
| 1 | 1.057e-13 |
| 2 | 2.114e-13 |
| 3 | 3.171e-13 |
| 4 | 4.228e-13 |
| 5 | 5.285e-13 |
| 6 | 6.34201e-13 |
| 7 | 7.39901e-13 |
| 8 | 8.45601e-13 |
| 9 | 9.51301e-13 |
| 10 | 1.057e-12 |
| 15 | 1.5855e-12 |
| 20 | 2.114e-12 |
| 25 | 2.6425e-12 |
| 30 | 3.171e-12 |
| 40 | 4.228e-12 |
| 50 | 5.285e-12 |
| 75 | 7.92751e-12 |
| 100 | 1.057e-11 |
| 200 | 2.114e-11 |
| 250 | 2.6425e-11 |
| 500 | 5.285e-11 |
| 1000 | 1.057e-10 |
FAQ
How many light-years are in one kilometer?
1 km = 1.057e-13 ly. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.
What is the formula to convert kilometers to light-years?
Multiply the value in kilometers by 1.057000834e-13: light-years = kilometers × 1.057000834e-13. For example, 5 km = 5.285e-13 ly.
How do I convert light-years back to kilometers?
Multiply by the inverse factor 9460730473000 (kilometers = light-years × 9460730473000), or use the light-years-to-kilometers page.
Related conversions
Machine access
- API:
GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=km&to_unit=ly - MCP: server
https://tttkmbb.com/mcp, toolconvert_unitswith{"value":5,"from_unit":"km","to_unit":"ly"} - Markdown: https://tttkmbb.com/conversion/km-to-light-years.md · JSON: https://tttkmbb.com/conversion/km-to-light-years.json (add
?value=for a result) · Units: /api/v1/units?quantity=length - OpenAPI operationId:
convert_units. Freshness:static. Authentication: none.