{
  "entity_type": "unit_conversion_page",
  "id": "km-to-light-years",
  "name": "Kilometers to Light-years",
  "title": "Kilometers to Light-years Converter (km to ly)",
  "description": "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.",
  "quantity": "length",
  "quantity_name": "Length",
  "base_unit": "m",
  "from_unit": {
    "symbol": "km",
    "display": "km",
    "name": "kilometers",
    "singular": "kilometer"
  },
  "to_unit": {
    "symbol": "ly",
    "display": "ly",
    "name": "light-years",
    "singular": "light-year"
  },
  "linear": true,
  "factor": 1.057000834e-13,
  "inverse_factor": 9460730473000,
  "formula": "light-years = kilometers × 1.057000834e-13",
  "reverse_formula": "kilometers = light-years × 9460730473000",
  "unit_relation": "1 km = 1.057e-13 ly",
  "examples": [
    {
      "value": 5,
      "result": 5.285e-13,
      "text": "5 km = 5.285e-13 ly"
    },
    {
      "value": 12.5,
      "result": 1.32125e-12,
      "text": "12.5 km = 1.32125e-12 ly"
    },
    {
      "value": 100,
      "result": 1.057e-11,
      "text": "100 km = 1.057e-11 ly"
    }
  ],
  "table": [
    {
      "km": 1,
      "ly": 1.057e-13
    },
    {
      "km": 2,
      "ly": 2.114e-13
    },
    {
      "km": 3,
      "ly": 3.171e-13
    },
    {
      "km": 4,
      "ly": 4.228e-13
    },
    {
      "km": 5,
      "ly": 5.285e-13
    },
    {
      "km": 6,
      "ly": 6.34201e-13
    },
    {
      "km": 7,
      "ly": 7.39901e-13
    },
    {
      "km": 8,
      "ly": 8.45601e-13
    },
    {
      "km": 9,
      "ly": 9.51301e-13
    },
    {
      "km": 10,
      "ly": 1.057e-12
    },
    {
      "km": 15,
      "ly": 1.5855e-12
    },
    {
      "km": 20,
      "ly": 2.114e-12
    },
    {
      "km": 25,
      "ly": 2.6425e-12
    },
    {
      "km": 30,
      "ly": 3.171e-12
    },
    {
      "km": 40,
      "ly": 4.228e-12
    },
    {
      "km": 50,
      "ly": 5.285e-12
    },
    {
      "km": 75,
      "ly": 7.92751e-12
    },
    {
      "km": 100,
      "ly": 1.057e-11
    },
    {
      "km": 200,
      "ly": 2.114e-11
    },
    {
      "km": 250,
      "ly": 2.6425e-11
    },
    {
      "km": 500,
      "ly": 5.285e-11
    },
    {
      "km": 1000,
      "ly": 1.057e-10
    }
  ],
  "faq": [
    {
      "q": "How many light-years are in one kilometer?",
      "a": "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."
    },
    {
      "q": "What is the formula to convert kilometers to light-years?",
      "a": "Multiply the value in kilometers by 1.057000834e-13: light-years = kilometers × 1.057000834e-13. For example, 5 km = 5.285e-13 ly."
    },
    {
      "q": "How do I convert light-years back to kilometers?",
      "a": "Multiply by the inverse factor 9460730473000 (kilometers = light-years × 9460730473000), or use the light-years-to-kilometers page."
    }
  ],
  "sources": [
    {
      "name": "NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors",
      "url": "https://www.nist.gov/pml/special-publication-811",
      "type": "standard",
      "retrieved_at": "2026-09-24"
    },
    {
      "name": "BIPM – The International System of Units (SI Brochure, 9th edition)",
      "url": "https://www.bipm.org/en/publications/si-brochure",
      "type": "standard",
      "retrieved_at": "2026-09-24"
    },
    {
      "name": "Wikipedia – Conversion of units",
      "url": "https://en.wikipedia.org/wiki/Conversion_of_units",
      "type": "reference",
      "retrieved_at": "2026-09-24"
    }
  ],
  "freshness": {
    "type": "static",
    "max_age_seconds": null,
    "note": "Fixed conversion factors (NIST/BIPM definitions); results never go stale."
  },
  "api": {
    "convert": "https://tttkmbb.com/api/v1/convert?value=5&from_unit=km&to_unit=ly",
    "calculator": "https://tttkmbb.com/api/v1/calculate/length?value=5&from_unit=km&to_unit=ly",
    "mcp_tool": "convert_units",
    "mcp_arguments": {
      "value": 5,
      "from_unit": "km",
      "to_unit": "ly"
    }
  },
  "links": {
    "html": "https://tttkmbb.com/conversion/km-to-light-years",
    "markdown": "https://tttkmbb.com/conversion/km-to-light-years.md",
    "json": "https://tttkmbb.com/conversion/km-to-light-years.json",
    "reverse": "https://tttkmbb.com/conversion/light-years-to-km",
    "quantity_converter": "https://tttkmbb.com/conversion/length",
    "units": "https://tttkmbb.com/api/v1/units?quantity=length"
  },
  "timestamp": "2026-09-24"
}