{
  "entity_type": "unit_conversion_page",
  "id": "au-to-km",
  "name": "Astronomical units to Kilometers",
  "title": "Astronomical units to Kilometers Converter (au to km)",
  "description": "Convert astronomical units to kilometers: 1 au = 149598000 km. 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": "au",
    "display": "au",
    "name": "astronomical units",
    "singular": "astronomical unit"
  },
  "to_unit": {
    "symbol": "km",
    "display": "km",
    "name": "kilometers",
    "singular": "kilometer"
  },
  "linear": true,
  "factor": 149597870.7,
  "inverse_factor": 6.684587122e-9,
  "formula": "kilometers = astronomical units × 149597870.7",
  "reverse_formula": "astronomical units = kilometers × 6.684587122e-9",
  "unit_relation": "1 au = 149598000 km",
  "examples": [
    {
      "value": 5,
      "result": 747989000,
      "text": "5 au = 747989000 km"
    },
    {
      "value": 12.5,
      "result": 1869970000,
      "text": "12.5 au = 1869970000 km"
    },
    {
      "value": 100,
      "result": 14959800000,
      "text": "100 au = 14959800000 km"
    }
  ],
  "table": [
    {
      "au": 1,
      "km": 149598000
    },
    {
      "au": 2,
      "km": 299196000
    },
    {
      "au": 3,
      "km": 448794000
    },
    {
      "au": 4,
      "km": 598391000
    },
    {
      "au": 5,
      "km": 747989000
    },
    {
      "au": 6,
      "km": 897587000
    },
    {
      "au": 7,
      "km": 1047190000
    },
    {
      "au": 8,
      "km": 1196780000
    },
    {
      "au": 9,
      "km": 1346380000
    },
    {
      "au": 10,
      "km": 1495980000
    },
    {
      "au": 15,
      "km": 2243970000
    },
    {
      "au": 20,
      "km": 2991960000
    },
    {
      "au": 25,
      "km": 3739950000
    },
    {
      "au": 30,
      "km": 4487940000
    },
    {
      "au": 40,
      "km": 5983910000
    },
    {
      "au": 50,
      "km": 7479890000
    },
    {
      "au": 75,
      "km": 11219800000
    },
    {
      "au": 100,
      "km": 14959800000
    },
    {
      "au": 200,
      "km": 29919600000
    },
    {
      "au": 250,
      "km": 37399500000
    },
    {
      "au": 500,
      "km": 74798900000
    },
    {
      "au": 1000,
      "km": 149598000000
    }
  ],
  "faq": [
    {
      "q": "How many kilometers are in one astronomical unit?",
      "a": "1 au = 149598000 km. 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 astronomical units to kilometers?",
      "a": "Multiply the value in astronomical units by 149597870.7: kilometers = astronomical units × 149597870.7. For example, 5 au = 747989000 km."
    },
    {
      "q": "How do I convert kilometers back to astronomical units?",
      "a": "Multiply by the inverse factor 6.684587122e-9 (astronomical units = kilometers × 6.684587122e-9), or use the kilometers-to-astronomical units 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=au&to_unit=km",
    "calculator": "https://tttkmbb.com/api/v1/calculate/length?value=5&from_unit=au&to_unit=km",
    "mcp_tool": "convert_units",
    "mcp_arguments": {
      "value": 5,
      "from_unit": "au",
      "to_unit": "km"
    }
  },
  "links": {
    "html": "https://tttkmbb.com/conversion/au-to-km",
    "markdown": "https://tttkmbb.com/conversion/au-to-km.md",
    "json": "https://tttkmbb.com/conversion/au-to-km.json",
    "reverse": "https://tttkmbb.com/conversion/km-to-au",
    "quantity_converter": "https://tttkmbb.com/conversion/length",
    "units": "https://tttkmbb.com/api/v1/units?quantity=length"
  },
  "timestamp": "2026-09-24"
}