{
  "entity_type": "unit_conversion_page",
  "id": "square-miles-to-square-km",
  "name": "Square miles to Square kilometers",
  "title": "Square miles to Square kilometers Converter (mi² to km²)",
  "description": "Convert square miles to square kilometers: 1 mi² = 2.58999 km². Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.",
  "quantity": "area",
  "quantity_name": "Area",
  "base_unit": "m2",
  "from_unit": {
    "symbol": "mi2",
    "display": "mi²",
    "name": "square miles",
    "singular": "square mile"
  },
  "to_unit": {
    "symbol": "km2",
    "display": "km²",
    "name": "square kilometers",
    "singular": "square kilometer"
  },
  "linear": true,
  "factor": 2.58998811,
  "inverse_factor": 0.3861021585,
  "formula": "square kilometers = square miles × 2.58998811",
  "reverse_formula": "square miles = square kilometers × 0.3861021585",
  "unit_relation": "1 mi² = 2.58999 km²",
  "examples": [
    {
      "value": 5,
      "result": 12.9499,
      "text": "5 mi² = 12.9499 km²"
    },
    {
      "value": 12.5,
      "result": 32.3749,
      "text": "12.5 mi² = 32.3749 km²"
    },
    {
      "value": 100,
      "result": 258.999,
      "text": "100 mi² = 258.999 km²"
    }
  ],
  "table": [
    {
      "mi2": 1,
      "km2": 2.58999
    },
    {
      "mi2": 2,
      "km2": 5.17998
    },
    {
      "mi2": 3,
      "km2": 7.76996
    },
    {
      "mi2": 4,
      "km2": 10.36
    },
    {
      "mi2": 5,
      "km2": 12.9499
    },
    {
      "mi2": 6,
      "km2": 15.5399
    },
    {
      "mi2": 7,
      "km2": 18.1299
    },
    {
      "mi2": 8,
      "km2": 20.7199
    },
    {
      "mi2": 9,
      "km2": 23.3099
    },
    {
      "mi2": 10,
      "km2": 25.8999
    },
    {
      "mi2": 15,
      "km2": 38.8498
    },
    {
      "mi2": 20,
      "km2": 51.7998
    },
    {
      "mi2": 25,
      "km2": 64.7497
    },
    {
      "mi2": 30,
      "km2": 77.6996
    },
    {
      "mi2": 40,
      "km2": 103.6
    },
    {
      "mi2": 50,
      "km2": 129.499
    },
    {
      "mi2": 75,
      "km2": 194.249
    },
    {
      "mi2": 100,
      "km2": 258.999
    },
    {
      "mi2": 200,
      "km2": 517.998
    },
    {
      "mi2": 250,
      "km2": 647.497
    },
    {
      "mi2": 500,
      "km2": 1294.99
    },
    {
      "mi2": 1000,
      "km2": 2589.99
    }
  ],
  "faq": [
    {
      "q": "How many square kilometers are in one square mile?",
      "a": "1 mi² = 2.58999 km². 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 square miles to square kilometers?",
      "a": "Multiply the value in square miles by 2.58998811: square kilometers = square miles × 2.58998811. For example, 5 mi² = 12.9499 km²."
    },
    {
      "q": "How do I convert square kilometers back to square miles?",
      "a": "Multiply by the inverse factor 0.3861021585 (square miles = square kilometers × 0.3861021585), or use the square kilometers-to-square miles 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=mi2&to_unit=km2",
    "calculator": "https://tttkmbb.com/api/v1/calculate/area?value=5&from_unit=mi2&to_unit=km2",
    "mcp_tool": "convert_units",
    "mcp_arguments": {
      "value": 5,
      "from_unit": "mi2",
      "to_unit": "km2"
    }
  },
  "links": {
    "html": "https://tttkmbb.com/conversion/square-miles-to-square-km",
    "markdown": "https://tttkmbb.com/conversion/square-miles-to-square-km.md",
    "json": "https://tttkmbb.com/conversion/square-miles-to-square-km.json",
    "reverse": "https://tttkmbb.com/conversion/square-km-to-square-miles",
    "quantity_converter": "https://tttkmbb.com/conversion/area",
    "units": "https://tttkmbb.com/api/v1/units?quantity=area"
  },
  "timestamp": "2026-09-24"
}