{
  "entity_type": "unit_conversion_page",
  "id": "mm-to-inches",
  "name": "Millimeters to Inches",
  "title": "Millimeters to Inches Converter (mm to in)",
  "description": "Convert millimeters to inches: 1 mm = 0.0393701 in. 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": "mm",
    "display": "mm",
    "name": "millimeters",
    "singular": "millimeter"
  },
  "to_unit": {
    "symbol": "in",
    "display": "in",
    "name": "inches",
    "singular": "inch"
  },
  "linear": true,
  "factor": 0.03937007874,
  "inverse_factor": 25.4,
  "formula": "inches = millimeters × 0.03937007874",
  "reverse_formula": "millimeters = inches × 25.4",
  "unit_relation": "1 mm = 0.0393701 in",
  "examples": [
    {
      "value": 5,
      "result": 0.19685,
      "text": "5 mm = 0.19685 in"
    },
    {
      "value": 12.5,
      "result": 0.492126,
      "text": "12.5 mm = 0.492126 in"
    },
    {
      "value": 100,
      "result": 3.93701,
      "text": "100 mm = 3.93701 in"
    }
  ],
  "table": [
    {
      "mm": 1,
      "in": 0.0393701
    },
    {
      "mm": 2,
      "in": 0.0787402
    },
    {
      "mm": 3,
      "in": 0.11811
    },
    {
      "mm": 4,
      "in": 0.15748
    },
    {
      "mm": 5,
      "in": 0.19685
    },
    {
      "mm": 6,
      "in": 0.23622
    },
    {
      "mm": 7,
      "in": 0.275591
    },
    {
      "mm": 8,
      "in": 0.314961
    },
    {
      "mm": 9,
      "in": 0.354331
    },
    {
      "mm": 10,
      "in": 0.393701
    },
    {
      "mm": 15,
      "in": 0.590551
    },
    {
      "mm": 20,
      "in": 0.787402
    },
    {
      "mm": 25,
      "in": 0.984252
    },
    {
      "mm": 30,
      "in": 1.1811
    },
    {
      "mm": 40,
      "in": 1.5748
    },
    {
      "mm": 50,
      "in": 1.9685
    },
    {
      "mm": 75,
      "in": 2.95276
    },
    {
      "mm": 100,
      "in": 3.93701
    },
    {
      "mm": 200,
      "in": 7.87402
    },
    {
      "mm": 250,
      "in": 9.84252
    },
    {
      "mm": 500,
      "in": 19.685
    },
    {
      "mm": 1000,
      "in": 39.3701
    }
  ],
  "faq": [
    {
      "q": "How many inches are in one millimeter?",
      "a": "1 mm = 0.0393701 in. 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 millimeters to inches?",
      "a": "Multiply the value in millimeters by 0.03937007874: inches = millimeters × 0.03937007874. For example, 5 mm = 0.19685 in."
    },
    {
      "q": "How do I convert inches back to millimeters?",
      "a": "Multiply by the inverse factor 25.4 (millimeters = inches × 25.4), or use the inches-to-millimeters 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=mm&to_unit=in",
    "calculator": "https://tttkmbb.com/api/v1/calculate/length?value=5&from_unit=mm&to_unit=in",
    "mcp_tool": "convert_units",
    "mcp_arguments": {
      "value": 5,
      "from_unit": "mm",
      "to_unit": "in"
    }
  },
  "links": {
    "html": "https://tttkmbb.com/conversion/mm-to-inches",
    "markdown": "https://tttkmbb.com/conversion/mm-to-inches.md",
    "json": "https://tttkmbb.com/conversion/mm-to-inches.json",
    "reverse": "https://tttkmbb.com/conversion/inches-to-mm",
    "quantity_converter": "https://tttkmbb.com/conversion/length",
    "units": "https://tttkmbb.com/api/v1/units?quantity=length"
  },
  "timestamp": "2026-09-24"
}