{
  "id": "shoe-size-converter",
  "version": "2b2b39893ba8",
  "status": "published",
  "name": "Shoe Size Converter",
  "question": "How do I convert my shoe size?",
  "summary": "Converts an adult shoe size between US women's, US men's, UK, and EU sizes and foot length, from the standard size formulas.",
  "category": "convert",
  "subcategory": "units",
  "url": "https://www.acalculator.org/convert/shoe-size",
  "markdown": "https://www.acalculator.org/convert/shoe-size.md",
  "kind": "function",
  "method": "foot length L (mm) from your size; UK = 3 × L ÷ 25.4 − 23; US men’s = UK + 1; US women’s = US men’s + 1½; EU = 3 × L ÷ 20 + 2",
  "assumptions": [
    "Adult sizes only: UK 0 to 20. Children’s sizes use other zero points.",
    "UK sizes count barleycorns (1/3 inch) and EU sizes count Paris points (2/3 cm) of shoe last length. The last is taken as 2 sizes longer than the foot, as in ISO/TS 19407.",
    "US men's = UK + 1. US women's = US men's + 1½ on the common scale, or + 1 on the FIA scale.",
    "Every size is rounded up to the next half size, and Mondopoint up to the next 5 mm, because a shoe a little too big fits and one too small does not.",
    "Brands and countries differ by up to a size. Check the brand’s own chart, or measure your foot and compare foot lengths."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "from": {
        "title": "Size system",
        "description": "The scale your size is in.",
        "type": "string",
        "enum": [
          "us-women",
          "us-men",
          "uk",
          "eu",
          "cm"
        ]
      },
      "size": {
        "title": "Size",
        "description": "Your shoe size on that scale, or your foot length in cm.",
        "type": "number",
        "minimum": 0,
        "maximum": 60
      },
      "scale": {
        "title": "US women's scale",
        "description": "How US women's sizes relate to US men's sizes.",
        "type": "string",
        "enum": [
          "common",
          "fia"
        ]
      }
    }
  },
  "outputs": {
    "converted": {
      "label": "Converted size",
      "description": "The US men's size, or the US women's size when you start from US men's.",
      "format": "text"
    },
    "usMen": {
      "label": "US men's",
      "description": "The US men's size, rounded up to a half size.",
      "format": "number"
    },
    "usWomen": {
      "label": "US women's",
      "description": "The US women's size, rounded up to a half size.",
      "format": "number"
    },
    "uk": {
      "label": "UK",
      "description": "The UK size, rounded up to a half size.",
      "format": "number"
    },
    "eu": {
      "label": "EU",
      "description": "The EU (Paris point) size, rounded up to a half size.",
      "format": "number"
    },
    "footCm": {
      "label": "Foot length (cm)",
      "description": "The foot length the size fits, heel to longest toe.",
      "format": "number"
    },
    "footIn": {
      "label": "Foot length (in)",
      "description": "The same foot length in inches.",
      "format": "number"
    },
    "mondopoint": {
      "label": "Mondopoint (mm)",
      "description": "The ISO 9407 size: foot length in mm, rounded up to 5 mm.",
      "format": "integer"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "from": "us-women",
      "scale": "common",
      "size": 8
    },
    "outputs": {
      "converted": "US men's 6.5",
      "usMen": 6.5,
      "usWomen": 8,
      "uk": 5.5,
      "eu": 38.5,
      "footCm": 24.130000000000003,
      "footIn": 9.500000000000002,
      "mondopoint": 245
    },
    "text": "US women's 8 is US men's 6.5."
  },
  "examples": [
    {
      "given": {
        "from": "us-women",
        "size": 8,
        "scale": "common"
      },
      "expect": {
        "converted": "US men's 6.5",
        "usMen": 6.5,
        "uk": 5.5,
        "eu": 38.5,
        "footCm": 24.13,
        "footIn": 9.5,
        "mondopoint": 245
      },
      "source": "ISO/TS 19407:2015 sizing conversion (https://www.iso.org/standard/62349.html); hand calculation in content.mdx: UK = 8 − 2.5 = 5.5; L = 25.4/3 × 28.5 = 241.3 mm; EU = 0.15 × 241.3 + 2 = 38.195, up to 38.5"
    },
    {
      "given": {
        "from": "us-men",
        "size": 10,
        "scale": "common"
      },
      "expect": {
        "converted": "US women's 11.5",
        "uk": 9,
        "eu": 43,
        "footCm": 27.093333333333334,
        "mondopoint": 275
      },
      "source": "hand calculation in content.mdx: UK 9; L = 25.4/3 × 32 = 270.93 mm; EU = 42.64, up to 43"
    },
    {
      "given": {
        "from": "eu",
        "size": 42,
        "scale": "common"
      },
      "expect": {
        "usMen": 9.5,
        "usWomen": 11,
        "uk": 8.5,
        "eu": 42,
        "footCm": 26.666666666666668,
        "mondopoint": 270
      },
      "source": "hand calculation in content.mdx: L = 20/3 × 40 = 266.67 mm; UK = 3 × 266.67 ÷ 25.4 − 23 = 8.496, up to 8.5"
    },
    {
      "given": {
        "from": "us-women",
        "size": 8,
        "scale": "fia"
      },
      "expect": {
        "usMen": 7,
        "uk": 6,
        "eu": 39,
        "mondopoint": 250
      },
      "source": "hand calculation in content.mdx: FIA scale, UK = 8 − 2 = 6; L = 25.4/3 × 29 = 245.53 mm; EU = 38.83, up to 39"
    },
    {
      "given": {
        "from": "cm",
        "size": 24,
        "scale": "common"
      },
      "expect": {
        "usMen": 6.5,
        "usWomen": 8,
        "uk": 5.5,
        "eu": 38,
        "mondopoint": 240
      },
      "source": "hand calculation in content.mdx: L = 240 mm; UK = 5.35, up to 5.5; EU = 0.15 × 240 + 2 = 38"
    }
  ],
  "sources": [
    "ISO/TS 19407:2015, Footwear — Sizing — Conversion of sizing systems (https://www.iso.org/standard/62349.html): EU = 3/20 × L + 2 and UK = 3/25.4 × L − 23 for foot length L in mm, as quoted in Wikipedia, \"Shoe size\", section \"ISO 19407 and shoe size conversion\". https://en.wikipedia.org/wiki/Shoe_size",
    "Wikipedia, \"Shoe size\", section \"United States\": US men's = 3 × last length (in) − 24, one more than UK; women's sizes are men's plus 1½ (common scale) or plus 1 (FIA scale). https://en.wikipedia.org/wiki/Shoe_size",
    "ISO 9407:2019, Footwear sizing — Mondopoint system of sizing and marking: size is foot length in mm. https://www.iso.org/standard/71594.html"
  ],
  "related": [
    "unit-converter",
    "cm-to-inches",
    "inches-to-cm"
  ],
  "changelog": [
    {
      "date": "2026-09-30",
      "note": "Sizes outside the adult range name that range in the scale you typed."
    }
  ]
}