{
  "id": "bra-size",
  "version": "7da2b6d48ed5",
  "status": "published",
  "name": "Bra Size Calculator",
  "question": "What is my bra size?",
  "summary": "Computes a starting bra size in US and UK sizes from underbust and bust measurements, with one cup letter for each inch the bust is larger than the band.",
  "category": "everyday-life",
  "url": "https://www.acalculator.org/everyday-life/bra-size-calculator",
  "markdown": "https://www.acalculator.org/everyday-life/bra-size-calculator.md",
  "kind": "function",
  "method": "band = underbust in whole inches, up to the next even number (or + 4 if even, + 5 if odd, by the older method); cup = bust in whole inches − band, one letter per inch.",
  "assumptions": [
    "Measurements round to the nearest whole inch, halves up. Centimetres convert at 2.54 cm to the inch first.",
    "US cups: 1 in A, 2 B, 3 C, 4 D, 5 DD, 6 DDD, 7 G, 8 H, 9 I, 10 J, 11 K. UK cups: 5 DD, 6 E, 7 F, 8 FF, 9 G, 10 GG, 11 H. A difference of 0 is AA.",
    "Sizes differ between brands. The result is a starting size to try on, not a fit."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "under": {
        "title": "Underbust",
        "description": "Snug around the rib cage, just under the bust.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "minimum": 0.5,
        "maximum": 1.8
      },
      "bust": {
        "title": "Bust",
        "description": "Loosely around the fullest part of the bust.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "minimum": 0.5,
        "maximum": 1.8
      },
      "method": {
        "title": "Band method",
        "description": "Use the underbust as the band, or the older method that adds 4 or 5 inches.",
        "type": "string",
        "enum": [
          "underbust",
          "plus-four"
        ]
      }
    }
  },
  "outputs": {
    "us": {
      "label": "US size",
      "description": "The US band and cup.",
      "format": "text"
    },
    "uk": {
      "label": "UK size",
      "description": "The UK band and cup (the band is the same as the US band).",
      "format": "text"
    },
    "band": {
      "label": "Band (in)",
      "description": "The US and UK band size in inches.",
      "format": "integer"
    },
    "difference": {
      "label": "Cup difference (in)",
      "description": "The bust, rounded to a whole inch, minus the band.",
      "format": "integer"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "under": 0.8128,
      "bust": 0.9144,
      "method": "underbust"
    },
    "outputs": {
      "us": "32D",
      "uk": "32D",
      "band": 32,
      "difference": 4
    },
    "text": "With a 32 in underbust and a 36 in bust, your starting US size is 32D."
  },
  "examples": [
    {
      "given": {
        "under": 0.8128,
        "bust": 0.9144,
        "method": "underbust"
      },
      "expect": {
        "us": "32D",
        "uk": "32D",
        "band": 32,
        "difference": 4
      },
      "source": "hand calculation in content.mdx: band 32 (even); 36 − 32 = 4 in = D"
    },
    {
      "given": {
        "under": 0.8483599999999999,
        "bust": 1.016,
        "method": "underbust"
      },
      "expect": {
        "us": "34DDD",
        "uk": "34E",
        "band": 34,
        "difference": 6
      },
      "source": "hand calculation in content.mdx: 33.4 rounds to 33, odd, so band 34; 40 − 34 = 6 in = US DDD, UK E"
    },
    {
      "given": {
        "under": 0.7874,
        "bust": 0.9652,
        "method": "plus-four"
      },
      "expect": {
        "us": "36B",
        "band": 36,
        "difference": 2
      },
      "source": "hand calculation in content.mdx: 31 is odd, so 31 + 5 = 36; 38 − 36 = 2 in = B"
    },
    {
      "given": {
        "under": 0.75,
        "bust": 0.9,
        "method": "underbust"
      },
      "expect": {
        "us": "30DD",
        "uk": "30DD",
        "band": 30,
        "difference": 5
      },
      "source": "hand calculation in content.mdx: 75 cm = 29.53 in → 30; 90 cm = 35.43 in → 35; 35 − 30 = 5 in = DD"
    }
  ],
  "sources": [
    "Wikipedia, Bra size: US and UK band and cup conventions (one cup per inch of difference; US DD, DDD, G…; UK DD, E, F, FF, G, GG, H…) and the plus-four band method. https://en.wikipedia.org/wiki/Bra_size",
    "NIST SP 811 (2008), Appendix B: 1 in = 2.54 cm exactly."
  ],
  "related": [],
  "changelog": []
}