{
  "id": "body-fat",
  "version": "7f08129e20dc",
  "status": "published",
  "name": "Body Fat Calculator",
  "question": "What is my body fat?",
  "summary": "Estimates body fat percentage with the U.S. Navy tape-measure equations or the Deurenberg BMI equation, with fat mass, lean mass, and the ACE category.",
  "category": "health",
  "subcategory": "body",
  "url": "https://www.acalculator.org/health/body-fat-calculator",
  "markdown": "https://www.acalculator.org/health/body-fat-calculator.md",
  "kind": "function",
  "method": "U.S. Navy (DoD), inches: men %BF = 86.010 × log10(waist − neck) − 70.041 × log10(height) + 36.76; women %BF = 163.205 × log10(waist + hip − neck) − 97.684 × log10(height) − 78.387. BMI method (Deurenberg 1991): %BF = 1.20 × BMI + 0.23 × age − 10.8 × sex − 5.4 (sex 1 for men, 0 for women).",
  "assumptions": [
    "The Navy equations take circumferences and height in inches; the calculator converts centimetres first (1 in = 2.54 cm).",
    "Categories are the American Council on Exercise (ACE) ranges, lower bound inclusive.",
    "The equations are for adults. They estimate body fat; lab methods such as DEXA measure it."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "method": {
        "title": "Method",
        "description": "The equation used: U.S. Navy tape measurements, or BMI with age and sex.",
        "type": "string",
        "enum": [
          "navy",
          "bmi"
        ]
      },
      "sex": {
        "title": "Sex",
        "description": "Sex at birth, which the body formulas use.",
        "type": "string",
        "enum": [
          "male",
          "female"
        ]
      },
      "age": {
        "title": "Age",
        "description": "Your age in whole years. Only the BMI method uses it.",
        "type": "integer",
        "minimum": 1,
        "maximum": 120
      },
      "height": {
        "title": "Height",
        "description": "Your height without shoes.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "minimum": 0.5,
        "maximum": 3
      },
      "bodyWeight": {
        "title": "Weight",
        "description": "Your body weight, for fat mass and lean mass (and BMI in the BMI method).",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "exclusiveMinimum": 0,
        "maximum": 700
      },
      "waistCirc": {
        "title": "Waist",
        "description": "Waist circumference: at the navel for men, at the narrowest point for women.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 3
      },
      "neckCirc": {
        "title": "Neck",
        "description": "Neck circumference, just below the larynx (Adam’s apple).",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 3
      },
      "hipCirc": {
        "title": "Hip",
        "description": "Hip circumference at the widest point. Women only.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "exclusiveMinimum": 0,
        "maximum": 3
      }
    }
  },
  "outputs": {
    "bodyFat": {
      "label": "Body fat",
      "description": "Estimated body fat as a percent of body weight.",
      "format": "percent"
    },
    "category": {
      "label": "ACE category",
      "description": "The American Council on Exercise category for this body fat percentage and sex.",
      "format": "text"
    },
    "leanShare": {
      "label": "Lean share",
      "description": "Lean body mass as a percent of body weight: 100 − body fat percent.",
      "format": "percent"
    },
    "fatMass": {
      "label": "Fat mass",
      "description": "Body weight × body fat percent.",
      "format": "quantity",
      "unit": "lb"
    },
    "leanMass": {
      "label": "Lean body mass",
      "description": "Body weight minus fat mass.",
      "format": "quantity",
      "unit": "lb"
    },
    "bmi": {
      "label": "BMI",
      "description": "Body mass index, weight in kg ÷ height in m squared (the BMI method uses it).",
      "format": "number"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "method": "navy",
      "sex": "male",
      "age": 30,
      "height": 1.778,
      "bodyWeight": 81.6466266,
      "waistCirc": 0.8128,
      "neckCirc": 0.4064,
      "hipCirc": 1.016
    },
    "outputs": {
      "bodyFat": 11.093847887597526,
      "category": "Athletes",
      "leanShare": 88.90615211240248,
      "fatMass": 9.05775256035874,
      "leanMass": 72.58887403964127,
      "bmi": 25.827045782662992
    },
    "text": "Your estimated body fat is 11.1%, in the ACE Athletes range."
  },
  "examples": [
    {
      "given": {
        "method": "navy",
        "sex": "male",
        "age": 30,
        "height": 1.778,
        "bodyWeight": 81.6466266,
        "waistCirc": 0.8128,
        "neckCirc": 0.4064
      },
      "expect": {
        "bodyFat": 11.093847887597526,
        "category": "Athletes",
        "fatMass": 9.05775256035874
      },
      "source": "DoD / U.S. Navy men: 86.010 × log10(32 − 16) − 70.041 × log10(70) + 36.76 = 11.09% (hand calculation in content.mdx)"
    },
    {
      "given": {
        "method": "navy",
        "sex": "female",
        "age": 30,
        "height": 1.651,
        "bodyWeight": 63.502931800000006,
        "waistCirc": 0.762,
        "neckCirc": 0.3302,
        "hipCirc": 1.016
      },
      "expect": {
        "bodyFat": 31.087927489728287,
        "category": "Average"
      },
      "source": "DoD / U.S. Navy women: 163.205 × log10(30 + 40 − 13) − 97.684 × log10(65) − 78.387 = 31.09% (hand calculation in content.mdx)"
    },
    {
      "given": {
        "method": "navy",
        "sex": "male",
        "age": 40,
        "height": 1.8,
        "bodyWeight": 85,
        "waistCirc": 0.9,
        "neckCirc": 0.4
      },
      "expect": {
        "bodyFat": 18.46207892229652,
        "category": "Average",
        "leanMass": 69.30723291604795
      },
      "source": "DoD / U.S. Navy men with metric tape: 90 cm − 40 cm = 50 cm = 19.685 in, 180 cm = 70.866 in; 86.010 × log10(19.685) − 70.041 × log10(70.866) + 36.76 = 18.46% (hand calculation in content.mdx)"
    },
    {
      "given": {
        "method": "bmi",
        "sex": "male",
        "age": 30,
        "height": 1.778,
        "bodyWeight": 81.6466266
      },
      "expect": {
        "bodyFat": 21.692454939195585,
        "bmi": 25.827045782662992,
        "category": "Average"
      },
      "source": "Deurenberg et al. (1991): 1.20 × BMI 25.83 + 0.23 × 30 − 10.8 × 1 − 5.4 = 21.69% (hand calculation in content.mdx)"
    },
    {
      "given": {
        "method": "bmi",
        "sex": "female",
        "age": 45,
        "height": 1.6,
        "bodyWeight": 64
      },
      "expect": {
        "bodyFat": 34.949999999999996,
        "category": "Obese"
      },
      "source": "Deurenberg et al. (1991): BMI 64 ÷ 1.6² = 25; 1.20 × 25 + 0.23 × 45 − 0 − 5.4 = 34.95% (hand calculation in content.mdx)"
    }
  ],
  "sources": [
    "Hodgdon JA, Beckett MB. Prediction of percent body fat for U.S. Navy men and women from body circumferences and height. Naval Health Research Center, Reports 84-11 and 84-29, San Diego, 1984.",
    "U.S. Army Regulation 600-9, The Army Body Composition Program (DoD circumference equations, in inches).",
    "Deurenberg P, Weststrate JA, Seidell JC. Body mass index as a measure of body fatness: age- and sex-specific prediction formulas. Br J Nutr. 1991;65(2):105-114. https://doi.org/10.1079/bjn19910073",
    "American Council on Exercise, Percent Body Fat Calculator (body fat categories). https://www.acefitness.org/resources/everyone/tools-calculators/percent-body-fat-calculator/"
  ],
  "related": [],
  "changelog": []
}