{
  "id": "height",
  "version": "208d564acfb0",
  "status": "published",
  "name": "Height Calculator",
  "question": "What will my child’s adult height be?",
  "summary": "Predicts a child’s adult height from the parents’ heights with Tanner’s mid-parental method: (father + mother + 13 cm) ÷ 2 for a boy, − 13 cm for a girl, ± 8.5 cm.",
  "category": "health",
  "subcategory": "body",
  "url": "https://www.acalculator.org/health/height-calculator",
  "markdown": "https://www.acalculator.org/health/height-calculator.md",
  "kind": "function",
  "method": "Predicted adult height = (father’s height + mother’s height + 13 cm) ÷ 2 for a boy, or − 13 cm for a girl; range ± 8.5 cm.",
  "assumptions": [
    "Men are on average about 13 cm taller than women, so a parent’s height is moved by 13 cm to the child’s sex before averaging.",
    "The range of 8.5 cm either side is Tanner’s target range, about the 3rd to 97th centile for children of these parents.",
    "The parents are the biological parents, and the child grows in good health and nutrition.",
    "This is a rough guide for families, not a medical prediction. A pediatrician can use growth charts and bone age for more."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "sex": {
        "title": "Child’s sex",
        "description": "The child’s sex, which moves the target up or down by 6.5 cm.",
        "type": "string",
        "enum": [
          "male",
          "female"
        ]
      },
      "father": {
        "title": "Father’s height",
        "description": "The biological father’s adult height.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "minimum": 1,
        "maximum": 2.5
      },
      "mother": {
        "title": "Mother’s height",
        "description": "The biological mother’s adult height.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "minimum": 1,
        "maximum": 2.5
      }
    }
  },
  "outputs": {
    "target": {
      "label": "Predicted adult height",
      "description": "The mid-parental target height: (father + mother ± 13 cm) ÷ 2.",
      "format": "quantity",
      "unit": "in"
    },
    "feetInches": {
      "label": "In feet and inches, or metres",
      "description": "The predicted height in feet and inches (US) or in metres (Metric).",
      "format": "quantity",
      "unit": "ft-in"
    },
    "targetCm": {
      "label": "In centimetres",
      "description": "The predicted height in centimetres.",
      "format": "quantity",
      "unit": "cm"
    },
    "low": {
      "label": "Likely range from",
      "description": "The low end of the target range: the prediction − 8.5 cm.",
      "format": "quantity",
      "unit": "in"
    },
    "high": {
      "label": "Likely range up to",
      "description": "The high end of the target range: the prediction + 8.5 cm.",
      "format": "quantity",
      "unit": "in"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "sex": "male",
      "father": 1.778,
      "mother": 1.6256
    },
    "outputs": {
      "target": 1.7668,
      "feetInches": 1.7668,
      "targetCm": 1.7668,
      "low": 1.6818,
      "high": 1.8518
    },
    "text": "The predicted adult height is 69.6 in (5 ft 9.6 in), likely between 66.2 in and 72.9 in."
  },
  "examples": [
    {
      "given": {
        "sex": "male",
        "father": 1.778,
        "mother": 1.6256
      },
      "expect": {
        "target": 1.7668,
        "low": 1.6818,
        "high": 1.8518
      },
      "source": "Tanner et al. 1970 (mid-parental height ± 8.5 cm); hand calculation in content.mdx"
    },
    {
      "given": {
        "sex": "female",
        "father": 1.778,
        "mother": 1.6256
      },
      "expect": {
        "target": 1.6368,
        "low": 1.5518,
        "high": 1.7218
      },
      "source": "Tanner et al. 1970; hand calculation in content.mdx"
    },
    {
      "given": {
        "sex": "female",
        "father": 1.8,
        "mother": 1.65
      },
      "expect": {
        "target": 1.6600000000000001,
        "targetCm": 1.6600000000000001
      },
      "source": "Tanner et al. 1970; hand calculation in content.mdx"
    },
    {
      "given": {
        "sex": "male",
        "father": 1.8796,
        "mother": 1.7018
      },
      "expect": {
        "target": 1.8557,
        "high": 1.9406999999999999
      },
      "source": "Tanner et al. 1970; hand calculation in content.mdx"
    }
  ],
  "sources": [
    "Tanner JM, Goldstein H, Whitehouse RH. Standards for children's height at ages 2-9 years allowing for heights of parents. Arch Dis Child. 1970;45(244):755-762. https://doi.org/10.1136/adc.45.244.755",
    "Harvard Medical School, Home Parenteral Nutrition program. Linear growth: mid-parental height (father + mother ± 13) ÷ 2, citing Tanner 1970. https://hpn.hms.harvard.edu/linear-growth",
    "Centers for Disease Control and Prevention. Growth charts. https://www.cdc.gov/growthcharts/"
  ],
  "related": [
    "bmi"
  ],
  "changelog": [
    {
      "date": "2026-09-28",
      "note": "The feet-and-inches row is a length: feet and inches in US, metres in Metric (it was text in ft and in)."
    }
  ]
}