{
  "id": "bsa",
  "version": "c3cb6988e704",
  "status": "published",
  "name": "BSA Calculator",
  "question": "What is my BSA (body surface area)?",
  "summary": "Calculates body surface area (BSA) in square meters from height and weight with the Mosteller formula and the Du Bois formula.",
  "category": "health",
  "subcategory": "clinical",
  "url": "https://www.acalculator.org/health/bsa-calculator",
  "markdown": "https://www.acalculator.org/health/bsa-calculator.md",
  "kind": "function",
  "method": "Mosteller: BSA (m²) = √(height in cm × weight in kg ÷ 3600). Du Bois: BSA (m²) = 0.007184 × weight^0.425 × height^0.725.",
  "assumptions": [
    "Height in centimeters and weight in kilograms; pounds and feet are converted exactly (1 lb = 0.45359237 kg, 1 in = 2.54 cm).",
    "Each area is rounded to 2 decimals, halves up.",
    "Both formulas estimate the skin area; neither was built for extreme body sizes."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "height": {
        "title": "Height",
        "description": "Height without shoes.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "length",
        "minimum": 0.3,
        "maximum": 2.5
      },
      "weight": {
        "title": "Weight",
        "description": "Body weight.",
        "type": [
          "number",
          "string"
        ],
        "x-quantity": "mass",
        "minimum": 1,
        "maximum": 350
      }
    }
  },
  "outputs": {
    "mosteller": {
      "label": "BSA (Mosteller)",
      "description": "Body surface area by the Mosteller formula, in square meters, to 2 decimals.",
      "format": "number"
    },
    "dubois": {
      "label": "BSA (Du Bois)",
      "description": "Body surface area by the Du Bois formula, in square meters, to 2 decimals.",
      "format": "number"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "height": 1.778,
      "weight": 81.6466266
    },
    "outputs": {
      "mosteller": 2.01,
      "dubois": 2
    },
    "text": "The body surface area is 2.01 m² by the Mosteller formula and 2 m² by the Du Bois formula."
  },
  "examples": [
    {
      "given": {
        "height": 1.7,
        "weight": 70
      },
      "expect": {
        "mosteller": 1.82,
        "dubois": 1.81
      },
      "source": "Mosteller 1987: √(170 × 70 ÷ 3600) = 1.8181; Du Bois 1916: 0.007184 × 70^0.425 × 170^0.725 = 1.8097 (hand calculation in content.mdx, checked with Python 3)"
    },
    {
      "given": {
        "height": 1.778,
        "weight": 81.6466266
      },
      "expect": {
        "mosteller": 2.01,
        "dubois": 2
      },
      "source": "177.8 cm and 81.647 kg: Mosteller √(177.8 × 81.647 ÷ 3600) = 2.0081; Du Bois 1.9959 (hand calculation in content.mdx)"
    },
    {
      "given": {
        "height": 1.1,
        "weight": 18
      },
      "expect": {
        "mosteller": 0.74,
        "dubois": 0.74
      },
      "source": "Mosteller √(110 × 18 ÷ 3600) = 0.7416; Du Bois 0.7411 (hand calculation in content.mdx)"
    },
    {
      "given": {
        "height": 1.6,
        "weight": 50
      },
      "expect": {
        "mosteller": 1.49,
        "dubois": 1.5
      },
      "source": "Mosteller √(160 × 50 ÷ 3600) = 1.4907; Du Bois 1.5011 (hand calculation in content.mdx)"
    }
  ],
  "sources": [
    "Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987;317(17):1098. https://doi.org/10.1056/NEJM198710223171717",
    "Du Bois D, Du Bois EF. Clinical calorimetry: tenth paper. A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med. 1916;XVII(6_2):863-871. https://doi.org/10.1001/archinte.1916.00080130010002",
    "National Institute of Standards and Technology. Guide for the Use of the International System of Units (SI), NIST Special Publication 811, Appendix B (1 lb = 0.45359237 kg, 1 in = 2.54 cm). https://www.nist.gov/pml/special-publication-811"
  ],
  "related": [],
  "changelog": [
    {
      "date": "2026-09-30",
      "note": "Published after this site's editorial review against the cited sources (no clinician review); the page notices say so."
    }
  ]
}