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BSA Calculator

Calculate body surface area in square meters from height and weight. The headline result uses the Mosteller formula, with the older Du Bois formula and the Haycock formula alongside for comparison.

Quick examples
ft
in
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BSA (Mosteller)1.88 m²
Du Bois
1.88 m²
Haycock
1.88 m²

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      Formula

      Mosteller: BSA (m²) = √(height (cm) × weight (kg) ÷ 3600)
      Du Bois: BSA = 0.007184 × weight (kg)^0.425 × height (cm)^0.725
      Haycock: BSA = 0.024265 × weight (kg)^0.5378 × height (cm)^0.3964

      How to use it

      1. Enter height in feet and inches or in centimeters.
      2. Enter weight in pounds or kilograms.
      3. Read the body surface area in square meters.

      Worked examples

      175 cm and 70 kg

      BSA (Mosteller)
      1.84 m²
      Du Bois
      1.85 m²
      Haycock
      1.85 m²

      5 ft 4 in and 130 lb

      BSA (Mosteller)
      1.63 m²
      Du Bois
      1.63 m²
      Haycock
      1.64 m²

      What BSA is used for

      Body surface area is used in medicine to scale some drug doses — chemotherapy in particular — and to index measurements such as cardiac output and kidney function to body size. Average adult values are about 1.9 m² for men and 1.6 m² for women.

      Mosteller’s 1987 formula is popular because it is simple enough for a pocket calculator and agrees closely with the others for most adults. Du Bois and Du Bois published theirs in 1916 from measurements of just nine people; Haycock’s 1978 formula was validated in infants and children as well as adults. The three typically differ by 1–2% for adults of normal build and by more at the extremes of size.

      Dosing decisions belong with the prescribing clinician and pharmacist. This is an estimate for general information, not medical advice. Talk to a doctor or other qualified clinician before making health decisions based on it.

      Questions people ask

      What is the BSA of someone 175 cm and 70 kg?

      1.84 m² by the Mosteller formula: √(175 × 70 ÷ 3600) = √3.403 = 1.84. Du Bois gives 1.85 m².

      What is a normal body surface area?

      Around 1.9 m² for an average adult man and 1.6 m² for an average adult woman. 1.73 m² is the conventional reference value used to standardize kidney function results.

      Which BSA formula should I use?

      Use whichever your protocol or institution specifies. Mosteller is the most common default today; Du Bois remains in use in many older protocols.

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