Body surface area calculator
Body surface area by the Mosteller, Du Bois and Haycock formulas.
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This is a reference implementation of a published formula, provided for use by qualified healthcare professionals. It does not diagnose, does not account for the individual circumstances of any patient, and is not a recommendation for treatment. Confirm every result against your own institutional guidance before acting on it. Clinical judgement always takes precedence over a calculator.
About this calculation
Body surface area is used to size chemotherapy, some antimicrobials and fluid regimens. Several formulas are in use and they do not agree, so all three are shown together — if your protocol names one, use that one.
Formula
Mosteller: BSA (m²) = √( height (cm) × weight (kg) ÷ 3600 )
- Source
- Mosteller RD, New England Journal of Medicine (1987)
- Methodology version
- 1.0.0
- Last reviewed
- 2026-10-28
What this does not account for
- The formulas disagree, most noticeably at the extremes of body size. Dose according to the formula your protocol specifies.
- BSA-based dosing assumes a relationship between surface area and drug clearance that does not hold for every agent.
- Several protocols cap BSA, commonly at 2.0 or 2.2 m². No cap is applied here.