Body Surface Area Calculator
BSA in m². Used in clinical drug dosing (especially chemotherapy) and as the denominator for cardiac index.
BSA
Average of three formulas
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Mosteller
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DuBois
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Haycock
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Why BSA matters in medicine
Many drugs are dosed per square meter of body surface, not per kilogram, because metabolic rate correlates better with surface area than with weight. Most importantly:
- Chemotherapy — dosed by mg/m² because the therapeutic window is narrow and total body water/distribution matters.
- Cardiac index — cardiac output divided by BSA, lets you compare across body sizes.
- Glomerular filtration rate — standardized to a "normal" BSA of 1.73 m².
Which formula
- Mosteller (1987) — √(height·weight/3600). Simple, accurate for most adults. Most common in modern practice.
- DuBois (1916) — the historical standard. Older fit, slightly less accurate for tall or short patients.
- Haycock (1978) — slightly better than DuBois for infants and children.
For typical adults, the three differ by less than 5%. Clinical practice varies by hospital and specialty.
Estimate — not medical advice
Do not use this figure for drug dosing. Body surface area is used clinically to dose medication including chemotherapy, where the choice of formula and the weight used are deliberate decisions made by a care team. A number from a web page has no place in that calculation.
This is an estimate, not medical advice, and not a diagnosis. It doesn't know your history, your medications, or your other results, and it should never be used to start, stop, or change treatment. If a number here concerns you, take it to a doctor or pharmacist rather than acting on it.