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
—
DuBois
—
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.