Body Surface Area Calculator
BSA is used widely in clinical dosing (especially chemotherapy and pediatric drugs), in cardiac index, and in burn-area estimation. Enter your height and weight in metric or imperial and see all five formulas plus their average. The values usually agree to within a few percent — Mosteller is the most common in clinical practice because of its simple square-root form.
- Mosteller (1987)1.818 m²
- Du Bois & Du Bois (1916)1.810 m²
- Haycock (1978)1.826 m²
- Boyd (1935)1.835 m²
- Gehan & George (1970)1.831 m²
BSA is an estimate, not a measurement. Clinical use should follow your institution's dosing protocol.
How to use
- Pick units (metric or imperial).
- Enter height and weight.
- Compare the five formulas — the average is a reasonable cross-check.
Frequently asked questions
- Which formula should I use?
- Mosteller is the default for adult dosing thanks to its simple form (`√((h·w)/3600)`). Du Bois (1916) is the historical reference. Haycock is preferred for infants and children because it was derived from a pediatric sample.
- Is BSA the same as BMI?
- No. BMI is `weight / height²` and aims to characterize body fatness for a given frame. BSA estimates the skin-surface area in m² and is used to scale drugs and physiological measurements proportional to body size.
- Why do the formulas disagree?
- Each was fit on a different (small) dataset. For an average-sized adult they typically agree to within ~5 %; in the extremes (very small children, very large adults) the spread widens. The average across formulas is a reasonable hedge against any single one being biased for your body type.
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