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Clinical — Body Size
Body Surface Area Calculator
Enter height and weight to get body surface area in square metres by the Mosteller and Du Bois formulas.
Body surface area (Mosteller)
—
Square metres of body surface.
| Du Bois BSA | — |
|---|---|
| Height used | — |
| Weight used | — |
Show our math
Enter your figures above to see the step-by-step working.
For clinical reference and education — not a substitute for professional judgmentEverything computed client-side — nothing leaves this page
How the Body Surface Area Calculator Works
Body surface area (BSA) estimates the total surface area of the body and is widely used to dose medications — especially chemotherapy — and to index physiological measurements. This calculator gives the Mosteller estimate, which is simple and the most common, alongside the older Du Bois formula.
Enter height and weight in either metric or imperial units. The Mosteller formula is the square root of height times weight divided by 3600; the Du Bois formula uses fractional powers of height and weight. The two usually agree within a couple of percent.
Mosteller: BSA = √(heightcm × weightkg ÷ 3600)
Frequently Asked Questions
What is body surface area used for?
BSA is used to calculate drug doses (particularly chemotherapy), to index cardiac output and other measurements, and to estimate metabolic needs. It reflects body size better than weight alone for many purposes.
Which BSA formula should I use?
The Mosteller formula is the most widely used because it is simple and accurate enough for clinical dosing. Du Bois is the older standard and gives very similar results. This tool shows both.
What is an average body surface area?
For an average adult it is roughly 1.7 m², with most adults falling between about 1.5 and 2.0 m². Children have proportionally higher BSA for their weight.
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