Body Surface Area Calculator
Calculate body surface area (BSA) from height and weight using the Mosteller and Du Bois formulas, widely used in medicine and dosing. Free, private, instant.
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Estimate body surface area from height and weight
Body surface area is used in medicine, especially for dosing certain drugs and assessing physiology, because it tracks metabolic size better than weight alone. This calculator estimates it from height and weight using the Mosteller and Du Bois formulas, the two most widely used.
Why surface area, and why two formulas
Some medication doses, notably in chemotherapy, are calculated per unit of body surface area rather than per kilogram, because surface area correlates better with how the body processes those drugs. The Mosteller formula is simple enough to compute by hand; the Du Bois formula is older and slightly different. Showing both lets you compare, and their small disagreement is a reminder that surface area is itself an estimate.
A clinical estimate, framed honestly
These are estimates from a standard formula for general information, not medical advice. Individual health depends on far more than any single number, so treat the result as a rough guide and consult a professional for anything that matters. The calculation runs entirely in your browser, so your figures are not uploaded.
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Frequently Asked Questions
What is body surface area used for?
Estimating metabolic size for physiology and, importantly, for calculating certain drug doses, notably in chemotherapy, that are prescribed per unit of surface area rather than per kilogram.
Why estimate it from height and weight?
Because measuring true surface area directly is impractical, so validated formulas estimate it from height and weight, which correlate with it well.
Why show two formulas?
The Mosteller formula is simple to compute; the Du Bois formula is older and slightly different. Comparing them shows the small uncertainty inherent in any surface-area estimate.
How accurate is it?
It is an estimate from validated formulas, adequate for its clinical purposes but not an exact physical measurement.
Is this medical advice?
No. It is a general estimate. Clinical dosing must be done by a qualified professional.
Privacy & Security
All processing happens locally in your browser — nothing is uploaded.
How to Use
Enter your height and weight to calculate BSA from two standard formulas.
Disclaimer: This tool is provided "as is" without warranty of any kind. Results are for educational and utility purposes.
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