Body Surface Area Calculator
Calculate body surface area from height and weight using standard medical formulas, free and instant right in your browser.
Enter Values
Before you rely on this: First-pass guide only. Verify safety-critical or regulated work against the relevant standards, your project requirements and a qualified professional.
How to use this calculator
- Enter your height in centimetres and weight in kilograms.
- Press Calculate for the body surface area.
How it works
The Mosteller formula estimates body surface area: BSA = √(height in cm × weight in kg ÷ 3600), in square metres. It's used in some medical dosing.
Worked example
180 cm, 80 kg. √(180 × 80 ÷ 3600) = √4 = 2 m².
Common mistakes
- Mixing unit systems — enter height and weight in the units the tool shows so the conversion stays correct.
- Using BSA for drug dosing without a clinician — it is a screening estimate, not a prescription.
Frequently asked questions
Which BSA formula does this use?
It uses the Mosteller formula, √(height_cm × weight_kg ÷ 3600), the most common bedside method; Du Bois gives very similar results for most adults.
What is an average body surface area?
Around 1.7 m² for an average adult — roughly 1.6 m² for women and 1.9 m² for men — but it varies with height and weight.
What is body surface area used for?
Mainly medical dosing (some drugs and IV fluids are scaled by BSA). This is an estimate from the Mosteller formula — clinical decisions should use professional measurement.
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Cite this tool
Zerdly. (2026). Body Surface Area Calculator. Retrieved from https://www.zerdly.com/tools/body-surface-area-calculator/
Tip: Enter any known values to calculate the remaining results.
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