Calculate body surface area (BSA) using the Mosteller or Du Bois formula.
Calculated instantly in your browser.
How do you calculate body surface area (BSA)?
Mosteller: BSA = √(height(cm) × weight(kg) ÷ 3600). Du Bois: BSA = 0.007184 × height(cm)^0.725 × weight(kg)^0.425. BSA reflects metabolic mass better than weight alone, so many drug doses are scaled to it. A person 180 cm tall weighing 80 kg has a BSA of about 2.0 m² by either formula. Mosteller is simplest; Du Bois is the historical standard.
Understanding your result
Body surface area better reflects metabolic mass than weight alone, which is why many drug doses and physiological measures are scaled to it. The Mosteller formula is the simplest; Du Bois is the historical standard.
Formula and method
Mosteller: BSA = √(height(cm) × weight(kg) ⁄ 3600). Du Bois: BSA = 0.007184 × height(cm)^0.725 × weight(kg)^0.425.
Assumptions and limitations
This tool estimates body surface area from height and weight using established formulas; it is educational and does not itself calculate or check drug doses. The Mosteller and Du Bois results are approximations that can differ slightly and may be less reliable at the extremes of body size. Clinical dosing must be left to qualified professionals.
Worked example
A person 180 cm tall weighing 80 kg has a BSA of about 2.0 m² by either formula.
How to use this tool
- Enter your weight and height with units.
- Choose the Mosteller or Du Bois formula.
- Read your body surface area in m².
Common mistakes to avoid
- Entering height in the wrong unit.
- Using BSA for actual dosing without professional guidance.
About the Body Surface Area Calculator
The Body Surface Area Calculator estimates your BSA in square metres from your height and weight, using the Mosteller or Du Bois formula. BSA is widely used in medicine to scale doses and other measures.
Who should use this tool
Healthcare students and professionals, and anyone curious about this clinical measure.
Benefits
- Two trusted BSA formulas.
- Metric or imperial input.
- Shows both formula results for comparison.
- Instant and private.
Practical use cases
- Estimating BSA for a dosing example.
- Comparing the Mosteller and Du Bois methods.
- Learning a clinical calculation.
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Frequently asked questions
Which BSA formula should I use?
Mosteller is popular for its simplicity and accuracy; Du Bois is the long-standing standard. They usually agree to within a couple of percent.
Why is BSA used for drug dosing?
Because it correlates with metabolic rate and blood volume better than body weight, giving more consistent dosing across body sizes.
Why do the two formulas give slightly different answers?
The Mosteller and Du Bois formulas were derived from different data and use different mathematical forms, so they can produce marginally different figures for the same height and weight. Both are widely accepted approximations, and the small gap between them is normal rather than an error.