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Body Surface Area (BSA) Calculator
Estimate body surface area with four common formulas and see how BSA compares to other health metrics.
Measurements
Body surface area is based on height and weight.
What BSA tells you
Body surface area (BSA) estimates the total outer surface of the body. Clinicians use BSA to normalize drug dosing, compare kidney function, and scale physiologic measurements across people of different sizes. It is not a diagnostic measurement on its own, but it helps interpret other health data in context.
Formulas used in this calculator
- Du Bois: BSA = 0.007184 × height(cm)0.725 × weight(kg)0.425.
- Mosteller: BSA = √((height(cm) × weight(kg)) / 3600).
- Haycock: BSA = 0.024265 × height(cm)0.3964 × weight(kg)0.5378.
- Gehan & George: BSA = 0.0235 × height(cm)0.42246 × weight(kg)0.51456.
Why multiple formulas?
Each formula was derived from a different population and measurement set. Mosteller is widely used because it is simple and aligns closely with Du Bois, while Haycock is often cited in pediatric settings. Gehan & George offers another research-backed estimate. Comparing them side by side helps you see the range of results and choose the formula your clinician prefers.
How to use your result
- Pair BSA with BMI to understand both body size and surface area.
- Use BSA when reviewing lab values like estimated GFR that scale to body size.
- Track changes over time as weight or height measurements change.
BiteCheck helps you keep body measurements, nutrition targets, and health insights in one place so you can turn calculator results into daily action.
FAQ
What is body surface area (BSA)?
BSA estimates the total surface of the human body. It is used in clinical contexts like medication dosing and kidney function reporting.
Which BSA formula should I use?
Mosteller is common for clinical workflows because it is easy to calculate and aligns closely with more complex formulas.
Do height and weight units matter?
Use metric or imperial—this calculator converts inputs to centimeters and kilograms before applying the formulas.
Is BSA the same as BMI?
No. BMI relates weight to height squared, while BSA estimates total body surface. They answer different health questions.
Can children use the calculator?
Yes. The Haycock formula is often cited for pediatric use, but always verify clinical decisions with a professional.
Is BSA a medical diagnosis?
No. BSA is an estimate and should be interpreted alongside clinical judgment and other measurements.
Informational only, not medical advice. Consult a healthcare professional for personalized guidance.
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