Body Surface Area Calculator
Body surface area (BSA) is the total area of the outside of your body, estimated from your height and weight. Clinicians use it to scale medication doses (especially chemotherapy), calculate cardiac index, and assess kidney function, because BSA tracks metabolic needs better than weight alone. This calculator shows the Mosteller estimate — the simple square-root formula most widely used today — alongside the older Du Bois formula for comparison. The two agree closely. BSA here is a reference figure for general understanding; any clinical use, such as drug dosing, must be done by a qualified professional with verified measurements.
Calculate
Default result: 2.00
Body Surface Area Calculator · Result
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Mosteller (most common)
70.9 in × 176 lb
- Du Bois (1916)
- 2.00
This calculator provides an estimate for general information only and is not a medical diagnosis or professional advice. Body-composition and health-risk figures are approximations from population formulas and can differ meaningfully from clinical measurement. Do not use this result to diagnose, treat, or rule out any health condition — consult a qualified healthcare provider before acting on it.
Reviewed by the calculators.dev team · Last updated 2026-06-23
Formula reviewed against Mosteller RD. Simplified calculation of body-surface area. N Engl J Med 1987;317(17):1098 (Mosteller formula)
How to calculate
Enter your height and weight in whichever units you prefer; the calculator converts them. It then applies the Mosteller formula, the square root of height in centimetres times weight in kilograms divided by 3600, and also shows the Du Bois result. For 180 cm and 80 kg, the square root of (180 × 80 ÷ 3600) is the square root of 4, which is exactly 2.00 m². The Du Bois figure lands at essentially the same value, confirming the estimate.
Mosteller: BSA (m²) = √((height_cm × weight_kg) ÷ 3600). Du Bois: BSA (m²) = 0.007184 × weight_kg^0.425 × height_cm^0.725. Variables: height in centimetres and weight in kilograms (the calculator converts your units). The result is square metres. Mosteller is preferred for its simplicity and is accurate across the normal range; Du Bois, the original 1916 formula, can slightly underestimate at the extremes of body size.
Example calculation
For a person 1.80 m (180 cm) tall weighing 80 kg, the Mosteller formula gives √(180 × 80 ÷ 3600) = √4 = 2.00 m². The older Du Bois formula returns almost the same value (≈2.00 m²), which is why Mosteller — being simpler — is the one most clinicians use.
- mosteller
- 2.00 m²
- dubois
- 2.00 m²
Assumptions
- BSA is an estimate from height and weight, not a direct measurement of skin area, and assumes typical body proportions.
- Mosteller and Du Bois agree closely for normal builds; both can drift at the extremes of body size, with Du Bois tending to underestimate for very large bodies.
- Clinical applications such as drug dosing require professional oversight and verified measurements — the figure here is for general understanding.
Common mistakes
- Mixing up height units. The formula uses centimetres internally; entering metres in a centimetre field would collapse the result. The unit-aware fields here prevent that.
- Using a self-calculated BSA for actual medication dosing. Dosing must be done by a clinician with verified inputs.
- Expecting BSA to indicate body fat or fitness. It does not — it scales with overall body size, not composition.
Frequently asked questions
What is body surface area used for?
Clinicians use BSA to scale drug doses (notably chemotherapy), compute cardiac index, and normalise kidney-function measures. It reflects metabolic size better than weight alone, which is why it appears in many medical formulas.
Which BSA formula is most accurate?
Mosteller is the most widely used today because it is simple and accurate across the normal range. Du Bois, the original formula, agrees closely but can slightly underestimate at the extremes. This calculator shows both so you can compare.
Can I use this calculator for medication dosing?
No. This is a general reference figure. Clinical dosing based on BSA must be done by a qualified healthcare professional using verified measurements and the appropriate protocol.
Does body surface area tell me about my body fat?
No. BSA scales with overall body size, not composition, so it says nothing about body fat or fitness. For body composition, look at a body-fat or lean-body-mass estimate instead.