Body Surface Area Calculator
Calculate body surface area (BSA) in square meters from height and weight using the Mosteller formula.
How it works
BSA (m²) = √(height(cm) × weight(kg) ÷ 3600)
Body surface area estimates the total area of your skin, which tracks metabolic needs better than weight alone. The Mosteller formula is the clinical favorite because it’s simple and accurate: the square root of height in centimeters times weight in kilograms, divided by 3,600. US units are converted first (1 lb = 0.4536 kg, 1 in = 2.54 cm).
Worked example
At 70 kg and 175 cm: BSA = √(175 × 70 ÷ 3600) = √3.40 ≈ 1.84 m².
Frequently asked questions
Why dose drugs by surface area?
BSA correlates with blood volume, kidney filtration and metabolic rate better than body weight, so for narrow-margin drugs like chemotherapy it gives a more even, safer dose across body sizes.
Mosteller or Du Bois?
Both are standard and usually agree within a couple of percent. Mosteller is easier to compute by hand, which is why it’s the common default; this page shows both.
What’s a typical BSA?
Roughly 1.7 m² for an average adult — near 1.9 m² for many men and 1.6 m² for many women — but it depends entirely on height and weight.
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General educational estimate, not medical advice. Talk to a doctor for anything about your health.