Body Surface Area Calculator
Calculate BSA using the Mosteller, DuBois & DuBois, and Haycock formulas side by side. Used for drug dosing reference, burn assessment, and cardiac index calculations.
1.82 m²
BSA (M²)
Mosteller
Formula
Average Adult
Category
Enter Your Measurements
ℹ️ Mosteller is the most widely used clinical formula — simple, fast, and the default in most EHR systems.
⚠️ For educational reference only. Clinical drug dosing requires verification by a licensed healthcare professional.
Body Surface Area
1.82 m²
Mosteller formula · male · 70 kg, 170cm
≈ 19.57 ft²
1.818 m²
BSA (Primary)
1.818 m²
Mosteller
1.810 m²
DuBois
1.826 m²
Haycock
All 3 Formula Results — Side by Side
All three formulas typically land within about 0.05 m² of each other — small differences are expected and not a sign of error.
Simplest formula to compute by hand; the default in most hospitals and EHR systems.
BSA = √((Height(cm) × Weight(kg)) / 3600)The original formula, derived from just 9 subjects — still widely referenced a century later.
BSA = 0.007184 × Height(cm)^0.725 × Weight(kg)^0.425Validated across a wider weight range, including infants — often preferred for pediatric dosing.
BSA = 0.024265 × Height(cm)^0.3964 × Weight(kg)^0.5378Typical Adult BSA Reference Range
For context only — individual BSA varies widely with height and weight.
1.7–2.1 m²
Average Adult Male
1.5–1.9 m²
Average Adult Female
1.6–2.0 m²
Overall Adult Range
What Is Body Surface Area (BSA)?
Body surface area is an estimate of the total surface area of the human body, expressed in square meters (m²). Because it accounts for both height and weight together, BSA tracks metabolic rate, blood volume, and organ function more closely than weight alone — which is why it plays a role in three main clinical settings: dosing medications with a narrow safety margin (chemotherapy above all), estimating the percentage of body surface affected by a burn, and normalizing cardiac output into a cardiac index that can be compared fairly across patients of different sizes. For a related kidney-function metric that is itself BSA-normalized, see our GFR calculator.
🧮 The 3 BSA Formulas
Mosteller (1987): BSA = √((Height(cm) × Weight(kg)) / 3600) — simplest, most widely usedDuBois & DuBois (1916): BSA = 0.007184 × Height(cm)^0.725 × Weight(kg)^0.425 — the original formulaHaycock (1978): BSA = 0.024265 × Height(cm)^0.3964 × Weight(kg)^0.5378 — preferred for pediatric use⚠️ Medical Disclaimer: This calculator is provided for educational and reference purposes only. BSA-based drug dosing — including chemotherapy — must be calculated, verified, and prescribed by a licensed healthcare provider. Never use this tool to calculate or adjust an actual medication dose.
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Chemotherapy Dosing
Most chemotherapy agents are dosed in mg per m² of BSA rather than by weight, since it more closely reflects how the body distributes and clears the drug.
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Burn Assessment
Beyond the quick "Rule of Nines," BSA gives clinicians a more precise denominator for estimating what percentage of skin is affected and for guiding fluid resuscitation.
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Cardiac Index
Dividing cardiac output by BSA produces a cardiac index that can be compared fairly across patients of very different sizes, from a small adult to a large one.
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Why Formulas Differ Slightly
Each formula was derived from a different research sample and era. They agree closely for typical adults but can diverge a little more at height or weight extremes.
— FAQ