Body Surface Area Calculator

How This Calculator Works

Body surface area (BSA) is an estimate of your total skin surface, calculated from height and weight rather than measured directly. It’s used clinically for things that scale better with body size than with weight alone, such as certain medication dosing calculations. Enter your height and weight, and this calculator shows the estimate from three published formulas side by side — plus their average.

The Formulas

Every formula below uses the same two inputs — weight (kg) and height (cm) — so the same two colors track the same two quantities across all three:

DuBois & DuBois (1916) — the oldest and most widely cited BSA formula, still a common clinical default over a century later:

$$\text{BSA} = 0.007184 \times \vA{\text{Weight}}^{0.425} \times \vB{\text{Height}}^{0.725}$$

Mosteller (1987) — a simpler square-root formula that closely approximates DuBois while being easy to compute by hand:

$$\text{BSA} = \sqrt{\frac{\vB{\text{Height}} \times \vA{\text{Weight}}}{3600}}$$

Haycock (1978) — developed using data that included infants and children, so it’s often preferred for pediatric use:

$$\text{BSA} = 0.024265 \times \vA{\text{Weight}}^{0.5378} \times \vB{\text{Height}}^{0.3964}$$

Worked Example

A person who is 180 cm (5’11”) tall and weighs 80 kg (176 lb):

1. DuBois: $0.007184 \times \vA{80}^{0.425} \times \vB{180}^{0.725} \approx 1.996 \text{ m}^2$
2. Mosteller: $\sqrt{(\vB{180} \times \vA{80}) \div 3600} = 2.000 \text{ m}^2$
3. Haycock: $0.024265 \times \vA{80}^{0.5378} \times \vB{180}^{0.3964} \approx 2.007 \text{ m}^2$
4. Average: $(1.996 + 2.000 + 2.007) \div 3 \approx 2.001 \text{ m}^2$