Body Surface Area (BSA) Calculator

Enter height in centimetres and weight in kilograms. The tool shows body surface area in square metres from two published formulas, each to two decimals:

• Du Bois (1916), the headline figure: BSA = 0.007184 × weight^0.425 × height^0.725
• Mosteller (1987), shown underneath: BSA = √(height × weight ÷ 3600)

With the defaults, 175 cm and 70 kg, Du Bois gives 1.85 m² and Mosteller gives 1.84 m². Both are estimates from height and weight, not measurements and not a diagnosis.

Mosteller is easy to check with any phone calculator, which is useful when you want to confirm a figure you've been given:

1. Multiply height by weight: 175 × 70 = 12,250.
2. Divide by 3,600: 3.4028.
3. Take the square root: 1.845.

The tool rounds that to 1.84. Du Bois uses fractional powers, so it really needs a calculator with an exponent key.

For average builds the formulas agree to within a hundredth or two. They drift further apart for heavier people:

The tool doesn't pick one for you. If you are matching a figure on a document, check which formula it names.

Use the result to understand a figure, not to set one. If a BSA appears on a prescription or treatment plan, your care team worked it out from their own measurements and method, and any question about a dose belongs with them.

Measured weight and height make a real difference here: a few centimetres of guessed height or an old weight changes the second decimal.