Body Surface Area Calculator
How it works
The Mosteller formula is BSA = √(height_cm × weight_kg ÷ 3600), giving a result in square metres. Height and weight entered in inches or pounds are converted to centimetres and kilograms first, so the same body gives the same BSA whichever units were typed.
A typical adult BSA lands somewhere around 1.6–2.0 m², though it scales with both height and weight — there is no single "normal" value, only what a given height and weight combination works out to.
Frequently asked questions
What is body surface area actually used for?
It is mainly a reference figure used in clinical settings — for example some medication doses and lab measurements are conventionally scaled to BSA rather than to weight alone, because it tracks metabolic size a little better. That is a clinical dosing convention, not something to use for working out a dose yourself; medication amounts should always come from a prescriber or pharmacist.
Why the Mosteller formula specifically?
It is one of the simplest widely-cited formulas — height and weight, no fitted exponents — which is why it shows up so often. Other formulas exist (du Bois and Haycock are two common ones) and give slightly different numbers for the same person, typically within a few percent, so treat any single BSA figure as an estimate rather than an exact quantity.
Is this medical advice?
No. This is arithmetic on a height and a weight, useful as a general reference figure. It is not a personalised health assessment and it is not a basis for dosing anything yourself.