How to calculate body surface area
Enter height and weight, then choose the formula your protocol uses.
Measure height and weight
Use the same units as the labels, without shoes or heavy clothing.
Pick a formula
Select the formula used by your institution or prescriber.
Compare the three
The row values show how much the formulas differ for this body size.
What does this tool do?
Body surface area scales drug doses, fluid needs and some physiological measures. Mosteller, Du Bois and Haycock are widely used formulas that differ slightly, so this tool reports all three and the selected result.
The Formula
Mosteller: √(H × W ÷ 3600); Du Bois: 0.007184 × W^0.425 × H^0.725; Haycock: 0.024265 × W^0.5378 × H^0.3964Frequently Asked Questions
Which BSA formula should I use?
Mosteller is simple and widely used; Du Bois and Haycock are common alternatives. Institutional protocols usually specify one formula for dose calculations.
Does BSA use actual body weight?
It normally uses measured height and weight. Severe obesity, oedema or amputation can make the estimate less representative, so clinical review is needed for dosing.