Body Surface Area Calculator
Calculate body surface area (BSA) with the Mosteller, Du Bois, Haycock and Boyd formulas.
About the Body Surface Area Calculator
Enter height and weight to see body surface area by four standard formulas side by side. The headline uses Mosteller, the most widely used.
Body surface area is used to dose chemotherapy and some other drugs, and to index measures like cardiac output. Mosteller's formula is the simplest; Haycock is often preferred for children.
The formula
Mosteller: BSA = √(height(cm) × weight(kg) ÷ 3600)
- Du Bois
- 0.007184 × W^0.425 × H^0.725
- Haycock
- 0.024265 × W^0.5378 × H^0.3964
Worked example
175 cm and 70 kg
- Mosteller: √(175 × 70 ÷ 3,600) = 1.845 m²
- Du Bois 1.848, Haycock 1.847, Boyd 1.851 m²
- All four agree within 0.4%
Things to keep in mind
- For clinical dosing, use your institution's approved formula and check with a pharmacist.
Questions people ask
Which formula should I use?
Mosteller unless your protocol names another; differences are usually under 5%.
What's a typical BSA?
About 1.9 m² for adult men and 1.6 m² for adult women.
Why not just use weight?
Many body processes scale with surface area rather than weight, so BSA can give more consistent dosing across body sizes.