Body surface area calculator
Enter your height and weight to estimate your body surface area in square meters. The three best-known formulas are shown side by side, so you can use the one your clinic or protocol names.
Runs in your browser: nothing you enter is sent anywhere.
How to use it
- Choose metric or US units.
- Enter your weight and height.
- Read the BSA in m² by each formula.
With weight W in kilograms and height H in centimeters:
- Mosteller (New England Journal of Medicine, 1987): BSA = √(H × W ÷ 3600)
- Du Bois and Du Bois (Archives of Internal Medicine, 1916): BSA = 0.007184 × W^0.425 × H^0.725
- Haycock et al. (Journal of Pediatrics, 1978): BSA = 0.024265 × W^0.5378 × H^0.3964
Pounds, feet and inches are converted exactly (1 lb = 0.45359237 kg, 1 in = 2.54 cm).
Worked example
A person who weighs 70 kg and is 175 cm tall:
- Mosteller: √(175 × 70 ÷ 3600) = √3.4028 = 1.84 m²
- Du Bois: 0.007184 × 70^0.425 × 175^0.725 = 1.85 m²
- Haycock: 0.024265 × 70^0.5378 × 175^0.3964 = 1.85 m²
Limits and tips
- The formulas are estimates fitted on samples of people. They can be less accurate for very small children and for very obese or very lean people.
- Tools like this give general information. Medical dosing and treatment decisions must come from your doctor or pharmacist.
Frequently asked questions
What is body surface area used for?
Doctors use BSA to scale some doses, notably chemotherapy, and to index measurements such as cardiac output and kidney function to body size. Your care team will say which formula to use.
Which formula is the most accurate?
They agree within a few percent for most adults. Mosteller (1987) is the easiest to compute by hand and is widely used. Du Bois (1916) is the classic reference, and Haycock (1978) was fitted on a sample that included infants and children.
What is an average BSA?
A value of about 1.7 m² is often quoted for adults, with women somewhat lower and men higher. The result for your size can differ.
Can I use it for dosing medicine?
No. Dose decisions belong to the prescriber, who may cap BSA, round it or use another formula. Use this calculator for information only.