Body surface area calculator
Body surface area (BSA) from height and weight, with the Mosteller and Du Bois formulas.
About this calculator
This body surface area calculator estimates the total surface area of the body in square metres, from height and weight.
BSA is used in medicine to set doses of some drugs, such as chemotherapy, and to compare heart and kidney measurements between people of different sizes.
How it works
The Mosteller formula is BSA = √(height in cm × weight in kg ÷ 3,600). The other formulas use different powers of height and weight and give similar results for most adults.
Last reviewed:
Worked example
- Units: Feet and pounds
- Height: 5 ft 7 in
- Weight: 155 lb
Body surface area: 1.82 m² (Mosteller formula)
Common questions
What is a normal body surface area?
For adults it's usually between about 1.6 and 2.0 m². An often-quoted average is 1.7 m², a little higher for men than for women.
Which BSA formula is best?
Mosteller is the most widely used because it's simple and accurate for most people. Du Bois is the classic, and Haycock is often used for children.
Why is BSA used instead of weight?
Body processes such as metabolism and blood flow scale more closely with surface area than with weight, especially across very different body sizes.
Sources and further reading
The story behind it
Where the idea came from: Delafield and Eugene Du Bois published their body surface area formula in 1916. Mosteller's simpler version followed in 1987.
The Du Bois cousins measured the skin of a handful of people by covering them in paper moulds. Their formula served for 70 years, until Mosteller showed that a square root of height times weight did the job just as well.
Why you can trust this calculator
- It runs in your browser. Nothing you type into it is sent anywhere.
- The method is explained on this page, so you can check it yourself.
- Free to use, with no sign-up.
- Results are estimates, not medical advice.
- Spotted a mistake? Tell us and we'll look into it.
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