Body Surface Area Calculator
Enter your height and weight to see your body surface area from four standard formulas.
This is an estimate for general information and is not medical advice. Do not use this page to work out a dose of any medicine. Your care team does that for you.
Worked examples
170 cm, 70 kg
Height 170 cm, weight 70 kg
Mosteller 1.82 m², Du Bois 1.81 m²
Haycock 1.83 and Gehan-George 1.83.
About Body Surface Area Calculator
Body surface area, or BSA, is the total area of your skin, measured in square metres. An average adult has about 1.7 to 1.9 square metres. It is used in physiology and research to compare body size, and to scale measurements such as the amount of blood the heart pumps each minute. This page works it out from your height and weight with four widely published formulas.
The Mosteller formula (1987) is the easiest: the square root of height in centimetres times weight in kilograms, divided by 3,600. Du Bois and Du Bois (1916), Haycock (1978) and Gehan and George (1970) use powers of height and weight and give answers within a few percent of each other for adults. This page is for general information. It is an estimate and not medical advice, and must not be used to work out medicine doses.
How to use Body Surface Area Calculator
- Choose metric or imperial units.
- Enter your height and weight.
- Read the Mosteller and Du Bois figures at the top.
- Compare the other formulas in the table, in square metres and square feet.
Common uses
- Comparing body size between people
- Scaling a measurement in a study or assignment
- Checking your own BSA out of interest
- Checking a worked example against a textbook
Frequently asked questions
What is the average body surface area?
About 1.9 square metres for an average man and 1.6 for an average woman, though the numbers vary with height and weight. The page shows your own estimate.
Which BSA formula is best?
Mosteller is simple and widely used. Du Bois is the oldest and often quoted. For most adults the answers are within about 2 to 3% of each other. Haycock and Gehan-George were designed with children in mind as well.
How is Mosteller worked out?
Multiply height in centimetres by weight in kilograms, divide by 3,600 and take the square root. For 170 cm and 70 kg that is the square root of 3.3056, or 1.82 square metres.
Can I use this for medicine doses?
No. Some medicines are dosed by body surface area, but those calculations are done by trained staff using their own checks. Do not use this page for doses. It is an estimate and not medical advice.
Does body surface area change with weight loss?
Yes, a little. A drop in weight reduces BSA slightly, though height has a bigger effect. Update the weight to see how much.