Body Surface Area Calculator
BSA in m² from height and weight by Mosteller, Du Bois, Haycock and more.
About this tool
Enter height and weight in centimetres and kilograms or in inches and pounds. The calculator shows body surface area by the Mosteller formula in square metres and square feet, with a table comparing four other published formulas, so you can see how closely they agree for your measurements.
How body surface area is calculated
Body surface area (BSA) is the estimated total area of the skin. It is used to scale chemotherapy and some other drug doses, to index measurements such as cardiac output and kidney function, and to plan fluids for burns. Measuring skin directly is impractical, so formulas estimate it from height and weight. Mosteller (1987) is the simplest: the square root of height in cm times weight in kg divided by 3,600. A person 170 cm tall weighing 70 kg has a BSA of about 1.82 m². Du Bois and Du Bois (1916) is the oldest and still common; Haycock, Gehan & George and Boyd were derived partly from children and are often preferred in paediatrics. For typical adults, the formulas agree within a few percent. They diverge more at the extremes of size, and clinicians may cap BSA in obesity. Average adult BSA is about 1.9 m² for men and 1.6 m² for women. Honest limits: this is general information, not medical advice, and dosing decisions belong to clinicians and their protocols. The BMI calculator, the ideal weight calculator and the body fat calculator use the same measurements; Is BMI accurate? explains the limits of height-and-weight formulas.
Frequently asked questions
What is a normal body surface area?
Average adult BSA is about 1.9 m² for men and 1.6 m² for women. Children's values are much smaller and change quickly with growth.
Which BSA formula is best?
Mosteller is the most widely used because it's simple and accurate for adults. Haycock or Gehan & George are often chosen for children.
Why is BSA used for drug doses?
Body size affects how drugs are distributed and cleared. BSA tracks metabolic rate better than weight alone, so some drugs, such as chemotherapy, are dosed per m².
Is my data saved?
No. The calculation runs in your browser and nothing is stored or sent.