Body Surface Area Calculator
Calculate total body surface area (BSA) in square meters using Mosteller and DuBois clinical formulas.
BSA Output
Medical disclaimer. This calculator is for general information and education only. It is not medical advice, not a diagnosis, and not a substitute for professional care. Body surface area is used clinically for chemotherapy dosing and cardiac indices. Never use this figure to calculate or adjust a medication dose yourself.Speak to a doctor or another qualified clinician about any health decision.Last reviewed .
Frequently asked questions
What is Body Surface Area (BSA)?
Body Surface Area is the calculated surface area of a human body, frequently used in clinical medicine to dose medication.
Which body surface area formula should I use?
Du Bois is the historical standard and still the most cited; Mosteller is the most widely used in practice because its square-root form is easy to compute and it agrees closely with Du Bois across normal ranges. Haycock and Boyd are often preferred in paediatrics. For most adults the formulas agree within a few percent, so the choice rarely changes a decision.
Why is BSA used for drug dosing?
Body surface area correlates better with cardiac output, glomerular filtration and metabolic rate than body weight alone, so it scales doses more sensibly across very different body sizes. It is standard in chemotherapy dosing. The practice is not without criticism - BSA does not capture body composition - but it remains the convention for cytotoxic agents.
What is a normal BSA?
Roughly 1.9 m2 for an average adult man and 1.6 m2 for an average adult woman, with 1.73 m2 used as the reference value that kidney function is normalised to. Children range from about 0.25 m2 at birth to adult values in the late teens.