Body Surface Area (BSA) Calculator — Free Online
Calculate your Body Surface Area using the Mosteller formula. Enter your height and weight to get BSA in m2 with a clinical classification. 100% private, no sign-up.
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Your Body Surface Area
0.00 m2
BSA Classification
Small: Below 1.5 m2
Average: 1.5 - 2.0 m2
Large: Above 2.0 m2
Common Uses of BSA
Drug Dosing: Chemotherapy and other medications are often dosed based on BSA (mg/m2) rather than weight.
Cardiac Index: Cardiac output divided by BSA gives cardiac index, used to assess heart function.
Burn Assessment: The "Rule of Nines" uses BSA percentages to estimate burn severity.
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Frequently Asked Questions
Body Surface Area (BSA) is the total surface area of the body in square meters. It is used in medicine for drug dosing, cardiac index calculation, and burn assessment. The average adult BSA is approximately 1.7 m2.
The Mosteller formula is: BSA (m2) = sqrt((height in cm x weight in kg) / 3600). It is widely used for its simplicity and accuracy across different body types.
BSA is used for chemotherapy dosing, cardiac index calculation, and assessing burn severity. BSA-based dosing is considered more accurate than weight-based dosing for certain drugs because it accounts for both height and weight.
Average adult BSA is about 1.7 m2. Men typically range 1.6-2.0 m2, women 1.4-1.8 m2. Newborns have about 0.25 m2. BSA varies with height, weight, age, and body composition.
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Last updated: June 2026