Body Surface Area (BSA) Calculator — Mosteller & Du Bois
Body Surface Area (BSA) is the measured or calculated surface of the human body, used for drug and chemotherapy dosing, cardiac index and fluid management. Enter height and weight to compute BSA using both the Mosteller and Du Bois formulas.
What is body surface area?
Body Surface Area (BSA) expresses the total surface of the body in square metres (m²). Because it correlates with metabolic rate, cardiac output and organ size better than body weight alone, it is the preferred basis for dosing many medications — particularly cytotoxic chemotherapy.
The formulas
BSA = √( (heightcm × weightkg) / 3600 )BSA = 0.007184 × heightcm0.725 × weightkg0.425Typical values
The average adult BSA is approximately 1.7 m²— around 1.9 m² for men and 1.6 m² for women. Always confirm dosing against local protocols and a clinician’s review.
Frequently asked questions
What is the Mosteller formula for BSA?+
BSA (m²) = √((height in cm × weight in kg) ÷ 3600). It is the most widely used formula because it is simple and accurate. For a 170 cm, 70 kg adult, BSA = √((170 × 70) ÷ 3600) ≈ 1.82 m².
Why is body surface area used for drug dosing?+
Many drugs — especially chemotherapy agents — correlate better with BSA than with body weight, because BSA tracks metabolic rate and organ size. Doses are often prescribed as an amount per m².
What is a normal BSA?+
The average adult BSA is about 1.7 m² (roughly 1.9 m² for men and 1.6 m² for women). Children have proportionally smaller values.
Mosteller vs Du Bois — which should I use?+
Both are validated. Mosteller is preferred for its simplicity and is standard in oncology. Du Bois (1916) is the classic reference. This tool shows both so you can compare.
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