Body Surface Area Calculator
Calculate body surface area (BSA) in m² using the Mosteller and Du Bois formulas from height and weight. Useful for chemo dosing and clinical estimates.
cm
kg
Results
Body Surface Area (Mosteller)
1.82 m²
Du Bois Formula
1.81 m²
Normal Adult Reference
~1.7–1.9 m²
Weight per m² (dosing ratio)
38.5 kg/m²
How is Body Surface Area Calculated?
Body Surface Area (BSA) estimates the total surface area of a human body from height and weight. The most common clinical method is the Mosteller formula: BSA (m²) = √((height_cm × weight_kg) / 3600). The older Du Bois formula — 0.007184 × Weight^0.425 × Height^0.725 — is also widely referenced and gives very similar results for adults.
Du Bois: BSA = 0.007184 × W^0.425 × H^0.725
Example
A person who is 170 cm tall and weighs 70 kg: Mosteller gives √((170 × 70) / 3600) ≈ 1.82 m². The Du Bois formula gives 0.007184 × 70^0.425 × 170^0.725 ≈ 1.81 m². Both fall in the typical adult reference range of roughly 1.7–1.9 m².
Common Use Cases
- Dosing chemotherapy and other medications that are scaled to body surface area rather than weight.
- Cardiac index calculations in critical care (cardiac output divided by BSA).
- Estimating burn area and fluid requirements (Parkland formula).
- Setting physiological reference values in clinical research.
FAQs
What is a normal BSA for an adult?
Most healthy adults have a BSA between roughly 1.7 and 1.9 m². Values outside this range simply reflect a person's size — taller and heavier individuals have a larger surface area. It is a derived estimate, not a fitness or health score on its own.
Why is BSA used for chemotherapy dosing?
Many chemotherapy drugs have a narrow therapeutic window, meaning the difference between an effective dose and a toxic one is small. Since many physiological processes scale more closely with surface area than with weight alone, dosing per m² improves accuracy compared with simple per-kg dosing.
Which formula should I use?
The Mosteller formula is the most commonly used today because it is simple, accurate for typical adult sizes, and easy to compute. The Du Bois formula predates it and is still referenced in many textbooks. For most adults the two agree within a few percent.