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BSA Calculator — Mosteller Formula
The Mosteller formula is the bedside default for body surface area, and this calculator applies it directly: BSA (m²) = √(height in cm × weight in kg ÷ 3600). It is popular because it is simple enough to compute by hand yet agrees closely with the older, more complex equations. Take a person 180 cm tall weighing 75 kg: √(180 × 75 ÷ 3600) = √3.75 = 1.94 m². Enter height and weight in metric or imperial units to see the Mosteller result alongside Du Bois, Haycock, Gehan-George and Boyd, so you can confirm they agree at average size and spot where they diverge at obesity and pediatric extremes. BSA (m²) is used for chemotherapy and drug dosing, cardiac index and pediatric calculations. This is an estimate — clinical and chemotherapy dosing must be independently clinically verified. Free, private, and computed entirely in your browser.
Mosteller: BSA (m²) = √(cm × kg ÷ 3600)
- Worked example: √(180 × 75 ÷ 3600) = 1.94 m²
- Shown side by side with Du Bois, Haycock, Gehan-George and Boyd
Frequently asked questions
What is the Mosteller formula for BSA?
Mosteller BSA (m²) = √(height in cm × weight in kg ÷ 3600). For 180 cm and 75 kg that is √(180 × 75 ÷ 3600) = √3.75 = 1.94 m². It is the simplest widely-used formula and the bedside default; it agrees with Du Bois and the other equations to about 0.01 m² at an average build. It is an estimate — verify clinically for dosing.
Why is Mosteller the preferred BSA formula?
Mosteller is preferred at the bedside because it is easy to compute — just a square root — yet validated against the older Du Bois and Boyd equations, which it matches closely at average size. It is also commonly used in infants and children. When a dose depends on BSA in an obese or pediatric patient, use the formula your protocol specifies.