Body Surface Area (BSA) Calculator: Mosteller & Du Bois

Height

Weight

BSA (Mosteller)

1.82m²

Du Bois: 1.81 m² · Average: 1.81 m²

The formulas

Mosteller (simpler, most commonly used):

BSA = √(Height × Weight)3600

Du Bois (classic):

BSA = 0.007184 × Height⁰⊹³⁵ × Weight⁰⊴²⁵

Both formulas give very similar results for adults in the normal BMI range. Mosteller is preferred clinically because it’s easier to compute mentally.

When BSA matters

Chemotherapy dosing — most cytotoxic regimens are dosed in mg/m²
Cardiac index — cardiac output normalised to body size (L/min/m²)
Burn assessment — used alongside the Rule of Nines
Renal function — GFR is sometimes indexed to 1.73 m²

Clinical tip: For chemotherapy, capping BSA at 2.0–2.2 m² is institution-dependent. Confirm with your oncology pharmacist.

Frequently asked questions

Which formula should I use — Mosteller or Du Bois?

For routine clinical use, Mosteller is simpler and produces virtually identical results to Du Bois in normal-weight adults. Du Bois may underestimate BSA in very obese patients; Mosteller is more robust across body sizes.

Is BSA used for paediatrics?

Yes — BSA is the standard for paediatric chemotherapy and some other drug classes. Mosteller is also commonly used in paediatrics for its simplicity.

What about very obese patients?

BSA can overestimate effective drug clearance in morbid obesity. Many oncology protocols use ideal or adjusted body weight rather than actual weight in obese patients.

Clinical safety notice. BSA-based dosing requires institutional verification. Always follow your facility’s protocols for cytotoxic and high-risk drugs.