Body Surface Area (BSA) & Chemo Dosing Practice
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Many chemotherapy and some pediatric drugs are dosed per square meter of body surface area (BSA). The Mosteller formula is the standard, simplest method and the one tested most often. Keep BSA unrounded until the final multiplication to avoid dosing errors.
FormulaBSA (m²) = √(height[cm] × weight[kg] ÷ 3600) • dose = mg/m² × BSA
Worked example
A patient is 170 cm and 70 kg. BSA = √(170 × 70 ÷ 3,600) = √3.306 = 1.82 m². A 175 mg/m² order → 175 × 1.82 = 318.5 mg.
💡 Rounding trap: rounding BSA to one decimal too early can shift the dose by several mg — carry full precision to the end.