Which formula is most commonly used to calculate a child’s body surface area (BSA) for dosing?

• A. Du Bois formula
• B. Haycock formula
• C. Gehan and George formula
• D. Mosteller formula: BSA (m^2) = sqrt(height cm × weight kg / 3600)

Answer: (D)

The main idea here is to connect a child’s body size to how much drug they should receive by using body surface area as a dosing proxy. Mosteller’s approach does this with simple math: take the child’s height in centimeters, multiply by their weight in kilograms, divide by 3600, and then take the square root. This yields the body surface area in square meters.

Why this one stands out is the balance it strikes between accuracy and practicality. It only requires two measurements and one straightforward calculation, which is easy to do by hand or with a basic calculator. Across a wide range of pediatric ages and sizes, this method provides results that are close to those produced by more complicated formulas and aligns well with dosing guidelines used in clinical practice. That combination of reliable performance and ease of use has made it the go-to choice for routine chemotherapy dosing in children.

Other formulas exist, but they involve more complex math or exponents and often yield noticeably different values for smaller children, which can complicate standardization and quick calculations in busy clinical settings.