Body Surface Area (BSA) is used in clinical settings to calculate drug dosages (especially chemotherapy), determine cardiac index, and assess burn severity.
Common Formulas
- DuBois: BSA = 0.007184 × W^0.425 × H^0.725
- Mosteller: BSA = √(W × H / 3600)
- Haycock: BSA = 0.024265 × W^0.5378 × H^0.3964
Where W = weight in kg, H = height in cm.
Average BSA
Adult male: ~1.9 m². Adult female: ~1.6 m². Average BSA is used as the reference for "standard" drug doses.
Why BSA Is Preferred Over Weight-Based Dosing
For drugs with a narrow therapeutic window — especially chemotherapy — BSA correlates more closely with blood volume, metabolic rate, and organ function than body weight alone, reducing the risk of under- or over-dosing across very different body types. This is why oncology dosing is almost universally expressed in mg per m² rather than mg per kg.
Formula Differences in Practice
The DuBois formula (1916) remains the most widely cited despite being derived from just 9 subjects; the Mosteller formula is simpler to calculate and produces very similar results for most adults, which is why both remain in common clinical use today.