How to Calculate Body Surface Area
What is Body Surface Area?
Body Surface Area (BSA) is used in medicine to calculate drug doses, burn area, and cardiac output. The Mosteller formula is the most widely used due to its simplicity.
Formula
Mosteller: BSA (m²) = √(Height(cm) × Weight(kg) / 3,600); DuBois: BSA = 0.007184 × H^0.725 × W^0.425
- BSA
- Body Surface Area (m²)
- H
- Height (cm)
- W
- Weight (kg)
Step-by-Step Guide
- 1Mosteller: BSA (m²) = √(Height(cm) × Weight(kg) / 3,600)
- 2DuBois: BSA = 0.007184 × H^0.725 × W^0.425
- 3Boyd: accounts better for extremes of weight
- 4Normal adult BSA: approximately 1.7–1.9 m²
Worked Examples
Input
175cm, 70kg (Mosteller)
Result
BSA = √(175×70/3600) = √3.403 = 1.845 m²
Frequently Asked Questions
Why is BSA used instead of weight for drug dosing?
BSA correlates better with physiological processes (metabolic rate, organ function) than weight alone.
What's the normal adult BSA range?
Typically 1.7–1.9 m². Average adult ≈ 1.8 m². Children much smaller proportionally.
Which formula should I use?
Mosteller is simpler and preferred in most modern clinical settings. DuBois and Boyd for specific populations.