Body Surface Area
Definition
Body Surface Area (BSA) is the measured or calculated surface area of the human body, expressed in square meters (m²). BSA is critically important in medicine for calculating chemotherapy drug dosages, determining cardiac index, assessing burn severity, and adjusting medication doses for body size. The most common formula is the Du Bois formula: BSA (m²) = 0.007184 × Height(cm)^0.725 × Weight(kg)^0.425. Average adult BSA is approximately 1.7 m² for women and 1.9 m² for men. The Mosteller formula is a simpler alternative: BSA = √(Height(cm) × Weight(kg) ÷ 3600).
Why is Body Surface Area Important?
Understanding Body Surface Area empowers you to take control of your personal health and wellness. Whether you are tracking body composition, planning nutrition, or evaluating fitness metrics, this concept provides the foundation for making informed health decisions backed by science.
Our health calculators make these metrics accessible and easy to compute, giving you instant, evidence-based results so you can focus on achieving your wellness goals rather than crunching numbers.
What is Body Surface Area?
Body Surface Area (BSA) is the total surface area of the human body, measured in square meters (m²). BSA is critically important in medicine for calculating drug dosages (especially chemotherapy), determining cardiac output index, assessing burn severity, and adjusting treatment protocols for body size.
BSA Formulas
| Formula | Equation | Use |
|---|---|---|
| Du Bois (1916) | BSA = 0.007184 × H^0.725 × W^0.425 | Most widely used in clinical practice |
| Mosteller (1987) | BSA = √(H × W ÷ 3600) | Simplest — easy mental math |
| Haycock (1978) | BSA = 0.024265 × H^0.3964 × W^0.5378 | Most accurate for children |
| Gehan/George (1970) | BSA = 0.0235 × H^0.42246 × W^0.51456 | NCI cancer trials standard |
H = height in cm, W = weight in kg for all formulas
Average BSA Values
| Population | Average BSA |
|---|---|
| Adult male (average) | 1.9 m² |
| Adult female (average) | 1.6 m² |
| Newborn | 0.25 m² |
| Child (10 years) | 1.14 m² |
| Adolescent (15 years) | 1.50 m² |
Clinical Applications
- Chemotherapy dosing — Most cancer drugs are dosed per m² of BSA (e.g., cisplatin 75 mg/m²) because drug metabolism and clearance correlate with body surface area more than weight alone
- Cardiac Index — Cardiac output (L/min) ÷ BSA = Cardiac Index (normal: 2.5–4.0 L/min/m²), used to assess heart function independent of body size
- Burn assessment — The "Rule of Nines" estimates burn percentage of BSA: head = 9%, each arm = 9%, each leg = 18%, trunk front = 18%, trunk back = 18%, groin = 1%
- Renal function — GFR (glomerular filtration rate) is normalized to 1.73 m² BSA