BSA Calculator — Body Surface Area (Mosteller, Du Bois, Haycock)
Enter your height and weight to calculate body surface area in square metres and square feet, with a side-by-side comparison of the three main BSA formulas — Mosteller, Du Bois, and Haycock.
cm
kg
Formula
Typical adult range: 1.5 – 2.1 m²
- 1
Height × Weight ÷ 3600
175 × 70 ÷ 3600 = 3.4028 - 2
Body surface area
√(3.4028) = 1.845 m²Mosteller: BSA = √(height_cm × weight_kg ÷ 3600)
How does this calculator work?
BSA (m²) = √(height_cm × weight_kg / 3600) by Mosteller — the most common formula. Du Bois (0.007184 × h^0.725 × w^0.425) and Haycock (0.024265 × h^0.3964 × w^0.5378) are alternatives used in specific clinical protocols. All three typically agree within 1–3% for average adults. A typical adult BSA is about 1.7 m².
Formula
How this is calculated
Body surface area (BSA) estimates the total external skin area of the body in square metres. It is used clinically to scale drug doses — particularly chemotherapy — more accurately than body weight alone, because many physiologic processes correlate better with surface area than mass.
Three formulas are available. The Mosteller formula (1987) is the simplest: BSA = √(height_cm × weight_kg / 3600). The constant 3600 (= 60²) is a dimensional scaling factor. Mosteller is widely preferred in clinical practice for its ease of mental calculation. The Du Bois formula (1916) was the first scientifically validated BSA equation: BSA = 0.007184 × h^0.725 × w^0.425. It is still used in some cardiac output and anaesthesia protocols. The Haycock formula (1978) was developed specifically for children and neonates: BSA = 0.024265 × h^0.3964 × w^0.5378; it performs slightly better across the paediatric weight range.
All three formulas are empirical regression equations calibrated on measured human data, not geometrically derived values, so they are statistical estimates rather than exact measurements. Results typically agree within 1–3% across formulas for typical adult bodies. At the extremes — very obese, very thin, or very young — divergence grows. For clinical dosing, always follow the specific formula mandated by your protocol.
Frequently asked questions
Mosteller is the most widely used in adult practice because it is simple and accurate. Use Haycock for children and neonates. Du Bois is often specified in older cardiac or anaesthesia protocols. When in doubt, follow the formula stated in the clinical guideline you are following.
Average adult BSA is approximately 1.7 m² (1.6 m² for women, 1.9 m² for men in reference populations). Most adults fall between 1.5 and 2.1 m².
Yes — many chemotherapy agents (e.g. carboplatin, 5-FU) are dosed in mg/m² to normalise for patient size. BSA-based dosing can reduce inter-patient variability compared to flat weight-based dosing, though it is not perfect for all drugs.
Also known as
TG we-Calculate Editorial Team. (2026). BSA Calculator — Body Surface Area (Mosteller, Du Bois, Haycock) [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/bsa-calculator
TG we-Calculate Editorial Team. "BSA Calculator — Body Surface Area (Mosteller, Du Bois, Haycock)." TG we-Calculate. 2026. https://we-calculate.com/calculator/bsa-calculator.
TG we-Calculate Editorial Team, "BSA Calculator — Body Surface Area (Mosteller, Du Bois, Haycock)," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/bsa-calculator
@misc{wecalculate_bsa_calculator, title = {BSA Calculator — Body Surface Area (Mosteller, Du Bois, Haycock)}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/bsa-calculator}}, year = {2026}, note = {TG we-Calculate} }
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