Body Surface Area (BSA) Calculator
Calculate body surface area in m² using the Mosteller, DuBois & DuBois, and Boyd formulas — used in medical dosing and clinical settings.
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Body Surface Area in Clinical Medicine
Body Surface Area (BSA) is the measured or calculated surface of a human body in square meters. Unlike body weight, BSA correlates more accurately with many physiological parameters, making it the preferred basis for dosing certain medications — particularly in oncology (chemotherapy dosing), cardiac output assessment, and burn injury assessment.
Mosteller: BSA = √[(height(cm) × weight(kg)) / 3600]
DuBois: BSA = 0.007184 × height(cm)^0.725 × weight(kg)^0.425
Boyd: BSA = 0.0003207 × height(cm)^0.3 × weight(g)^(0.7285 − 0.0188 × log₁₀(g))
DuBois: BSA = 0.007184 × height(cm)^0.725 × weight(kg)^0.425
Boyd: BSA = 0.0003207 × height(cm)^0.3 × weight(g)^(0.7285 − 0.0188 × log₁₀(g))
Which Formula Should Be Used?
| Formula | Best Use Case | Notes |
|---|---|---|
| Mosteller | General clinical use | Simplest, most widely used in clinical practice |
| DuBois & DuBois | Adults of average build | Original 1916 formula; slightly less accurate at extremes |
| Boyd | Pediatrics | Validated across a wider range including neonates |
Normal BSA Values
The average adult has a BSA of approximately 1.7–1.9 m². Average male: ~1.9 m². Average female: ~1.6 m². Neonates: ~0.25 m².
Clinical Applications of BSA
- Chemotherapy dosing: Most cytotoxic agents are dosed in mg/m² to normalize across body sizes and reduce toxicity risk
- Cardiac output indexing: Cardiac index = cardiac output / BSA, normalizing for body size
- Burn assessment: The Rule of Nines (and Lund-Browder chart for children) estimates %BSA burned to guide fluid resuscitation
- Renal function: GFR is often expressed per 1.73 m² (the average adult BSA) for standardized comparison
BSABody Surface AreaClinical DosingMosteller Formula