How BSA is calculated (Mosteller formula)
The Mosteller formula estimates total body surface area from height and weight. It's the most widely used BSA formula in clinical practice because it's simple to compute while staying close to more complex reference formulas.
- height — height in centimeters
- weight — body weight in kilograms
- 3600 — the constant divisor the formula uses
More detail
Why BSA matters clinically
Many chemotherapy and pediatric drug doses are prescribed per square meter of body surface area rather than by weight alone, since BSA tracks metabolic rate and organ function more closely than weight does. BSA is also used to estimate the extent of burns as a percentage of total body surface.
Mosteller vs. other formulas
Older formulas like Du Bois (1916) use a more complex power equation; Mosteller (1987) simplified this to a single square root while staying within a few percent of Du Bois for most adults, which is why it's now the most commonly cited version in hospitals.
Quick check. A height of 180 cm and weight of 80 kg gives exactly 2.00 m² under the Mosteller formula (√(180×80/3600) = √4 = 2) — a fast way to sanity-check the calculator.
Frequently asked questions
How is body surface area calculated?
The Mosteller formula is BSA(m²) = √(height(cm) × weight(kg) / 3600). For example, a height of 180 cm and weight of 80 kg gives √(180×80/3600) = √4 = exactly 2.00 m².
What is BSA used for in medicine?
BSA is used to calculate drug doses (especially chemotherapy and pediatric medications) per square meter of body surface rather than by weight alone, and to estimate the percentage of body surface affected by burns.
What's a typical adult BSA?
Most adults fall roughly between 1.5 and 2.0 m², with the exact value depending on height and weight — enter your own numbers above to see your BSA.
Is the Mosteller formula accurate enough for clinical use?
Mosteller is a widely used clinical standard, but it's still a formula-based estimate. Dosing decisions should always be confirmed by a qualified healthcare professional using validated clinical methods, not this calculator alone.