Body Surface Area (BSA) Calculator — Mosteller & DuBois
Compute body surface area in m² using the Mosteller (1987) and DuBois (1916) formulas — the two BSA equations most commonly used for chemotherapy and pediatric drug dosing.
√(h · w / 3600)
0.007184 · h^0.725 · w^0.425
Refs: Mosteller RD, NEJM 1987;317:1098. DuBois D & DuBois EF, Arch Intern Med 1916;17:863. Clinical decision support tool — confirm dosing with reference texts; not a substitute for clinical judgment. Runs in your browser.
General calculation reads
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About this tool
Body surface area (BSA) is used in clinical medicine — particularly oncology and pediatrics — to scale drug doses to body size more accurately than weight alone, because BSA tracks better with metabolic rate and cardiac output. Several BSA formulas exist; the two used in practice are Mosteller (1987), preferred for its simplicity and adequate accuracy across adults and children, and DuBois & DuBois (1916), the older equation that still appears in chemotherapy protocols and reference texts. The Mosteller formula is BSA (m²) = √( height (cm) × weight (kg) / 3600 ). The DuBois formula is BSA (m²) = 0.007184 × height (cm)^0.725 × weight (kg)^0.425. This calculator computes both, side by side, so you can see the small difference — typically within a few percent — between them. Reference: Mosteller RD, N Engl J Med 1987;317:1098. DuBois D, DuBois EF, Arch Intern Med 1916;17:863. This is a clinical decision support tool — confirm dosing with reference texts; not a substitute for clinical judgment.
How to use it
- Enter height (cm) and weight (kg). Toggle to imperial if you prefer inches and pounds.
- Read BSA from both Mosteller and DuBois formulas.
- Pick whichever formula your local protocol specifies.
Frequently asked questions
- Which BSA formula should I use?
- Mosteller is the most widely used in modern practice because it is simple and accurate. DuBois is still cited in older chemotherapy nomograms. Always follow your institution's protocol — different cancer centres standardise on different formulas.
- How accurate is BSA?
- BSA formulas are population approximations and can disagree by a few percent. For chemotherapy, the resulting dose differences are usually small but can matter at extremes of weight; many protocols cap or adjust BSA in obese patients.
- Does BSA work for children?
- Yes — Mosteller is validated down to infancy. Pediatric oncology protocols routinely use BSA-based dosing for children above a certain age or weight, though weight-based dosing is preferred for infants.
- What is the average BSA for an adult?
- About 1.7 m² for an average adult man and 1.6 m² for an average adult woman. The "standard" dose-normalisation reference is 1.73 m².
- Why metres-squared, not square feet?
- BSA is reported in m² in essentially all clinical literature worldwide, including US oncology. Drug doses are written as "mg/m²", so m² is the unit you actually need.
- Is anything sent anywhere?
- No. Calculation runs in your browser.