Body Surface Area Calculator · Practical guide
Du Bois vs Mosteller Formula
The original 1916 equation against the modern square-root shortcut — and how close the two really land.
At a glance
The Two Equations
Du Bois and Du Bois published the original BSA equation in 1916 from direct measurements of just nine subjects: BSA = 0.007184 × weight^0.425 × height^0.725 (weight in kg, height in cm). Mosteller's 1987 simplification replaces the exponents with a square root: BSA = √(weight × height ÷ 3600). This calculator returns both, plus Haycock and Boyd, on every run.
Interactive tool
Body Surface Area Calculator
Enter your own values, then compare the result with the examples below.
Body Surface Area Results
Same Patient, Both Formulas
| Patient | Du Bois | Mosteller | Difference |
|---|---|---|---|
| 175 cm, 70 kg | 1.848 m² | 1.845 m² | 0.2% |
| 180 cm, 80 kg | 1.996 m² | 2.000 m² | 0.2% |
| 165 cm, 65 kg | 1.716 m² | 1.726 m² | 0.6% |
For typical adults the two agree within well under one percent — far smaller than the uncertainty of the method itself.
Where Each One Shines
Du Bois remains the reference standard in much of the research literature, so study protocols sometimes name it explicitly. Mosteller wins on practicality: it is easy to memorize, easy to verify with any calculator, and easy to catch arithmetic errors with. For infants and very small children, neither dominates — Haycock and Boyd were derived with pediatric data, which is why clinicians often reach for them there.
Does the Choice Change a Dose?
Rarely in a meaningful way. On a 100 mg/m² protocol, the 175 cm / 70 kg example above produces 184.5 mg by Mosteller and 184.8 mg by Du Bois — a 0.3 mg difference. Consistency matters more than the choice: institutions standardize on one formula so doses stay comparable over time.
Frequently Asked Questions
Which BSA formula should I use for a school or clinical assignment?
Use whichever the protocol or assignment specifies. If none is named, Mosteller is the common modern default and Du Bois is the classic reference — and showing both with this calculator covers either answer.
Why does Du Bois use fractional exponents?
The exponents 0.425 and 0.725 were fitted to direct surface measurements in 1916. They capture how surface area scales with body size slightly differently than a simple geometric mean.
Are Haycock and Boyd closer to Du Bois or Mosteller?
Both land in the same cluster. For a 175 cm, 70 kg adult, Haycock gives 1.847 m² and Boyd 1.851 m² — all four formulas agree within about 0.4 percent for average adults.
Which formula do electronic health records use?
Many EHR systems default to Mosteller because it is simple and reproducible, but Du Bois is also common. The formula used should appear on the dosing record.