Result
- Mosteller (clinical default)1.845 m²
- Du Bois & Du Bois (1916)1.848 m²
- Mean of both formulas1.846 m²
- Cross-check spreadMosteller and Du Bois agree to ~1% across the normal adult range; >3% spread suggests an out-of-domain input (very small or very obese).0.19 %
How to use this calculator
- Enter weight and height in metric (kg, cm) or imperial (lb, in).
- Read Mosteller BSA as the clinical-default value, with Du Bois as a cross-check.
- Use the mean if your protocol does not specify which formula.
- For chemo or anesthesia dosing, follow your institution's protocol — do not use this calculator unattended.
About this tool
Body surface area (BSA) is a physiologic measurement used for indexing cardiac output, glomerular filtration rate, and certain medication doses (notably chemotherapy and some anesthetics). The most-used clinical formula is Mosteller (1987): BSA = √(weight × height ÷ 3600), with weight in kg and height in cm. The older Du Bois & Du Bois (1916) formula, derived from cadaver measurements, agrees with Mosteller to within about 1% across the normal adult range. This calculator returns both, plus a mean and a cross-check spread that can flag out-of-range inputs. Average adult BSA falls roughly between 1.6 m² (women) and 1.9 m² (men); chemotherapy protocols commonly cap dosing BSA at 2.0–2.2 m² to limit toxicity.
How it works — the formula
BSA(m²) — Mosteller: √(weight(kg) × height(cm) / 3600); Du Bois: 0.007184 × weight(kg)^0.425 × height(cm)^0.725Mosteller (1987) is a simplification published in the New England Journal of Medicine; it agrees with Du Bois to within ~1% in the normal-adult range and is the most-used clinical formula. Du Bois & Du Bois (1916) was derived from nine cadaver measurements and remains the historical reference, especially for cardiac-index normalization. Both inputs are in metric (kg, cm); the calculator converts imperial inputs internally using the exact factors 1 lb = 0.45359237 kg and 1 in = 2.54 cm.
Worked examples
- Inputs:
- weight = 70 kg, height = 175 cm
- Output:
- Mosteller = √(70·175/3600) = √3.4028 ≈ 1.84 m²; Du Bois ≈ 1.85 m²
- Inputs:
- weight = 80 kg, height = 180 cm
- Output:
- Mosteller = √(80·180/3600) = √4.0000 = 2.00 m² exactly; Du Bois ≈ 1.99 m²
- Inputs:
- weight = 60 kg, height = 160 cm
- Output:
- Mosteller = √(60·160/3600) = √2.6667 ≈ 1.63 m²; Du Bois ≈ 1.62 m²
Limitations
- Mosteller and Du Bois were derived from adult populations and substantially underestimate BSA in infants and small children — use Haycock or Mosteller-pediatric for under-2-year-olds.
- Estimates are based on height and weight only; they ignore body composition, hydration state, and amputation. Very obese patients may have overestimated true skin area.
- Chemotherapy and anesthesia dosing follow protocol-specific BSA caps (commonly 2.0–2.2 m²) which are NOT applied here. This calculator returns the physiologic BSA, not a dosing-BSA.
- Cardiac index, GFR, and other indexed values use Du Bois historically; switching to Mosteller can change the indexed value by ~1% — verify which formula your reference range assumes.
For educational reference only. Do not use this calculator as the sole basis for medication dosing — always follow your institution's clinical protocol.