Body Surface Area (BSA) Calculator
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Different formulas give different estimates. No medication dosing is calculated or recommended.
- Takahira (0.007241 variant)
- — m²
- Mosteller (1987)
- — m²
- Fujimoto under 1 year
- — m²
- Fujimoto ages 1–5
- — m²
- Fujimoto age 6+
- — m²
Fujimoto has three age-specific equations. Age is not entered, and no formula is automatically selected. Refer only to the matching group (under 1 / 1–5 / 6+ years).
Undo after clearing is intentionally unavailable to prevent mixing patients measurements.
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Six formulas, populations, and original sources
Inputs and display
Height in cm and weight in kg. All six calculations run from complete and valid inputs. Results are m² to three decimal places, with three significant digits for extremely small nonzero results.
Equations
H = height (cm); W = weight (kg); exponents are powers, not multiplication.
- Du Bois (1916): 0.007184 × H0.725 × W0.425
- Takahira (1925; chosen coefficient variant): 0.007241 × H0.725 × W0.425. The 0.007246 variant is also reported; original coefficient verification is outstanding.
- Mosteller (1987): √(H × W / 3600)
- Fujimoto under age 1 (1968): 0.009568 × H0.655 × W0.473
- Fujimoto ages 1–5: 0.038189 × H0.362 × W0.423
- Fujimoto age 6+ and adults: 0.008883 × H0.663 × W0.444
Fujimoto original coefficients are in cm² and were divided by 10,000 to express m².
Worked examples (hypothetical)
At 170 cm and 65 kg, Du Bois gives 1.754 m²; Mosteller gives 1.752 m²; Fujimoto age 6+ gives 1.707 m². For 50 cm and 3 kg, Fujimoto under 1 gives 0.209 m².
Population and limits
These are estimates, not direct measurements. They are not validated for every age, body composition or disease. Do not use for dosing without a specified and clinically validated method. Takahira coefficient discrepancies have not been fully resolved.
Sources and review
Original references checked 2026-11-10.