This calculator estimates body surface area (BSA) from height and weight using eight common formulas — Du Bois, Mosteller, Haycock, Gehan & George, Boyd, Fujimoto, Takahira, and Schlich — and also reports BMI. Direct measurement of skin area is impractical, so these equations are the everyday clinical shortcuts. Results are estimates for education and fitness context, not a diagnosis or a dosing tool on their own.
Choosing an equation
Haycock's study included subjects from premature infants through adults and reported that Du Bois increasingly underestimated surface area below 0.7 m². Mosteller is easy to reproduce by hand. Other equations may be required by a particular protocol or retained to compare with historical results. The table shows the equations side by side rather than declaring one universally correct.
Examples
Man, 5 ft 9 in, 155 lb (US default)
Height is 175.26 cm and weight is 155 × 0.453592 kg. Du Bois is 1.85 m² (19.95 ft², 2,873 in²). Mosteller is also 1.85 m²; Haycock 1.85; Gehan & George and Boyd 1.86; Fujimoto 1.80; Takahira 1.87; Schlich 1.77. BMI is 22.9.
Man, 175 cm, 70 kg (metric)
Du Bois is 1.85 m² (19.89 ft²). Mosteller is 1.84 m². The other adult formulas sit between 1.76 m² (Schlich) and 1.86 m² (Takahira). Fujimoto is 1.80 m². BMI is 22.9.
Newborn, 50 cm, 3.5 kg (or 3,500 g)
Du Bois is 0.21 m² (2.25 ft²), while Mosteller and Haycock are about 0.22 m². Metric grams and kilograms give the same result when the weight is equivalent. Formula choice matters more at this small body size.
Formula
Every formula below uses weight W in kilograms and height H in centimetres and returns BSA in m². US pounds convert with the rounded factor of 0.453592 kg/lb. Square feet and square inches use the international foot (1 ft = 0.3048 m).
Du Bois
BSA = 0.007184 × W^0.425 × H^0.725
Mosteller
BSA = 0.016667 × W^0.5 × H^0.5
Haycock
BSA = 0.024265 × W^0.5378 × H^0.3964
Gehan and George
BSA = 0.0235 × W^0.51456 × H^0.42246
Boyd
BSA = 0.03330 × W^(0.6157 − 0.0188 × log10(W)) × H^0.3
Fujimoto
BSA = 0.008883 × W^0.444 × H^0.663
Takahira
BSA = 0.007241 × W^0.425 × H^0.725
Schlich
Women: BSA = 0.000975482 × W^0.46 × H^1.08
Men: BSA = 0.000579479 × W^0.38 × H^1.24
Fujimoto uses the published 0.008883 coefficient. This intentionally does not copy a competing calculator's lower live coefficient. Mosteller is algebraically the familiar sqrt(W × H / 3600) form.