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Body Surface Area Calculator

The calculator below computes the total surface area of a human body, referred to as body surface area (BSA). Direct measurement of BSA is difficult, and as such many formulas have been published that estimate BSA. The calculator below provides results for some of the most popular formulas.

Table of average BSAs

	ft²	m²
Newborn child	2.69	0.25
Two-year-old child	5.38	0.5
Ten-year-old child	12.27	1.14
Adult female	17.22	1.6
Adult male	20.45	1.9

BSA is often used in clinical purposes over body weight because it is a more accurate indicator of metabolic mass (the body's need for energy). Metabolic mass can be estimated using fat-free mass, where fat-free mass is all of a person's body mass that does not include fat. This includes bones, tendons, inner organs, muscles, blood, nerves, and more. Since body fat is not metabolically active and fat-free mass excludes body fat, fat-free mass is a reasonable estimate of metabolic mass.

BSA is also used in various other clinical settings, such as determining cardiac index (to relate a person's heart performance to their body size) or most commonly, dosages for chemotherapy (a category of cancer treatment). While dosing for chemotherapy is often determined using a patient's BSA, there exist arguments against the use of BSA to determine medication dosages that have a narrow therapeutic index – the comparison of the amount of a substance necessary to produce a therapeutic effect, to the amount that causes toxicity. If the therapeutic index is too narrow, BSA may not be an accurate enough measure, and there is a risk of causing a toxic rather than therapeutic effect. There is also evidence that BSA becomes less accurate at the extremes of height and weight, and BMI may be a better estimate in such cases. Despite these limitations, the effects of chemotherapy dosages as determined by BSA measurements still remain more consistent than those determined by body weight alone.

Below are some of the most popular formulas for estimating BSA, and links to references for each for further detail on their derivations. The most widely used of these is the Du Bois formula, which has been shown to be effective for estimating body fat in both obese and non-obese patients, unlike body mass index. Where BSA is represented in m², W is weight in kg, and H is height in cm, the formulas are as follows:

Du Bois formula:

BSA = 0.007184 × W^0.425 × H^0.725

Du Bois D, Du Bois EF (Jun 1916). "A formula to estimate the approximate surface area if height and weight be known". Archives of Internal Medicine 17 (6): 863-71. PMID 2520314. Retrieved 2012-09-09.

Mosteller formula:

BSA = = 0.016667 × W^0.5 × H^0.5

Mosteller RD. "Simplified calculation of body-surface area". N Engl J Med 1987; 317:1098. PMID 3657876.

Haycock formula:

BSA = 0.024265 × W^0.5378 × H^0.3964

Haycock GB, Schwartz GJ, Wisotsky DH "Geometric method for measuring body surface area: A height-weight formula validated in infants, children and adults" J Pediatr 1978, 93:62-66.

Gehan and George formula:

BSA = 0.0235 × W^0.51456 × H^0.42246

Gehan EA, George SL, Cancer Chemother Rep 1970, 54:225-235

Boyd formula:

BSA = 0.03330 × W^{(0.6157 - 0.0188 × log10(W)} × H^0.3

Boyd, Edith (1935). The Growth of the Surface Area of the Human Body. University of Minnesota. The Institute of Child Welfare, Monograph Series, No. x. London: Oxford University Press

Fujimoto formula:

BSA = 0.008883 × W^0.444 × H^0.663

Fujimoto S, Watanabe T, Sakamoto A, Yukawa K, Morimoto K. Studies on the physical surface area of Japanese. 18. Calculation formulae in three stages over all ages. Nippon Eiseigaku Zasshi 1968;5:443-50.

Takahira formula:

BSA = 0.007241 × W^0.425 × H^0.725

Schlich formula:

Women BSA = 0.000975482 × W^0.46 × H^1.08

Men BSA = 0.000579479 × W^0.38 × H^1.24

Schlich E, Schumm M, Schlich M: "3-D-Body-Scan als anthropometrisches Verfahren zur Bestimmung der spezifischen Korperoberflache". Ernahrungs Umschau 2010;57:178-183