Body Surface Area (BSA) Calculator

Table of average BSAs

Understanding Body Surface Area (BSA)

Body Surface Area (BSA) is a crucial measurement in clinical settings, often favored over simple body weight due to its enhanced accuracy in reflecting metabolic mass. Metabolic mass, estimated by fat-free mass (all body mass excluding fat), encompasses vital components like bones, organs, muscles, and blood. Our BSA Calculator utilizes established formulas to provide precise estimations for your needs.

Why BSA Matters in Clinical Practice

BSA plays a pivotal role in various clinical applications, including:

Chemotherapy Dosage:

• BSA is widely used to determine appropriate dosages for chemotherapy, ensuring effective treatment while minimizing toxicity. However, it’s important to acknowledge that some argue against its use for medications with a narrow therapeutic index, where even slight dosage variations can have significant consequences. Despite these arguments, BSA remains a more consistent measure than body weight alone.

Cardiac Index:

• BSA is essential for calculating the cardiac index, which relates a patient’s heart performance to their body size, providing valuable insights into cardiovascular health.

Metabolic Mass Estimation:

• Because fat tissue is not metabolicly active, BSA is a more accurate way to measure the metabolic mass of a person. This is important for many medical procedures.

Formulas for Estimating BSA

Our calculator provides estimations based on the following widely recognized formulas:

Du Bois Formula:

• BSA = 0.007184 × W^0.425 × H^0.725
• This is the most widely used formula, proven effective for both obese and non-obese patients.
• 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
• 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.

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

Limitations and Considerations

While BSA is a valuable tool, it’s essential to acknowledge its limitations:

Accuracy at Extremes:

• BSA may become less accurate at the extremes of height and weight. In such cases, BMI or other measures may provide a more reliable estimation.

Therapeutic Index:

• When certain medications with narrow therapeutic index are being dosed, extra caution should be taken. It is possible that BSA is not accurate enough.