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
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), where metabolic mass can be estimated as fat-free mass since body fat is not metabolically active.1 BSA is used in various clinical settings such as determining cardiac index (to relate a person’s heart performance to their body size) or 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.
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:
1. Greenberg, JA., Boozer, CN. 1999. “Metabolic mass, metabolic rate, caloric restriction, and aging in male Fischer 344 rats.” Elsevier 113(2000): 37-48