A worked example: 70kg, 170cm
A person weighing 70kg at 170cm tall has a body surface area of 1.81 m² — a figure inside the typical adult range of roughly 1.6 to 2.0 m².
The formula: BSA = 0.007184 × weight^0.425 × height^0.725
Both weight and height are raised to their own specific fractional exponent — not simply multiplied together — reflecting that surface area doesn't scale in direct proportion to either measurement alone. These exact exponents were empirically fitted from body-surface measurements taken on a small group of subjects back in 1916, and have remained in wide clinical use ever since.
A smaller frame: 50kg, 155cm
A smaller person at 50kg and 155cm has a BSA of 1.47 m² — noticeably below the 70kg/170cm example, since both a lower weight and a shorter height each independently pull the result down.
What body surface area is actually used for
BSA is used to calculate medication dosages — especially chemotherapy — and to normalize physiological measurements like cardiac output so people of very different sizes can be meaningfully compared on the same scale.
Why a century-old formula is still the clinical standard
Despite newer BSA formulas being proposed since 1916, the original Du Bois equation remains the most widely used in clinical dosing contexts — familiarity and decades of established dosing protocols built around it outweigh the small accuracy gains newer formulas offer.