American journal of physiology. Regulatory, integrative and comparative physiology
23 Apr 2026 Human body surface area scales linearly with height and mass and is largely independent of body composition: A 3D laser scanning and body composition studyBody surface area is fundamental to clinical medicine, underpinning drug dosing in oncology and pediatrics and normalizing physiological variables such as cardiac output and glomerular filtration rate. Despite over a century of use, most body surface area equations adopt power-law forms derived empirically with little explicit biological justification, and whether body composition data improve prediction has remained unclear. Here, we used high-resolution three-dimensional laser scanning to measure body surface area and dual-energy x-ray absorptiometry (DXA) to measure body composition in 106 healthy adults spanning a wide range of ages, body sizes, and demographic features. Notably, simple linear models predicted body surface area as accurately as complex power-law or body composition-aware formulations: according to sex-specific linear regression, body surface area changes by about 100-115 cm2 per kilogram of body mass and about 70-80 cm2 per centimeter of body height, with no substantial improvement from including lean, fat, or bone mineral mass as separate predictors within the anthropometric range studied. These findings suggest that the long-standing reliance on allometric power-law equations reflects historical convention rather than biological necessity, and that simple linear formulas may suffice for clinical body surface area estimation within the range of body sizes studied here.
