Body-surface area

The body-surface area (BSA) — that is, more precisely, the surface area of a human body or, equivalently, the size of its skin — is a physiological measure used in medicine. On the average, the body-surface area is 1.7 m² (1.9 m² for men and 1.6 m² for women).

A common estimate is given by the Mosteller formula:

${\text{BSA}}(\mathrm {m} ^{2})={\sqrt {{\text{weight}}(\mathrm {kg} )\times {\text{height}}(\mathrm {cm} ) \over 3600}}={\sqrt {{\text{weight}}(\mathrm {lb} )\times {\text{height}}(\mathrm {in} ) \over 3131}}$

Remark: Conversion of metric to English units or vice-versa shows that the two formulas are not equivalent. However, the difference is far below the expected error of the estimate and is therefore negligible. The numbers 3600 and 3131 have probably been chosen for mnemonic reasons.