Body surface area is used in medicine to calculate doses of chemotherapy drugs, to assess cardiac output, and to adjust other clinical measurements for body size. This tool uses the Mosteller formula, one of several in clinical use.
BSA (m²) = √(height (cm) × weight (kg) / 3600). Mosteller's formula is valued for being simple enough to calculate by hand while remaining among the more accurate options — it's one of the most widely used BSA formulae in clinical practice today, alongside others such as Du Bois & Du Bois and Haycock.
Many chemotherapy drug doses are prescribed per m² of body surface area rather than by weight alone, since BSA correlates more closely with metabolic rate and organ function across a wide range of body sizes. It's also used to index cardiac output (cardiac index) and other measurements that need to be compared fairly between people of different sizes.
Different BSA formulae produce different results for the same height and weight — confirm which formula your local protocol requires before using this figure for dose calculation. This tool is for clinical decision support only and is not a substitute for clinical judgement.
Mosteller RD. "Simplified calculation of body-surface area." N Engl J Med. 1987;317(17):1098. PubMed: PMID 3657876.