Body Surface Area Calculator

Body Surface Area (BSA) is a critical measurement in clinical medicine used to calculate drug dosages, particularly for chemotherapy, cardiac output indexing, and burn surface area assessment. Unlike body weight alone, BSA accounts for both height and mass, providing a more accurate scaling factor for physiological processes such as kidney filtration rate and liver metabolism — the organs responsible for processing most medications. The Mosteller formula is the most widely adopted BSA calculation method in clinical practice worldwide due to its balance of simplicity and accuracy. Oncologists use BSA to dose chemotherapy agents like carboplatin and paclitaxel. Cardiologists use it to compute the Cardiac Index (cardiac output per square meter of BSA). Pediatric clinicians rely on it heavily because children's organ function scales better with surface area than with weight. The average BSA for an adult male is approximately 1.9 m² and for an adult female approximately 1.6 m², though these vary considerably with individual body dimensions.

The Mosteller formula is: BSA (m²) = √(height(cm) × weight(kg) ÷ 3600). The denominator 3600 is derived from converting the formula's original expression in centimeters and kilograms into square meters: since 1 m = 100 cm, one square meter = 10,000 cm², and the formula's internal constant of 0.016667 multiplied through yields the simplified ÷ 3600 form. As a worked example: a person 170 cm tall weighing 70 kg has BSA = √(170 × 70 ÷ 3600) = √(11900 ÷ 3600) = √3.3056 ≈ 1.818 m². The formula was proposed by R.D. Mosteller in 1987 and validated against direct measurements across diverse patient populations. It slightly overestimates BSA for obese individuals compared to more complex formulas (such as DuBois or Haycock), but its simplicity and clinical acceptance make it the preferred method in most hospital pharmacies and oncology treatment protocols.