Body Surface Area Calculator

The medical reference standard BSA is 1.73 m², which most clinical protocols use as a normalisation factor. In practice, the average adult female BSA is approximately 1.6 m² and the average adult male BSA is approximately 1.9 m². These are averages — your individual BSA depends on your specific height and weight.

No single formula is universally superior. The Mosteller formula is the most widely used in clinical practice today because of its simplicity and reasonable accuracy across typical adult body sizes. The Haycock formula is considered more accurate for children and small adults. The DuBois formula, the original standard from 1916, remains common in pharmacokinetic research. For general purposes, an average of multiple formulas provides a reliable consensus estimate.

Body weight alone does not account for differences in body composition, plasma volume, and drug clearance between individuals. BSA more closely correlates with cardiac output, extracellular fluid volume, and renal clearance — all of which influence how the body distributes and eliminates cytotoxic drugs. BSA-based dosing reduces the coefficient of variation in drug exposure, improving both safety and efficacy. However, BSA dosing is not perfect, and some centres cap doses at a maximum BSA (often 2.0 m²) to prevent toxicity in larger-bodied patients.

Yes — since BSA is calculated from both weight and height, any change in body weight changes BSA. A 10 kg weight change in an adult of average height typically changes BSA by approximately 0.05–0.10 m². In oncology, BSA is often recalculated at each treatment cycle to reflect weight changes due to disease progression or treatment side effects.

BMI (Body Mass Index) = weight (kg) ÷ height² (m²). It is a simple screening ratio used to classify body weight relative to height but does not measure body surface area. BSA is the actual estimated external surface area of the body in square metres. BMI is used for population health screening; BSA is used for clinical dose calculations and physiological normalisation.

No. Drug dosing — especially for chemotherapy — must be performed by a qualified oncologist, pharmacist, or clinical team using verified BSA values, dosing protocols, organ function assessments, and safety checks. This calculator is for educational and informational purposes only. Never self-administer or adjust medications based on a BSA calculated with this tool.