Body Surface Area Calculator
Calculate your Body Surface Area (BSA) using the Mosteller formula. Important for medical dosing and health assessments.
What is Body Surface Area?
Body Surface Area (BSA) is the measured or calculated surface area of a human body. Expressed in square meters (m²), BSA is used in medical dosing for chemotherapy, immunosuppressants, and other medications—more accurate than weight-based dosing. The Mosteller formula: BSA = √((height × weight)/3600) is the most widely used, simple to calculate, and highly accurate. Average adult BSA ranges from 1.5-2.0 m². BSA increases with weight and height. Using body weight alone for medication dosing can lead to errors, especially in obese patients where BSA is more appropriate. In fitness and nutrition, BSA helps estimate metabolism and caloric needs more accurately than weight alone. Children have proportionally higher BSA relative to weight, which is why pediatric dosing differs from adults. Regular monitoring of BSA helps track changes in body composition. BSA is calculated automatically in most medical settings, but understanding it helps patients appreciate its importance in personalized medicine and optimal treatment planning.