Body Surface Area Calculator
Enter height and weight to calculate body surface area (BSA), commonly used for medication dosing.
Last updated: September 5, 2026
Frequently asked questions
What is body surface area (BSA) used for?
Primarily for dosing certain medications (especially chemotherapy drugs) more precisely than weight alone, since some drug effects correlate better with total body surface area than with body mass.
What is the Mosteller formula?
BSA = √((height in cm × weight in kg) ÷ 3600) - a simple, widely used formula that closely approximates the more complex DuBois formula while being much easier to calculate by hand.
What is a typical BSA for an adult?
About 1.5 to 2.0 m² for most adults, though it varies with height and weight - a person of average height (170cm) and weight (70kg) has a BSA of roughly 1.81 m² by the Mosteller formula.
Should I use this to calculate my own medication dose?
No - this is a general reference calculation. Medication dosing based on BSA should always be determined and verified by a qualified healthcare provider, since dosing also depends on the specific drug, your medical history, and other clinical factors this calculator doesn't account for.
What's an example BSA calculation?
For someone 180 cm tall weighing 80 kg: BSA = √((180 × 80) ÷ 3600) = √4 = 2.0 m². That's on the higher end of the typical adult range.
How does BSA differ from BMI?
BMI (weight ÷ height²) is a screening tool for weight status relative to height, while BSA estimates total skin surface area and is used mainly for medical dosing and physiological measurements like cardiac index - they answer different questions and aren't interchangeable.
Does the Mosteller formula work the same for children as adults?
Yes - the Mosteller formula uses the same equation regardless of age, since it's based purely on height and weight rather than age-specific constants. This makes it a common choice in pediatric dosing calculations as well as adult ones.