Plain-language meaning
Body surface area, or BSA, estimates the total external surface of the body from height and weight. It is usually shown in square meters.
Example
The Mosteller formula estimates BSA as the square root of height in centimeters multiplied by weight in kilograms, divided by 3600. A person who is 170 cm and 70 kg has an estimated BSA of about 1.82 m2 with this method.
Where BSA is used
BSA appears in some clinical, physiology and dosing contexts because it can scale differently from body weight alone. A public calculator can show the formula result, but it should not be used to choose medication doses without a qualified clinician.
Limitations
BSA formulas are estimates. Results can differ between formulas, and estimates may be less reliable for infants, very small or very large body sizes, pregnancy or specific clinical situations.
What to check
- Confirm whether the calculator uses Mosteller or another BSA formula.
- Use consistent units: centimeters and kilograms, or a calculator that converts units correctly.
- For any medical decision, use the method required by the clinician, institution or product label.
FAQ
Is BSA the same as BMI?
No. BMI is weight divided by height squared. BSA estimates external body surface area.
Can BSA be used for diagnosis?
No. It is a calculation input used in some contexts, not a diagnosis by itself.