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What Is Body Surface Area?
Body Surface Area (BSA) is a measure of the total surface area of your body. Doctors use it to understand things like how your body processes certain medicines, how much fluid your body needs, or how your heart and kidneys are working — because these often relate to your body size more accurately than weight alone.
How to Use This Calculator
Enter your weight and height in the units you prefer (kg or lb, cm or ft/in), then click "Calculate." Your result will appear in square meters (m²).
What Does Your Result Mean?
Most healthy adults have a BSA between 1.6 and 2.0 m². Your number simply reflects your body size — it isn't a diagnosis, and a higher or lower number isn't automatically good or bad.
Why Is BSA Used?
BSA is used in medicine because many body processes (like blood flow, metabolism, and fluid balance) scale more closely with body surface area than with weight alone. Doctors sometimes use it to guide medicine dosing, especially in situations like chemotherapy.
Important note: This calculator gives an estimate for informational purposes only. It should not be used to decide your own medicine dose. Always follow your doctor's or pharmacist's advice.
When Should You Speak With a Healthcare Professional?
If you're asking about BSA because of a specific health condition, medicine dosage, or a doctor's instructions, speak with your healthcare provider — they'll consider your BSA along with your full medical history.
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Frequently Asked Questions
What is a normal BSA value for adults?
Most healthy adults have a BSA between 1.6 and 2.0 m², though this varies naturally with height and weight. There is no single "ideal" number — BSA simply reflects body size.
How is BSA calculated for children?
The same Mosteller formula is used for children as for adults — it's validated across pediatric and adult populations. Just enter the child's height and weight as usual.
Why is BSA used in medicine instead of weight alone?
Many body processes — like blood flow, metabolism, and drug clearance — correlate more closely with body surface area than with weight alone, making BSA a more precise reference in certain clinical calculations.
What's the difference between BSA and BMI?
BMI (Body Mass Index) estimates body fat based on height and weight. BSA estimates the total surface area of the body. They measure different things and are used for different clinical purposes.
Is this BSA calculator accurate enough for medication dosing?
This calculator is intended for educational and reference purposes. For actual medication dosing, always follow your doctor's or pharmacist's calculation based on your institution's specific protocol.