Body Surface Area (BSA) Calculator
Calculate your body surface area using the Mosteller formula — a measure used in medicine for drug dosing, physiology and clinical assessment.
What is body surface area?
Body surface area (BSA) is the total surface area of the human body, expressed in square metres. Because it relates more closely to metabolic rate and organ size than body weight alone, it is widely used in medicine. The average adult has a BSA of around 1.7 square metres. This calculator uses the Mosteller formula, which is the most commonly used equation because it is simple, accurate and easy to compute from just height and weight.
Why BSA is used in medicine
Many physiological processes scale with surface area rather than weight, which is why BSA is used in several clinical contexts. It is most well known for calculating doses of certain medications, particularly chemotherapy drugs, where precise dosing is critical. BSA is also used to index measurements like cardiac output and kidney function, and to estimate fluid requirements in burns. Using BSA helps tailor treatment to body size more accurately than weight alone.
The Mosteller formula
The Mosteller formula calculates BSA as the square root of height in centimetres multiplied by weight in kilograms, divided by 3600. Its simplicity made it popular in clinical practice, and studies have shown it to be as accurate as more complex equations for most people. This calculator handles the unit conversions for you, so you can enter your measurements in either metric or imperial.
Interpreting your result
A typical adult BSA ranges from about 1.5 to 2.0 square metres, with 1.7 often cited as the average. Children naturally have smaller values. Your BSA is mainly a clinical reference rather than a fitness or health metric — it does not tell you whether you are a healthy weight. If a healthcare provider uses your BSA for dosing or assessment, they will calculate it precisely as part of your care. This tool is for educational reference.
Frequently Asked Questions
The average adult body surface area is about 1.7 square metres, though it varies with height and weight, typically ranging from around 1.5 to 2.0 square metres in adults. Children have smaller values. BSA is a clinical reference measure rather than a health indicator.
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Sources & References
- 1.Mosteller RD.. Simplified calculation of body-surface area. New England Journal of Medicine.
- 2.Du Bois D, Du Bois EF.. A formula to estimate the approximate surface area if height and weight be known.
- 3.StatPearls / NCBI. Body Surface Area.
LifeCheckIQ content is based on peer-reviewed research, recognised clinical guidelines, and authoritative medical sources, and is reviewed by Deborah Adotso, General Nurse, for clinical accuracy.
Medical Disclaimer: This tool is for informational and educational purposes only. Results are not a medical diagnosis. Always consult a qualified healthcare professional for medical advice, diagnosis, or treatment. In an emergency, call your local emergency number or visit the nearest hospital immediately.