Calculator
Body Surface Area Calculator
Estimate total body surface area (BSA) using the widely taught Mosteller formula.
Body Surface Area Calculator
Enter height and weight to estimate body surface area.
This tool is for education and general interest only. It is not a medical device and must not be used to diagnose, treat or make health decisions. Always consult a qualified professional.
How to use it
- Step 1Enter your height in centimetres.
- Step 2Enter your weight in kilograms.
- Step 3Read your estimated body surface area.
What is body surface area?
Body surface area (BSA) estimates the total external area of the human body. It is measured in square metres and is a useful teaching concept in physiology.
Because BSA scales with both height and weight, it is often used in education to compare people of different sizes more fairly than weight alone.
The Mosteller formula
This tool uses the Mosteller formula, one of the simplest and most popular estimates: the square root of height in centimetres times weight in kilograms, divided by 3600.
The average adult BSA is often quoted as roughly 1.7 square metres, though this varies widely between individuals. Learn more in our skin anatomy guide and metabolism guide.
Questions & Answers
Frequently asked questions
For adults it is often around 1.6–1.9 square metres, but this varies with height and build.
BSA accounts for both height and weight, so it gives a fuller picture of body size than weight alone. It is mainly an educational and clinical teaching measure.
The Mosteller formula, chosen for its simplicity and popularity in teaching.
Understand the science
Go beyond the numbers
Every tool pairs with a guide that explains the biology behind it in plain language.