Body Surface Area Calculator
Calculate body surface area (BSA) with the Mosteller and Du Bois formulas.
Results update as you type.
About this calculator
A body surface area (BSA) calculator estimates the total external area of your body in square metres from your height and weight. BSA is widely used in medicine to scale drug doses and physiological measurements. This tool uses the simple Mosteller formula and shows the classic Du Bois result for comparison.
Frequently asked questions
What is the Mosteller BSA formula?
BSA (m²) = square root of (height in cm × weight in kg ÷ 3600). It is the most common formula because it is easy to compute yet closely matches more complex equations.
Why is body surface area used in medicine?
Many drug doses — especially chemotherapy — and measures like cardiac index are scaled to BSA rather than weight, because surface area tracks metabolic rate more closely than body mass alone.
Results are estimates for general guidance only, not financial, medical or tax advice.