Body Surface Area Calculator
0.00 m² body surface area
How Body Surface Area Is Calculated
This calculator uses the Mosteller formula, the version most widely used in clinical practice today because it's simple and matches more complex formulas closely across most body sizes: BSA (m²) = square root of [height (cm) × weight (kg) ÷ 3600]. For reference, the results also show the value from the older DuBois & DuBois formula (BSA = 0.007184 × weight(kg)0.425 × height(cm)0.725), which was derived from a small 1916 study but is still cited in some drug-dosing literature. The two formulas typically agree within a few hundredths of a square meter.
Why BSA Matters
Body surface area is used mainly to dose medications (especially chemotherapy agents) and to normalize measurements like cardiac output or kidney function so they can be compared fairly between people of different sizes — this is also why BSA shows up alongside estimated GFR (kidney function) calculations. Unlike BMI, which is a simple weight-to-height ratio used for population-level screening, BSA is meant to approximate total skin surface area and is used in very different clinical contexts.
A Note on Accuracy
Every BSA formula is an estimate based on population averages, not a direct measurement of your actual body surface — actual clinical dosing decisions account for other individual factors as well. This tool is for general educational and reference purposes only, not medical advice; always follow your doctor's or pharmacist's specific dosing guidance rather than a number from a calculator.
Frequently Asked Questions
What is body surface area (BSA) used for?
BSA is primarily used in medicine to calculate drug dosages (especially chemotherapy) and to normalize measurements like cardiac output or kidney function so they can be compared fairly across people of different body sizes.
Why does this calculator show two different BSA numbers?
The main result uses the Mosteller formula, the simplest and most commonly used method in modern clinical practice. The DuBois & DuBois formula is shown for reference since it's an older, more complex formula still cited in some dosing literature; the two typically agree within a few hundredths of a square meter.