Body Surface Area Calculator
Body surface area scales drug doses and burn estimates to the person rather than to a flat number. Height and weight are all it takes, and the Mosteller formula is the clinical standard.
Body surface area
1.8181
- Du Bois estimate
- 1.3868
- Haycock estimate
- 1.8257
- In square feet
- 19.57
- Dose at this rate
- 181.81
Values update as you type. This calculator covers the single scenario its formula assumes — see Common Mistakes for what it leaves out.
The formula this calculator uses
BSA = sqrt( height in cm x weight in kg / 3600 )
- BSA
- Body surface area, in square metres
- height
- Height in centimetres
- weight
- Weight in kilograms
- 3600
- The constant that converts the units to square metres
How to check the result by hand
- 1
Get height and weight in metric units
Height must be in centimetres and weight in kilograms. A 170 centimetre adult weighing 70 kilograms needs no conversion.
- 2
Multiply height by weight
170 times 70 is 11900. This product has no physical meaning on its own; it is only the input to the next step.
- 3
Divide by 3600 and take the square root
11900 divided by 3600 is 3.305556, and its square root is 1.8181 square metres. That is the Mosteller estimate.
- 4
Cross-check against the other formulas
Du Bois gives 1.3868 and Haycock gives 1.8257. A result well outside that spread suggests a unit conversion error.
For worked examples, common mistakes and the limits of this formula, read the full How To Calculate Body Surface Area page.