Body Surface Area Calculator

Estimate body surface area using common formulas like Mosteller, Du Bois, Haycock, Gehan and George, and Boyd. This free BSA calculator supports US and metric units and shows multiple body surface area estimates in one place.

Calculate Body Surface Area

Using height in feet and inches and weight in pounds.
Using height in centimeters and weight in kilograms.
Your result will appear here.

How body surface area is estimated

Mosteller formula:
BSA = √((height in cm × weight in kg) ÷ 3600)

Du Bois formula:
Uses exponents on height and weight to estimate body surface area.

Haycock, Gehan and George, and Boyd:
These formulas also use body weight and height with slightly different assumptions.

Average estimate:
This calculator also shows the average of the formulas for a simple midpoint reference.

Why body surface area matters

Body surface area is used in a variety of health and clinical settings, including medication dosing, medical assessments, and body-size comparisons.

It can sometimes give a more useful body-size reference than weight alone.

What your result means

Your result shows body surface area estimates from several common formulas. It also gives an average BSA estimate so you can compare methods more easily.

This gives a broader reference instead of relying on only one formula.

Body surface area calculator tips

Frequently asked questions

What is body surface area?

Body surface area is an estimate of the total external surface of the human body, usually expressed in square meters.

Why are there several BSA formulas?

Different formulas were developed using different datasets and methods, so they can produce slightly different estimates.

Which BSA formula is used most often?

Mosteller is one of the most widely used formulas because it is simple and practical.

Is body surface area the same as BMI?

No. BMI estimates weight relative to height, while BSA estimates external body surface area.