How to use the body surface area calculator
- Choose Centimeters, kg or Inches, pounds for the units you have.
- Enter your height and weight. The page converts inches and pounds for you.
- Read the headline for the Mosteller value in square meters, then compare the Du Bois and Du Bois and Haycock values below it.
- Use Copy, Print or CSV to keep the three estimates together with the measurements they came from.
Formula
Mosteller = square root of (height in cm x weight in kg / 3600)
Du Bois and Du Bois = 0.007184 x weight^0.425 x height^0.725
Haycock = 0.024265 x weight^0.5378 x height^0.3964
Height is in centimeters and weight in kilograms in every formula, and the answer is in square meters. Inches are multiplied by 2.54 and pounds by 0.45359237 first. Results are shown to two decimals; the steps show four.
170 cm and 70 kg
Mosteller multiplies the height and weight (170 x 70 = 11,900), divides by 3,600 to get 3.3056, and takes the square root: 1.8181 square meters, shown as 1.82.
The Du Bois and Du Bois formula gives 1.8097 and the Haycock formula gives 1.8257 for the same person, so all three agree to within about 0.02 square meters. Converted to square feet, 1.8181 square meters is about 19.57.
What the number is and is not
Body surface area is the estimated area of the outside of the body. Several fields use it to scale a quantity to body size, which is why more than one formula exists. The formulas are fitted to measurements of groups of people, so they estimate surface area from two numbers and do not measure it.
The three results are close for adults of ordinary build and drift apart for very small or very large bodies. When the formulas disagree, that spread is itself a reminder that the figure is an estimate.
Safety and limits
This page is general information. Do not use it to calculate a medication dose, a treatment amount or any other figure that affects care. Clinicians choose a formula and rounding rule that suit the situation, and they work from measured values.
To compare body size in another way, the BMI calculator uses the same two inputs, and the lean body mass calculator estimates how much of the weight is lean.
Assumptions and limits
- Height is 30 to 272 cm (12 to 107 inches) and weight is 2 to 650 kg (4.5 to 1,430 pounds). Values outside those ranges are rejected.
- All three formulas are published approximations. They are not measurements and they can differ from each other.
- No dosing, treatment or health thresholds are built in, and nothing here is medical advice.
- Your numbers stay in your browser and are not sent anywhere.
Frequently asked questions
What is the Mosteller formula for body surface area?
Mosteller takes the square root of height in centimeters times weight in kilograms, divided by 3,600. For 170 cm and 70 kg that is the square root of 3.3056, or 1.82 square meters.
Why does the page show three formulas?
Several formulas are in use and they give slightly different answers, so showing Mosteller, Du Bois and Du Bois, and Haycock together lets you see how much the choice matters for your measurements.
Can I use this to work out a medication dose?
No. This page is for general information only. Doses must come from a clinician or pharmacist who uses measured values and the right method for that medicine.
How do I convert square meters to square feet?
Multiply by 10.7639. The page shows the Mosteller result in square feet for you, so 1.8181 square meters is about 19.57 square feet.