Body Surface Area Calculator
Enter your height in centimeters and your weight in kilograms, then press Calculate BSA. The calculator shows your body surface area (BSA) in square meters by three published formulas side by side: Du Bois, Mosteller and Haycock. Doctors use BSA to dose some drugs, many chemotherapy drugs among them, and to scale heart measurements such as the cardiac index.
How to use the Body Surface Area Calculator
- Enter your numbers in the Body Surface Area Calculator above.
- Press the Calculate BSA button to see the result.
- To try other numbers, change any value and press the button again.
The BSA formulas
Du Bois: BSA = 0.007184 × H^0.725 × W^0.425 · · · Mosteller: BSA = √((H × W) / 3600) · · · Haycock: BSA = 0.024265 × H^0.3964 × W^0.5378
H is height in cm, W is weight in kg and BSA comes out in m². Du Bois and Du Bois published their formula in 1916, Haycock, Schwartz and Wisotsky theirs in 1978, and Mosteller proposed the square-root form in 1987 as one that is easy to work out by hand. The calculator rounds each result to 3 decimals. It takes heights from 10 to 300 cm and weights from 0.1 to 1,000 kg.
Worked example
A 75 kg adult at 178 cm. Mosteller: BSA = √((178 × 75) / 3600) = √3.708 ≈ 1.926 m². Du Bois: 0.007184 × 178^0.725 × 75^0.425 ≈ 1.927 m². Haycock: 0.024265 × 178^0.3964 × 75^0.5378 ≈ 1.93 m². For this adult the three agree to within 0.2%.
Frequently asked questions
What is BSA used for?
Mostly for dosing drugs, many chemotherapy drugs among them, and for scaling heart measurements: the cardiac index is cardiac output divided by BSA.
Are the formulas interchangeable?
For an average adult they come out close: 1.927, 1.926 and 1.93 m² for 178 cm and 75 kg. They drift apart at the extremes. For a newborn of 50 cm and 3.5 kg the calculator shows 0.209 m² by Du Bois, 0.22 by Mosteller and 0.224 by Haycock, about 7% between the lowest and the highest. If a dose depends on it, use the formula your clinic uses.
Does BSA change with weight loss?
Yes, but by less than the weight. At the same height, BSA moves with weight to the power 0.425 in Du Bois, 0.5 in Mosteller and 0.5378 in Haycock. A 10% weight loss takes BSA down by about 4.4%, 5.1% and 5.5% by those formulas. Drugs dosed by BSA may need a new dose.