acalculator

What is my BSA (body surface area)?

Enter your height and weight to calculate your body surface area (BSA) in square meters by the Mosteller and Du Bois formulas. For information only. This is not medical advice or a diagnosis. Do not use it to make treatment decisions without a clinician. No licensed clinician has reviewed this page.

Your numbers

Units
BSA (Mosteller)
2.01

The body surface area is 2.01 m² by the Mosteller formula and 2 m² by the Du Bois formula.

BSA (Du Bois)
2

BSA (Mosteller): 2.01. The body surface area is 2.01 m² by the Mosteller formula and 2 m² by the Du Bois formula.

This calculator gives general information only. It is not medical advice and does not replace a doctor or other health care provider. Talk with a professional about your results. Terms of use

How to calculate

Calculates body surface area (BSA) in square meters from height and weight with the Mosteller formula and the Du Bois formula.

Example with the default inputs (Height 5 ft 10 in, Weight 180 lb): The body surface area is 2.01 m² by the Mosteller formula and 2 m² by the Du Bois formula.

Method: Mosteller: BSA (m²) = √(height in cm × weight in kg ÷ 3600). Du Bois: BSA (m²) = 0.007184 × weight^0.425 × height^0.725.

  • Height in centimeters and weight in kilograms; pounds and feet are converted exactly (1 lb = 0.45359237 kg, 1 in = 2.54 cm).
  • Each area is rounded to 2 decimals, halves up.
  • Both formulas estimate the skin area; neither was built for extreme body sizes.

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. Height 5 ft 6.9 in, Weight 154.3 lb gives BSA (Mosteller) 1.82, BSA (Du Bois) 1.81.Source: Mosteller 1987: √(170 × 70 ÷ 3600) = 1.8181; Du Bois 1916: 0.007184 × 70^0.425 × 170^0.725 = 1.8097
  2. Height 5 ft 10 in, Weight 180 lb gives BSA (Mosteller) 2.01, BSA (Du Bois) 2.
  3. Height 3 ft 7.3 in, Weight 39.68 lb gives BSA (Mosteller) 0.74, BSA (Du Bois) 0.74.
  4. Height 5 ft 3 in, Weight 110.2 lb gives BSA (Mosteller) 1.49, BSA (Du Bois) 1.5.

Medical disclaimer

This calculator is for information and education only. It is not medical advice, and its result is not a diagnosis. Do not use it to start, stop, or change a treatment without a clinician who knows your health history. No licensed clinician has reviewed this page. This site's editors checked the formulas and worked examples against published sources. If you think you have a medical emergency, call your local emergency number.

When this does not apply. The Mosteller (1987) and Du Bois (1916) formulas estimate skin area for people of ordinary build. They are rough at extremes of weight or height and in newborns. A BSA is not a dose: a dose based on BSA comes from a prescriber.

How BSA is worked out

With height H in centimeters and weight W in kilograms:

  • Mosteller (1987): BSA = √(H × W ÷ 3600)
  • Du Bois and Du Bois (1916): BSA = 0.007184 × W^0.425 × H^0.725

Both give square meters (m²). Heights in feet and inches and weights in pounds are converted first (1 in = 2.54 cm, 1 lb = 0.45359237 kg). Each result is rounded to 2 decimal places, halves up, read from the decimal value (a result within 1e-9, relative, of a half counts as the half).

Inputs the calculator accepts

Height 30 to 250 cm, weight 1 to 350 kg. Both formulas were made for people of ordinary build, so results at the extremes are rough.

Worked examples by hand

170 cm, 70 kg. Mosteller: 170 × 70 = 11,900; ÷ 3,600 = 3.3056; √3.3056 = 1.82 m². Du Bois: 70^0.425 = 6.0837, 170^0.725 = 41.407; 0.007184 × 6.0837 × 41.407 = 1.81 m² (1.8097).

5 ft 10 in, 180 lb (177.8 cm, 81.647 kg). Mosteller: √(177.8 × 81.647 ÷ 3,600) = √4.0324 = 2.01 m². Du Bois: 2.00 m² (1.9959).

A child, 110 cm and 18 kg. Mosteller: √(1,980 ÷ 3,600) = √0.55 = 0.74 m². Du Bois: 0.74 m² (0.7411).

160 cm, 50 kg. Mosteller: √(8,000 ÷ 3,600) = √2.2222 = 1.49 m². Du Bois: 1.50 m² (1.5011).

Other questions people ask

What is body surface area?

Body surface area (BSA) is an estimate of the total area of the skin, in square meters (m²). An adult is usually between 1.6 and 2.0 m². Doctors use it to scale some drug doses, such as chemotherapy, and to index measures such as cardiac output and kidney function to body size.

Which BSA formula is best?

The Mosteller formula is the most widely used because it is simple: the square root of height in cm times weight in kg, divided by 3,600. The Du Bois formula (1916) is the oldest. For most adults the two differ by less than 0.05 m². The formula your clinic uses is the one to follow.

How do I calculate BSA by hand?

Multiply your height in centimeters by your weight in kilograms, divide by 3,600, and take the square root. For 170 cm and 70 kg: 170 × 70 = 11,900; 11,900 ÷ 3,600 = 3.306; √3.306 = 1.82 m².

Can I use pounds and inches?

Yes. The calculator converts exactly: 1 inch is 2.54 cm and 1 pound is 0.45359237 kg. The formulas themselves use centimeters and kilograms.