Calculate Du Bois body surface area from height and weight or reverse-solve either measurement, with metric and imperial units plus a Mosteller comparison.
Medical notice: For informational use only. Do not use this calculator to dose chemotherapy, prescription medicines, or IV fluids—dosing must be determined and verified by a licensed clinician/pharmacist using the specific protocol. BSA methods and rounding rules vary (e.g., Du Bois, Mosteller, Haycock), and results may be less reliable in situations such as children, pregnancy, kidney/liver disease, severe obesity/edema, amputation, burns, dehydration, or critical illness.
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Du Bois BSA Formula
The Du Bois BSA calculator uses the Du Bois formula to estimate body surface area from weight and height. The formula requires weight in kilograms and height in centimeters.
- BSA = body surface area in square meters, m²
- W = weight in kilograms, kg
- H = height in centimeters, cm
When you enter weight in pounds, the calculator first converts pounds to kilograms.
When you enter height in another unit, the calculator converts it to centimeters before applying the Du Bois formula.
For mixed feet and inches, first combine them as total inches (5 ft 10 in = 70 in), then select inches. The conversion is:
The results show BSA in both square meters and square feet. Reverse modes also accept BSA in either unit.
- BSA mode uses height and weight in the selected units.
- Reverse modes solve the same equation for height or weight from a positive Du Bois BSA and the other measurement. They are mathematical inverses, not measurements or goals.
- Comparison shows Mosteller BSA, the signed difference relative to Mosteller and unclassified BMI. These do not establish clinical accuracy.
Interpreting a Body Surface Area Estimate
BSA alone does not classify health or define a normal target. The calculator estimates surface area from height and weight; it does not measure it. Formula choice, body composition, age and clinical circumstances can affect suitability. Do not use an inverse result as a weight or height recommendation. A licensed clinician must determine any clinical application.
Unit Conversions Used for Du Bois BSA
| Conversion | Formula |
|---|---|
| Pounds to kilograms | lb × 0.45359237 |
| Meters to centimeters | m × 100 |
| Inches to centimeters | in × 2.54 |
| Feet to centimeters | ft × 30.48 |
| Square meters to square feet | m² ÷ 0.09290304 |
Example Calculations
Example 1: BSA using kilograms and centimeters
Suppose your weight is 70 kg and your height is 175 cm.
The result is approximately 1.8481 m².
Example 2: BSA using pounds and feet plus inches
Suppose your weight is 180 lb and your height is 5 ft 10 in.
The result is approximately 1.9959 m², or about 21.48 ft².
FAQ
What is Du Bois BSA?
Du Bois BSA is an estimate of body surface area calculated from height and weight. It is named after the Du Bois formula, which is commonly written as BSA = 0.007184 × weight0.425 × height0.725, using kilograms and centimeters.
Why does the formula use kg and cm?
The Du Bois formula was defined with weight in kilograms and height in centimeters. If you enter pounds, feet, inches, or meters, those values need to be converted first so the formula stays consistent.
Is Du Bois BSA the same as BMI?
No. BSA estimates the surface area of the body, usually in square meters. BMI estimates weight relative to height, usually in kg/m². They use different formulas and answer different questions.
