Body Surface Area Calculator
Calculate your Body Surface Area (BSA) using Du Bois, Mosteller, or Haycock formulas.
What Is Body Surface Area Used For?
Body Surface Area (BSA) estimates the total area of skin covering your body. It sounds like a trivial measurement, but it's critical in medicine — far more than you'd expect.
Oncologists use BSA to calculate chemotherapy drug dosages. The more surface area you have, the more drug you need. Getting this wrong by even 10% can mean the difference between an effective dose and a toxic one. BSA is also used for cardiac index calculations (how efficiently your heart pumps relative to your body size), burn assessment, and kidney function analysis.
For the average person, BSA isn't something you need to track like BMI or body fat. But if you're curious about how your body compares to population averages, or if a medical professional has mentioned your BSA, this calculator gives you the number in seconds.
The Three BSA Formulas
| Formula | Year | Equation | Best For |
|---|---|---|---|
| Du Bois | 1916 | 0.007184 x H0.725 x W0.425 | Most widely used in clinical practice |
| Mosteller | 1987 | √(H x W / 3600) | Simplest calculation, very similar results |
| Haycock | 1978 | 0.024265 x H0.3964 x W0.5378 | More accurate for children and infants |
What this means for you: For adults, all three formulas give results within 2–3% of each other. Du Bois is the clinical standard, Mosteller is the simplest to calculate by hand, and Haycock is preferred for paediatric use. H = height in cm, W = weight in kg.
Average BSA by Sex and Height
| Height | Average Male BSA | Average Female BSA |
|---|---|---|
| 160 cm / 5'3" | 1.72 m² | 1.60 m² |
| 170 cm / 5'7" | 1.85 m² | 1.71 m² |
| 175 cm / 5'9" | 1.91 m² | 1.76 m² |
| 180 cm / 5'11" | 1.98 m² | 1.82 m² |
| 190 cm / 6'3" | 2.11 m² | 1.94 m² |
Values assume average weight for each height. The global average adult BSA is approximately 1.7 m² for women and 1.9 m² for men.
Medical Applications of BSA
Chemotherapy Dosing
Most chemotherapy drugs are dosed in mg/m² of BSA. This ensures that larger patients receive proportionally more drug, reducing under-dosing in large patients and toxicity in small patients.
Cardiac Index
Cardiac output (litres/min) divided by BSA gives the cardiac index — a normalised measure of heart function. Normal is 2.5–4.0 L/min/m². This allows comparison of heart performance across different body sizes.
Burn Assessment
The "Rule of Nines" estimates burn area as a percentage of BSA. Head = 9%, each arm = 9%, each leg = 18%, front torso = 18%, back = 18%. Fluid replacement in burn patients is calculated using BSA percentage.
Kidney Function (GFR)
Glomerular filtration rate (GFR) is normalised to a standard BSA of 1.73 m². This allows meaningful comparison of kidney function between individuals of different sizes.
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How to use this tool
Enter your weight in kilograms
Enter your height in centimetres
Select your preferred formula (Du Bois, Mosteller, or Haycock)
Common uses
- Calculating medication dosages in oncology
- Assessing cardiac output and cardiac index
- Estimating burn surface area for treatment
- Adjusting drug doses for body size
- Renal function assessment
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