Simple tools for everyday life.

Body Surface Area (BSA) Calculator

Calculate body surface area using the Du Bois, Mosteller or Haycock formulas.

Tip: For children, the Haycock formula is the most accurate since it was validated specifically for paediatric age. For obese adults, use Mosteller.

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About this digital tool

The body surface area (BSA) calculator works out the skin surface in square metres from height and weight. You can choose between three formulas: Du Bois, Mosteller or Haycock, and see the result to two decimal places.

The formulas used: Du Bois 0.007184 × height^0.725 × weight^0.425; Mosteller √(height × weight ÷ 3600); Haycock 0.024265 × height^0.3964 × weight^0.5378 (height in cm, weight in kg). BSA is used in medicine to normalise values such as heart function, kidney function or the doses of some drugs. This calculator is for information only: drug dosing is always determined by the doctor or pharmacist and shouldn't be based on an online tool.

How to use

  1. Enter your weight (kg)
  2. Enter your height (cm)
  3. Choose the formula (Du Bois, Mosteller, Haycock)
  4. See the BSA in m²
  5. Compare with average values for age/gender

Frequently asked questions

Why is BSA used in medicine?

BSA correlates better than weight with metabolic functions (kidney filtration, cardiac output). Many drugs, especially chemotherapy, are dosed in mg/m² to ensure an effective dose without toxicity.

Which formula should I use?

Du Bois: the standard for adults. Mosteller: simpler, accurate. Haycock: best for children. Boyd: takes age into account. The average of Du Bois and Mosteller gives the most reliable result.

What is the average BSA?

Men: 1.7–2.0 m². Women: 1.5–1.8 m². A 10-year-old child: ~1.1 m². Infant: ~0.25 m². Values above 2.2 m² are considered high.

Which BSA formula is the most used?

Mosteller is simple and widely used in practice; Du Bois is the classic. Haycock is often preferred for children. The results differ slightly.

Can I use BSA to calculate a drug dose?

No. Doses are determined by the doctor or pharmacist. This calculator is for information only.