Which BSA formula should I use?

Du Bois & Du Bois (1916) is the historical standard. Mosteller (1987) is the simplest and most widely used clinically. Haycock (1978) works well across children and adults. This tool lets you switch between all three.

What is the Mosteller formula?

BSA (m²) = √(height in cm × weight in kg ÷ 3600). It is popular because it is easy to compute by hand and agrees closely with the older Du Bois formula.

What is body surface area used for?

BSA scales many clinical values to body size — most commonly chemotherapy and other drug doses, cardiac index, and burn assessment. It often tracks physiology better than weight alone.

Why do the three formulas give slightly different results?

Each was fitted to different reference data with different exponents, so they diverge a little, especially at the extremes of height and weight. The differences are usually small for typical adults.

Does it work in imperial units?

Yes. Feet, inches and pounds are converted to centimetres and kilograms before the formulas are applied, so the BSA is always returned in square metres.

Is this a substitute for clinical judgement?

No. It is a calculation aid. Dosing and clinical decisions must be made by a qualified professional using the appropriate reference for the patient.

Is my data sent anywhere?

No. Every calculation runs locally in your browser and nothing is uploaded.

Body Surface Area Calculator

Body surface area (BSA) calculator

Body surface area estimates the total external area of the body in square metres. It is widely used in medicine to scale drug doses (notably chemotherapy), cardiac index and other values to body size, because it often reflects physiology better than weight alone.

How it works

All three formulas take height in centimetres and weight in kilograms (imperial inputs are converted first) and return BSA in m²:

Du Bois: 0.007184 × height^0.725 × weight^0.425 Mosteller: √(height × weight ÷ 3600) Haycock: 0.024265 × height^0.3964 × weight^0.5378

The tool computes the selected formula live and lets you switch between them to compare.

Example

Height 178 cm, weight 75 kg:

Formula	BSA
Du Bois	≈ 1.93 m²
Mosteller	≈ 1.93 m²
Haycock	≈ 1.93 m²

(Computed as Mosteller = √(178 × 75 ÷ 3600) = √3.708 ≈ 1.93 m².) The three agree closely for a typical adult. Everything runs in your browser, with nothing uploaded.