Body Surface Area Calculator
Estimate body surface area (BSA) from height and weight using the Mosteller, Du Bois, Haycock, Gehan-George, and Boyd formulas, in metric or imperial. Calculates in your browser.
Body surface area (Mosteller)
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Show the math
The Mosteller formula is the simplest and most widely used:
BSA = √(height × weight ÷ 3600)
The Du Bois, Haycock, Gehan-George, and Boyd formulas use fitted power laws of height and weight. They were each derived from a different study group, so they disagree by a few percent, treat the spread as a band, and use the Mosteller value unless a specific formula is prescribed for you.
What this does
A body surface area (BSA) calculator estimates the total area of your skin in square metres from your height and weight. BSA is widely used in medicine — for example, to scale drug doses and cardiac output — because it tracks body size better than weight alone.
How to use it
- Enter your height and weight.
- Switch between metric and imperial if needed.
- Read the BSA from each formula.
- Use the Mosteller value unless a formula is specified for you.
How it works
The Mosteller formula takes the square root of height (cm) times weight (kg) divided by 3600. The Du Bois, Haycock, Gehan-George, and Boyd formulas use fitted power laws of height and weight and usually agree within a few percent.
BSA = √(height×weight / 3600)
Understanding your result
A typical adult BSA is roughly 1.5–2.0 m². The formulas differ slightly because each was fitted to a different study group; the Mosteller formula is the most common in clinical practice because it is simple and accurate.
Example
At 180 cm and 75 kg, the Mosteller BSA is about 1.94 m².
Sources & methodology
Last updated .
Frequently asked questions
Which BSA formula should I use?
Mosteller is the most widely used because it is simple and accurate. Du Bois is the historical standard. Unless your clinician specifies one, the values are close enough to be interchangeable.
What is a normal body surface area?
Most adults fall between about 1.5 and 2.0 m², with larger people higher. Children are much lower, which is why BSA is used for paediatric dosing.
Is my data stored?
No. Everything is calculated locally in your browser.
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