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Body Surface Area Calculator

BSA by the Du Bois, Mosteller, Haycock and Boyd formulas.

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Every formula

Each was fitted to a different population, so a two to five percent disagreement is normal.

FormulaBSA (m²)vs MostellerIndexed value

The equations

  • Mosteller: √(height × weight ÷ 3600)
  • Du Bois: 0.007184 × height0.725 × weight0.425
  • Haycock: 0.024265 × height0.3964 × weight0.5378
  • Gehan-George: 0.0235 × height0.42246 × weight0.51456
  • Boyd: uses a weight-dependent exponent, and reads highest at low weights.

Body surface area (Mosteller)

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Summary

Lowest formula—
Highest formula—
Spread—
Relative to 1.73 m²—

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Total from the dose per m² you entered

An educational calculator. Mosteller is the usual bedside choice because its square-root form can be done mentally; Du Bois is the historical reference. Typical adult values run about 1.6 to 1.9 m², and 1.73 m² is the standard used for indexing kidney function. Any real dose must come from a clinical protocol.

Quick Tool Overview

The Body Surface Area Calculator computes BSA in square metres from height and weight using five published formulas — Du Bois, Mosteller, Haycock, Gehan-George and Boyd — shown together, because they differ by a few percent and clinical protocols specify which to use.

What it does
Calculates body surface area by five formulas
You give it
Height and weight in metric or imperial units
You get back
Five BSA values in m² and the spread between them
Best for
Dose calculations, cardiac index and clinical education
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About the Body Surface Area Calculator

Calculate body surface area in square metres from height and weight. Five published formulas are computed together — Du Bois, Mosteller, Haycock, Gehan-George and Boyd — because they routinely disagree by a few percent and clinical protocols specify which to use.

Body surface area is used in medicine wherever dose should scale with metabolic size rather than with weight: chemotherapy dosing, cardiac index, burn assessment and paediatric fluid calculations all key off it. Mosteller is the one most often used at the bedside, simply because its square-root form can be done in your head, while Du Bois remains the historical reference the others are validated against. This is an educational calculator, not a prescribing tool.

Key features of the Body Surface Area Calculator

Five formulas side by side

Du Bois, Mosteller, Haycock, Gehan-George and Boyd, with the percentage spread between highest and lowest.

Mosteller highlighted

The bedside default is called out, since its square-root form is the one clinicians can do mentally.

Reference values given

The typical adult range and the 1.73 m² standard used for indexing kidney function are shown for context.

Explains the disagreement

Each formula was fitted to a different population, which is why a two to five percent difference is normal.

Educational, not prescribing

The page is explicit that a dose should come from a protocol, not from a web calculator.

How to use the Body Surface Area Calculator

  1. 1

    Enter height and weight

    In metric or imperial units — conversion is handled for you.

  2. 2

    Compare the formulas

    All five results are shown together with the spread between the highest and lowest.

  3. 3

    Pick the required formula

    Use whichever your protocol specifies; the differences are small but not always negligible.

  4. 4

    Read the derived values

    The BSA-indexed figure and the percentage spread between formulas are shown beneath the result.

Frequently asked questions

Chemotherapy dosing, cardiac index, burn extent and paediatric fluid and drug calculations, wherever scaling by metabolic size is more appropriate than scaling by weight.

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