Body Surface Area Calculator
Calculate body surface area (BSA) in m² from height and weight using the Mosteller, Du Bois, Haycock and Gehan & George formulas side by side, in metric or imperial units.
Input
In centimeters or inches, per the Units selection above.
In kilograms or pounds, per the Units selection above.
Output
| Formula | BSA |
|---|---|
| No data yet | |
Reference calculation, not medical advice. Clinical dosing decisions should be made by a qualified professional using institutional protocols.
More ways to use this tool
REST API
curl -X POST https://api.iotools.cloud/v1/tool/body-surface-area-calculator \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"units": "metric",
"height": "175",
"weight": "70"
}'Swap in your own key from your account. The tool's fields are the body — no wrapper.
Ask an AI agent
Use the IOTools `body-surface-area-calculator` tool (Body Surface Area Calculator) on this input:
YOUR_INPUT_HEREPaste this at any agent connected to the IOTools MCP server, then add your input.
Embed widget
<iframe
src="https://iotools.cloud/embed/body-surface-area-calculator/"
width="100%" height="520" frameborder="0" scrolling="no" loading="lazy"
title="Body Surface Area Calculator — iotools.cloud"
sandbox="allow-scripts allow-forms allow-same-origin allow-downloads allow-popups allow-popups-to-escape-sandbox"
allow="clipboard-write"
style="width:100%;border:1px solid #e5e7eb;border-radius:12px;overflow:hidden"></iframe>
<script src="https://iotools.cloud/embed.js" async></script>Drop this into your own page — free, no key required, just a link back.
| Cost per API/MCP call | From 5 credits |
|---|---|
| Need more credits? | View pricing |
Also available with
Guides
Body surface area (BSA) is the total external area of the body in square metres. Clinicians use it instead of raw weight to scale chemotherapy doses, cardiac index, glomerular filtration rate and burn assessments, because it tracks metabolic mass better than weight alone.
Several formulas are in published use and they disagree by a few hundredths of a m². This calculator runs four at once so you can see the spread.
How to use it
- Choose Units — metric (cm / kg) or imperial (in / lb).
- Enter your Height and Weight.
- Read the BSA from each formula, plus their average.
The formulas
| Formula | Equation (cm, kg) |
|---|---|
| Mosteller (1987) | √(height × weight ÷ 3600) |
| Du Bois (1916) | 0.007184 × weight^0.425 × height^0.725 |
| Haycock (1978) | 0.024265 × weight^0.5378 × height^0.3964 |
| Gehan & George (1970) | 0.0235 × weight^0.51456 × height^0.42246 |
Mosteller is the most widely quoted because it is easy to compute by hand. Haycock and Gehan & George were fitted with children in the sample, so they are often preferred for paediatric work. An average adult has a BSA of roughly 1.7–1.9 m².
Everything is calculated in your browser; nothing is uploaded. This is a reference calculation, not medical advice.