Body Surface Area Calculator – Calculate BSA Online
Compute your body surface area with the Mosteller formula.
About the Body Surface Area Calculator
What is the Body Surface Area Calculator?
A body surface area calculator estimates the total surface of your skin in square metres using the Mosteller formula.
Why use this calculator?
BSA is used in medicine for fluid resuscitation, medication dosing and evaluating burns, where surface area matters more than weight alone.
How to use it
- Enter your height in centimetres and weight in kilograms.
- Read your BSA in square metres.
Formula
BSA = √(height × weight ÷ 3600).
Body surface area estimates are population averaged; individual variations exist.
Frequently Asked Questions
Why not just use weight?
Some drugs distribute across body surface rather than body mass, so BSA-based dosing can be safer and more effective.
Which formula do hospitals use?
Mosteller is common because it is simple. DuBois and Haycock are alternatives used in some settings.
Is this a medical diagnosis?
No. This tool provides general wellness information only. It is not a substitute for evaluation by a qualified healthcare professional.
Why do results differ from my doctor's measurements?
Clinical measurements use calibrated equipment and professional technique. Home estimates rely on formulas and self-reported values, so small differences are normal.
How often should I recalculate?
Recheck after meaningful changes such as weight gain or loss, a new workout routine, or every few months to track trends over time.
Do these formulas apply to everyone?
Most population formulas are less accurate for athletes, pregnant people, very young children and the elderly. Use them as a general guide.
Is this calculator free to use?
Yes. Every calculator on this site is completely free, with no hidden fees, no subscriptions and no limits on how many times you can use it.
How accurate are the results?
We use standard, widely accepted formulas and calculate in your browser using double-precision arithmetic. Results are rounded for readability, so treat them as reliable estimates rather than a guarantee. Real-world factors can vary the true figure.
Can I add this calculator to my own website?
Yes. Open this calculator page and use the "Add to your website" box in the sidebar to copy a ready-made iframe snippet, then paste it into any HTML page.
Does it work on a phone or tablet?
Yes. The layout is fully responsive, so it works on desktops, laptops, tablets and mobile phones, and every input adapts to touch screens.