Body Surface Area Calculator
Body Surface Area (BSA) Calculator works out Body surface area and Equation used from Equation for the headline figure, Height and Height unit. The default figures on this page give body surface area of 1.8447 m^2; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
4 steps
- Height 175 cm, weight 70 kg.
- Mosteller: sqrt(175 x 70 / 3600) = sqrt(3.402778) = 1.8447 m^2.
- The four published equations span 0.0092 m^2, or 0.5% of the headline figure.
- Indexed to the standard 1.73 m^2 this is a ratio of 1.0663.
All equationstable
| formula | bsa | differenceFromChosen | citation |
|---|---|---|---|
| Mosteller (1987) | 1.8447 | 0 | Mosteller RD. Simplified calculation of body-surface area. N Engl J Med 1987;317:1098. |
| Du Bois & Du Bois (1916) | 1.8481 | 0.0035 | Du Bois D, Du Bois EF. A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med 1916;17:863-871. |
| Haycock (1978) | 1.8468 | 0.0021 | Haycock GB, Schwartz GJ, Wisotsky DH. Geometric method for measuring body surface area. J Pediatr 1978;93:62-66. |
| Gehan & George (1970) | 1.8539 | 0.0092 | Gehan EA, George SL. Estimation of human body surface area from height and weight. Cancer Chemother Rep 1970;54:225-235. |
Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
5 sources
What the Body Surface Area (BSA) Calculator calculates
Estimates body surface area in m² from height and weight by the Mosteller, Du Bois, Haycock and Gehan-George equations, showing all four side by side with the spread between them and the ratio to the standard 1.73 m².
How to use this Body Surface Area (BSA) Calculator
Enter Equation for the headline figure, Height, Height unit and Weight. Body surface area updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Body surface area, Equation used and Mosteller.
The method follows Mosteller RD. Simplified calculation of body-surface area, Du Bois D, Du Bois EF. A formula to estimate the approximate surface area if height and weight be known, Haycock GB, Schwartz GJ, Wisotsky DH. Geometric method for measuring body surface area: a height-weight formula validated in infants, children and adults, Gehan EA, George SL. Estimation of human body surface area from height and weight and KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease.
Mosteller for 175 cm and 70 kg example
With Equation for the headline figure: mosteller, Height: 175, Height unit: cm, Weight: 70, the calculator returns Body surface area: 1.84466197. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Body surface area, Equation used and Mosteller. The inputs you can vary are Equation for the headline figure, Height, Height unit, Weight and Weight unit.
Understanding Body surface area, Equation used and Mosteller
An estimate from published regression equations, not a measurement. Different equations give different answers for the same person; when BSA is used to dose a drug, use the equation the protocol specifies, and leave the dose itself to the prescriber.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How do I calculate my body surface area?
Estimates body surface area in m² from height and weight by the Mosteller, Du Bois, Haycock and Gehan-George equations, showing all four side by side with the spread between them and the ratio to the standard 1.73 m². Open “How this is worked out” beside the result to see each step for your own figures.
How do I calculate my BSA?
It needs Equation for the headline figure, Height, Height unit, Weight and Weight unit. Nothing else is required, and the figures stay in your browser.
What is the normal BSA by age?
On the figures this page opens with — height 175 and weight 70 — the body surface area is 1.8447 m². No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
What information do I need for the Body Surface Area (BSA) Calculator?
You need Equation for the headline figure, Height, Height unit, Weight and Weight unit. The page opens with default figures that give body surface area of 1.8447 m^2, so you can see the scale before entering your own.
What does this Body Surface Area (BSA) Calculator show?
It shows Body surface area, Equation used, Mosteller, Du Bois, Haycock, Gehan & George, Spread across the four equations and Spread as a share of the headline figure, with the working and any warnings for your entries.
Can I check how the Body Surface Area (BSA) Calculator result was calculated?
Yes. The “How this is worked out” section shows the calculation steps, and the sources section identifies the references used for the method.