Transparent method
The formula
Worked example
Example inputs
How to interpret the result
Two established formulas, Mosteller and Du Bois, estimate body surface area slightly differently, and the gap between them, while usually small, is exactly why clinical dosing protocols specify which formula to use rather than accepting either interchangeably. Consistency of method matters as much as the number itself in that context.
Before you rely on it
What to check
Confirm which formula a clinical protocol specifies before using its output for anything beyond a general reference, and never substitute this tool's result for a clinician's own calculation in an actual dosing decision.
The common error
Where people go wrong with body surface area calculator
Treating either formula's output as automatically interchangeable with the other, or as a substitute for a clinical team's own BSA calculation. The small formula differences are exactly why medical protocols name a specific one rather than leaving the choice open.
Sensitivity evidence
How weight changes the body surface area (mosteller)
| Weight | Body surface area (Mosteller) | Body surface area (Du Bois, cross-check) |
|---|---|---|
| 136 | 1.7 | 1.8 |
| 153 | 1.8 | 1.8 |
| 170worked example | 1.9 | 1.9 |
| 187 | 2 | 2 |
| 204 | 2.1 | 2.1 |
Every input, tested
Which input moves the body surface area (mosteller) most
| Input | Tested from | To | Body surface area (Mosteller) at each end | Swing |
|---|---|---|---|---|
| Height | 62 | 76 | 1.8 to 2 | 0.197 (10%) |
| Weight | 153 | 187 | 1.8 to 2 | 0.194 (10%) |
Two variables at once
Body surface area (Mosteller) by weight and height
| Weight \ Height | 55 | 69 | 83 |
|---|---|---|---|
| 136 | 1.5 | 1.7 | 1.9 |
| 153 | 1.6 | 1.8 | 2 |
| 170 | 1.7 | 1.9 | 2.1 |
| 187 | 1.8 | 2 | 2.2 |
| 204 | 1.9 | 2.1 | 2.3 |
Step by step
The worked example, input by input
| Input | Value used | What it means |
|---|---|---|
| Weight | 170 | Body weight in pounds. |
| Height | 69 | Height in inches. |
| Body surface area (Mosteller) | 1.9 | |
| Body surface area (Du Bois, cross-check) | 1.9 | |
Inputs, definitions and assumptions
Weight
Body weight in pounds.
Height
Height in inches.
Where the inputs come from
Enter your weight and height in the units offered. The Mosteller formula takes the square root of height in centimeters times weight in kilograms divided by 3,600, and the Du Bois formula is an older cross-check. The tool converts pounds and inches for you. Measure recently, since chemotherapy and other clinical doses depend on current body size. This tool is informational and does not replace the calculation your care team performs.
When the result stops applying
Doses for a patient are calculated by the treating team using their own protocols and may cap the value. Never use this to set or change a medication dose.
What to compare it with
See the BMI calculator, and the creatinine clearance calculator that clinicians use to adjust drug doses for kidney function. The healthy weight and lean body mass pages help interpret body size. Ask your pharmacist or clinician how your own doses are calculated.
People also ask
Frequently asked questions
What is body surface area used for?
Clinicians use it to calculate doses for some medicines, especially chemotherapy, and to assess burns and cardiac output relative to body size.
Which formula is better, Mosteller or Du Bois?
Both give nearly the same value for typical adults. Mosteller is simpler and widely used, and the results differ by about 0.01 to 0.05 square meters.
Can I use this to calculate a medicine dose?
No. Doses are set by prescribers using protocols that may adjust or cap the figure, so use this only for information.