BSA Calculator – Body Surface Area
Calculate body surface area using provided height and weight across several established formulas. BSA Calculator – Body Surface Area helps clinicians, pharmacists, and patients estimate dosing-related body measurements.
Highlights
- Estimate body surface area using height and weight.
- Compare results from five established clinical formulas.
- Includes Mosteller, Du Bois, Haycock, Gehan–George, and Boyd methods.
- Supports metric and imperial height and weight units.
- View results in square meters or square feet.
Table of Contents
How BSA Calculator – Body Surface Area Works?
The BSA Calculator estimates body surface area from standing height and body weight. It applies several established clinical formulas so users can compare the Mosteller, Du Bois, Haycock, Gehan–George, and Boyd estimates. The calculator accepts height in cm, m, in, or ft and weight in kg, g, lb, or st, then reports the results in m² or ft².
The primary result uses the Mosteller formula because it is simple and widely used in clinical practice:
When height is expressed in centimeters and weight in kilograms, this formula produces an estimate in square meters. The other methods use empirically derived power relationships:
| Method | Formula | Typical purpose |
|---|---|---|
| Mosteller | BSA = √(height × weight ÷ 3600) | Common general clinical estimate |
| Du Bois | BSA = 0.007184 × height0.725 × weight0.425 | Classic reference method |
| Haycock | BSA = 0.024265 × height0.3964 × weight0.5378 | Useful across pediatric and adult populations |
| Gehan–George | BSA = 0.0235 × height0.42246 × weight0.51456 | Additional clinical comparison |
| Boyd | BSA = 0.0003207 × height0.7285 × weight0.3 | Additional established reference |
For example, a person entered with a height of 170 cm and a weight of 70 kg receives five separate estimates. Since the equations were developed from different study populations, small differences between methods are expected. The results are estimates of total body surface area, not a direct measurement of skin surface.
Practical Use Cases
Clinicians can use the BSA estimates as a supplementary body-size measurement when reviewing medication protocols, assessing clinical status, or documenting a patient's physical measurements. The Mosteller result is often a convenient reference, while the other formulas provide useful comparisons.
Pharmacists can use BSA estimates when checking therapies whose prescribing information or institutional protocol specifies dosing by body surface area. The calculated value should always be reviewed alongside the approved drug labeling, treatment protocol, and patient-specific clinical factors.
Pediatric healthcare professionals can compare the Haycock and other formula results when assessing children or adolescents, for whom height and weight can change rapidly. Current, accurately measured inputs are especially important for repeat calculations.
Patients and caregivers can use the calculator to understand a BSA value shown in medical records or discussed during treatment planning. It should support conversations with a qualified healthcare professional rather than be used to independently change a medication dose.
Researchers and students can compare how the Mosteller, Du Bois, Haycock, Gehan–George, and Boyd equations respond to the same height and weight inputs, making the calculator useful for studying clinical measurement methods.
Accuracy and Limitations
The calculator produces formula-based estimates, and the five methods may return slightly different values because each was derived from a different population and mathematical model. Accuracy depends strongly on entering current, reliable height and weight measurements within the supported input ranges of 1–300 for height and 0.1–1000 for weight. BSA formulas do not directly account for body composition, edema, unusual body proportions, pregnancy, amputation, or major fluid changes, so the result may be less representative in these situations. A BSA estimate must not be used by itself to determine or change a medication dose; clinical protocols, prescribing information, and professional judgment remain necessary.
Quick Examples
Example #1: Average Adult
Estimate body surface area for an average adult using height in centimeters and weight in kilograms.
Example #2: Tall Adult in Imperial Units
Calculate body surface area for a tall adult using height in feet and weight in pounds.
Example #3: Pediatric Measurement
Estimate body surface area for a child using height in centimeters and weight in grams.
