BSA Calculator
Estimate body surface area (BSA) using Mosteller, Du Bois, Haycock, Gehan-George, and Boyd formulas. Compare outputs side by side.
Average BSA
1.849 m²
Formula range: 1.845 to 1.854 m²
| Formula | BSA (m²) |
|---|---|
| Mosteller | 1.845 |
| Du Bois | 1.848 |
| Haycock | 1.847 |
| Gehan-George | 1.854 |
| Boyd | 1.851 |
Formula spread map
If formula spread is large, compare with your clinic's preferred method for consistency.
What is BSA?
Body Surface Area (BSA) is an estimated total skin surface area, usually expressed in square meters (m²). It is commonly used in medical contexts because some physiological processes correlate better with surface area than with body weight alone.
BSA is widely used for chemotherapy dosing, burn assessment, renal function indexing, and cardiac output normalization. It is an estimate, not a direct measurement.
Why formulas differ
Different BSA formulas are derived from different populations and statistical methods. Mosteller is popular for simplicity, while Du Bois and others may vary slightly at body size extremes.
Mosteller
Fast mental calculation and common bedside use.
Du Bois / Haycock
Traditional references in research and pharmacology.
Boyd / Gehan-George
Alternative fits that can diverge in very low or high body mass.
Clinical context and cautions
BSA helps standardize dosing, but dosing decisions should still consider age, organ function, treatment intent, and clinical protocol.
For pediatrics, obesity, cachexia, or unusual body composition, formula differences can be clinically relevant. Use local guideline recommendations when available.
This calculator is for educational and planning purposes. It does not replace licensed medical judgment.
Formula selection guide by use case
| Formula | Typical use | Practical note |
|---|---|---|
| Mosteller | Bedside estimation | Simple and fast, often used in daily practice. |
| Du Bois | Legacy references | Common in older literature and protocols. |
| Haycock | Pediatric contexts | Sometimes preferred for smaller body sizes. |
| Boyd / Gehan-George | Sensitivity comparison | Useful for checking range in edge populations. |