Body Surface Area (BSA) Calculator
| Formula | BSA (m²) |
|---|---|
| Du Bois (1916) | — |
| Mosteller (1987) | — |
| Haycock (1978) | — |
| Boyd (1935) | — |
Average BSA (across formulas)
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Interpretation
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Understanding Body Surface Area and Its Medical Applications
Body Surface Area (BSA) is a clinical measurement that estimates the total area of the human body's outer surface, expressed in square meters. Unlike body weight alone, BSA accounts for both height and weight, providing a more proportional indicator of body size. The average adult BSA is approximately 1.7 m² for women and 1.9 m² for men, though this varies significantly with body composition.
BSA is critically important in medicine, particularly for calculating chemotherapy drug dosages, where precise dosing can mean the difference between effective treatment and dangerous toxicity. It is also used to compute the cardiac index (cardiac output divided by BSA), estimate glomerular filtration rate for kidney function assessment, and determine appropriate dosing for many other medications. Several formulas have been developed over the past century, each with different strengths.
The Du Bois formula (1916) is the historical standard, validated against direct surface measurements. The Mosteller formula (1987) is favored for its mathematical simplicity and is widely used in clinical practice. The Haycock formula (1978) is particularly well-suited for pediatric patients, as it was developed using measurements from children and infants. The Boyd formula (1935) places greater emphasis on weight and may provide different results for obese patients. This calculator presents all four formulas simultaneously so you can compare results.
Frequently Asked Questions
What is Body Surface Area (BSA)?
BSA is a measurement of the total surface area of the human body in square meters. The average adult BSA is about 1.7 m². It is used in medicine for drug dosing, cardiac index, and kidney function estimation.
What is the Du Bois formula?
The Du Bois formula (1916) is: BSA = 0.007184 x Height(cm)^0.725 x Weight(kg)^0.425. It is one of the most widely used BSA formulas in clinical practice.
Which BSA formula is most accurate?
No single formula is universally most accurate. Mosteller is popular for simplicity, Haycock is preferred for children, Du Bois is the historical standard, and Boyd emphasizes weight. Most agree closely for average adults.
Why is BSA used instead of body weight for drug dosing?
BSA correlates better with cardiac output, blood volume, renal function, and metabolic rate. Drug clearance scales more proportionally with BSA, which is critical for drugs with narrow therapeutic windows like chemotherapy agents.