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Body Surface Area (BSA) Calculator — Free Online Calculator

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Body Surface Area

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About This Calculator

Body Surface Area (BSA) is used in medicine for drug dosing (especially chemotherapy), renal clearance normalization, burn assessment, and cardiac index calculation. The Du Bois formula (1916) is the most widely used, while the Mosteller formula offers a simpler calculation. Average adult BSA is approximately 1.7 m² for females and 1.9 m² for males.

Formula

Du Bois: BSA (m²) = 0.007184 × Height (cm)^0.725 × Weight (kg)^0.425
Mosteller: BSA (m²) = √(Height (cm) × Weight (kg) / 3600)

Interpretation

BSA (m²)Interpretation
< 1.5Below average adult
1.5 – 2.2Normal adult range
> 2.2Above average adult

References

  1. 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.
  2. Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987;317(17):1098.

Frequently Asked Questions

Why is BSA used for chemotherapy dosing?

BSA is used because it correlates better with drug clearance and organ size than body weight alone. Most chemotherapy regimens specify doses in mg/m². However, BSA-based dosing has limitations, and some newer drugs use fixed dosing or pharmacokinetic-guided dosing instead.

Which BSA formula should I use?

The Du Bois formula is the most widely used and cited. The Mosteller formula is simpler and gives very similar results. For most clinical purposes, either formula is acceptable. The choice may depend on institutional protocol.

Should BSA be capped for obese patients?

This is debated. Some institutions cap BSA at 2.0 m² for chemotherapy dosing in obese patients, but ASCO guidelines recommend using actual body weight without capping, as dose reductions in obesity may compromise treatment efficacy. The decision should be individualized.

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⚠ Medical Disclaimer

This tool is for educational and informational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional for clinical decisions.