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Online Medical Tools — BSA Calculator

Printed on 2/13/2026

For informational purposes only. This is not medical advice.


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BSA Calculator

Body surface area (BSA) estimates the total surface area of the human body. It is a more accurate indicator of metabolic mass than body weight alone and is widely used in medicine to calculate drug dosages (especially chemotherapy), determine cardiac index, and assess burn severity. Several formulas have been developed, each with slightly different estimates.

Formula: Du Bois: BSA = 0.007184 × height^0.725 × weight^0.425

Disclaimer: This tool is for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.

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Frequently Asked Questions

What is body surface area used for?

BSA is primarily used in medicine to calculate drug dosages (especially chemotherapy agents), determine cardiac index, assess kidney function, and estimate burn injury extent. It provides a more physiologically relevant measure than weight alone because it better correlates with metabolic rate.

Which BSA formula is most commonly used?

The Du Bois formula (1916) is the most widely used in clinical practice, though the Mosteller formula is popular for quick bedside calculations due to its simplicity. The Haycock formula is often preferred for pediatric patients.

What is a normal BSA for adults?

Average BSA is approximately 1.7 m² for adult women and 1.9 m² for adult men. However, BSA varies widely depending on height and weight. Most adults fall between 1.5 and 2.2 m².

Why is BSA used instead of weight for drug dosing?

BSA correlates better with cardiac output, blood volume, and metabolic rate than body weight alone. This makes BSA-based dosing more accurate, especially for drugs with narrow therapeutic windows like chemotherapy agents, where small dosing errors can have serious consequences.