BSA Calculator (Mosteller)
Body surface area for chemotherapy dosing, cardiac index, and pediatric maintenance fluid estimates.
Understanding this tool
Why nurses use it
Body surface area (BSA) indexes drug doses (especially chemotherapy) and haemodynamic values such as cardiac index. The Mosteller formula is widely used because it is simple and correlates well with direct measurement.
When to use it
Use when protocols reference m² — oncology, cardiac index, or some paediatric calculations. Chemotherapy must always be verified by oncology pharmacy.
Calculate
How to use this calculator
- Enter height and weight (converted to metric internally if needed).
- Use the BSA result only as referenced by the specific protocol.
- Verify chemotherapy and high-risk BSA dosing with pharmacy.
How the calculation works
Mosteller: BSA (m²) = √[(height cm × weight kg) ÷ 3600]. It approximates surface area from two easy bedside measurements.
Formula used by this tool — verify units before applying at the bedside.
Worked example
Limitations & clinical notes
- Multiple BSA formulas exist; institutions may prefer Du Bois or other equations.
- Chemotherapy dosing must follow protocol-specific BSA rules.
References
Key sources: Mosteller RD — Simplified calculation of body surface area.
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Disclaimer: This calculator is for educational and bedside double-check purposes only. It does not replace institutional protocols, prescriber orders, pharmacist verification, or clinical judgment. Always follow your local policies — especially for high-risk medications, infusions, pediatrics, and critical care. If the patient is acutely unwell, escalate immediately rather than relying on any calculator output.