CalcBSA & Chemotherapy Dosing Calculator
Last updated: 2026-08-24
How to Use This Calculator
This calculator helps oncology professionals and patients determine body surface area (BSA) and convert chemotherapy dose from per-square-meter to actual milligrams. Start by entering the patient's height in centimeters and weight in kilograms. Then choose the BSA formula you want to use: Mosteller (recommended for adults) or Du Bois (an older formula often used in research). If you have a prescribed dose in mg/m², enter it in the optional field. Click 'Calculate' to get the BSA and the total dose for a single administration.
Formula and Methodology
Mosteller formula: BSA (m²) = √(height (cm) × weight (kg) / 3600). It is simple and widely accepted. Du Bois formula: BSA = 0.007184 × height (cm)^0.725 × weight (kg)^0.425. This formula was derived from a limited population and may slightly differ, especially for extremes of height and weight. For dosing, BSA is used to account for the patient's metabolic mass, aiming to provide a more personalized dose than weight-based dosing.
Practical Examples
Consider a patient with height 170 cm and weight 70 kg. Using Mosteller: BSA = √(170×70/3600) = √3.3056 ≈ 1.82 m². If the prescribed dose is 100 mg/m², total dose = 1.82 × 100 = 182 mg. Using Du Bois: BSA = 0.007184 × 170^0.725 × 70^0.425 ≈ 1.85 m² (slightly different). Total dose would be 185 mg. This difference may matter for highly toxic drugs, so accuracy is critical.
Tips and Best Practices
Always use the exact height and weight taken on the same day. Use a calibrated scale and stadiometer. For obese patients, some protocols use adjusted body weight for dosing; consult guidelines. Double-check all calculations with a second professional or pharmacist. Round BSA to two decimal places and dose to one decimal place as per institutional policy. Be aware of drug-specific dose adjustments for organ dysfunction. This calculator is for educational purposes; clinical decisions must be made by qualified healthcare providers.
FAQ
Which BSA formula is most commonly used for chemotherapy dosing?
Mosteller's formula is widely used due to its simplicity, but some institutions prefer Du Bois as it was derived from a more diverse patient population. The choice depends on institutional protocol and clinical judgment. Always consult your oncology pharmacist for the specific protocol.
How do I convert a dose in mg/m² to mg?
Multiply the dose in mg/m² by the patient's computed BSA. For example, if a dose is 100 mg/m² and the patient's BSA is 1.8 m², the total dose is 180 mg. This calculator does that conversion automatically.