Rituximab Dose Calculator

Calculator Inputs

Example Data Table

Formula Used

• Body surface area (Mosteller): BSA (m²) = √((Height(cm) × Weight(kg)) / 3600)
• mg/m² dosing: Dose per infusion (mg) = (mg/m²) × BSA
• Fixed dosing: Dose per infusion (mg) = ordered fixed amount
• Volume estimate: Volume (mL) = Dose (mg) ÷ 10 (mg/mL)
• Vial planning: Chooses 500 mg and 100 mg vials to meet or exceed the dose with minimal waste.

How to Use This Calculator

1. Select a regimen preset that matches your protocol.
2. Enter patient weight and height to calculate BSA automatically.
3. If you already have BSA, switch to manual BSA and enter it.
4. Use custom dosing only when you have an explicit order.
5. Choose a rounding increment appropriate for your setting.
6. Press Calculate Dose to show results above the form.
7. Use the CSV/PDF buttons to export the latest calculation.

Why dose estimation matters in practice

Rituximab orders are commonly expressed as either mg/m² (surface area–based) or fixed milligrams per infusion. Converting the order into a practical preparation plan requires consistent body size inputs, clear rounding rules, and a repeatable way to translate milligrams into vial quantities and volume estimates. For mg/m² regimens, small entry errors in height or weight can shift the final dose by margins, so a readable summary helps support a double-check.

Body size inputs and BSA standardization

This calculator uses the Mosteller method to estimate body surface area from height and weight. Standardizing BSA selection reduces variation across staff and keeps calculations transparent. When a verified BSA is documented, manual entry preserves that value for reconciliation and review. The inputs are in centimeters and kilograms to reduce unit mismatch, and the result is shown to two decimals for quick cross-checking against charted values.

Regimen presets and indication-aware workflows

Preset regimens support common adult patterns such as 375 mg/m² protocols and 1000 mg fixed schedules. Selecting a preset also carries a schedule note into the output, helping teams communicate timing and dose count. The dose-count field estimates total course exposure (mg), which is useful for planning infusion chair time and documenting cumulative therapy. Custom mode remains available for local pathways, protocol-specific modifications, and clinician-directed adjustments.

Rounding choices and audit-friendly outputs

Rounding is a workflow choice and should follow local policy. The calculator can round to practical increments (1 to 100 mg) so teams can standardize communication. Rounding also affects vial selection and estimated waste, so documenting the increment improves repeatability between shifts. The displayed dose is the rounded planning target, while the underlying mg/m² math is still visible for traceability during verification.

Vial planning with waste awareness

To support preparation planning, the tool estimates the number of 500 mg and 100 mg vials needed to meet or exceed the target dose while minimizing leftover drug. It reports supplied milligrams, estimated waste, and an implied volume at 10 mg/mL, enabling quick comparison when inventory constraints exist. The selection logic prioritizes minimal waste, then fewer vials, which can reduce compounding steps. Results assume single-patient vial use; where sharing is permitted, real waste may be lower.

FAQs

1) Is this calculator suitable for prescribing?

No. It is an educational estimator for planning and documentation. Always confirm indication, protocol, dose adjustments, and infusion parameters using approved references and institutional policy before preparing or administering any dose.

2) Which BSA formula is used?

The Mosteller formula is used: BSA = √((height in cm × weight in kg) ÷ 3600). If your workflow uses another method, enter a verified BSA manually for consistency.

3) Why does the vial plan sometimes exceed the target dose?

Vials come in fixed sizes. The calculator chooses 500 mg and 100 mg vials that meet or exceed the target with minimal waste. Partial-vial use, vial sharing, or compounding practices can change real-world waste.

4) Does the volume output equal the final infusion volume?

No. The volume is the drug solution volume at 10 mg/mL. Final infusion volume depends on dilution, compatible fluids, bag size, and preparation standards. Use the value as a planning reference.

5) How should I choose a rounding increment?

Choose the increment that matches local policy and compounding workflow. Smaller increments keep doses closer to the calculated value but may complicate preparation. Larger increments simplify planning but can shift total milligrams.

6) What do the CSV and PDF exports include?

Exports include regimen label, schedule note, patient inputs, calculated BSA, dose per infusion, course total, estimated drug volume, vial counts, supplied milligrams, and estimated waste. They reflect the most recent successful calculation.