Billing-unit calculator

Convert an administered dose to HCPCS billing units and see the arithmetic: rounding, vial utilization, and the quantity left over from single-dose containers.

1 · HCPCS billing unit

J0180 — Injection, agalsidase beta, 1 mgBilling unit “1 MG” from the CMS payment limit file (Q4 2026) — official.

One billing unit equals

From the HCPCS descriptor, e.g. “10 mg” for “Injection, rituximab, 10 mg”.

2 · Dose administered

Dose

The amount given to the patient for this line.

3 · Container (optional)

NDC used

Packages CMS crosswalks to J0180. Choosing one fills the amount per container and, when the FDA package text states it, the container type.

Drug amount per vial or package item

Containers opened

Blank uses the minimum needed for the dose.

Known discarded amount

Optional. Overrides the container-based estimate.

Container type

Single-doseMulti-doseNot sure

4 · Payment limit (optional)

Medicare payment limit per billing unit

CMS Part B payment limit Q4 2026 (per 1 MG). Edit or clear as needed.

Results update as you type.

Result

Enter the billing unit and the dose to see HCPCS units, the formula, and any discarded quantity.

Verify before billing

Payer rules and claim requirements must be verified. This calculator applies arithmetic conventions described in Medicare instructions — whole units, rounded up when a dose is not a multiple of the descriptor — and other payers may differ.

About discarded-drug modifiers (educational): for separately payable Part B drugs from single-dose containers, Medicare instructions describe reporting discarded amounts on a separate line with the JW modifier and using the JZ modifier when nothing was discarded. CodeRx does not determine whether a modifier applies to your claim. Check the current CMS discarded drugs guidance, your MAC, and the payer.

Vial optimizer

The combination of container sizes that leaves the least drug unused, and whole-container doses within a rounding threshold. Sizes come from the CMS NDC crosswalk for this code (billable units per item × billing unit).

Container sizes stocked

5 mgGenzyme Corporation · 1 NDC
35 mgGenzyme Corporation · 1 NDC

Other sizes (mg, optional)

Rounding threshold (±%)

Use your institution’s policy. The HOPA 2017 position statement recommends rounding monoclonal antibodies and other biologics to the nearest vial within 10%.

Enter a dose above to see container combinations.

Disclaimer. This application provides informational coding and reimbursement reference data. It does not constitute legal, clinical, coding, or billing advice. Codes, payment amounts, payer rules, and coverage policies can change. Verify all information with current CMS publications, the applicable payer, and your organization’s compliance policies before submitting a claim. CodeRx is not affiliated with or endorsed by CMS, FDA, Medicare, or any payer.