Zepbound Vial Calculator for Single-Dose and Multi-Dose Vials

1. Choose the vial type on your box: single-dose (0.5 mL) or multi-dose (2.4 mL, four doses).
2. Choose the strength per dose, from 2.5 mg to 15 mg. A multi-dose carton prints the whole vial in large type, such as 60 mg/2.4 mL (25 mg/mL), and the dose on a separate line: "Contains 4 doses of 15 mg/0.6 mL" (Zepbound prescribing information, package label). Pick the per-dose figure.
3. Read the line to draw to for a full dose. If your prescriber gave you a different amount in mg, enter it to get its units. If you have already drawn, enter the units in the syringe to see the mg it holds and its share of the labeled dose.
4. For a multi-dose vial, add the date of your first dose to get the four dose dates and the date to throw the vial away, which you can print, save as an image or add to your calendar.

The calculator divides the strength per dose by the dose volume to get the concentration, then multiplies by the volume you drew: mg in the syringe = units ÷ 100 × (strength per dose ÷ dose volume in mL). On a U-100 syringe, 100 units fill 1 mL, and FDA describes a 5-unit dose as 0.05 mL (FDA alert on compounded semaglutide dosing errors), so 1 unit is 0.01 mL.

Take the 60 mg/2.4 mL multi-dose vial, which holds four 15 mg/0.6 mL doses (Zepbound prescribing information, section 3). Its concentration is 60 ÷ 2.4 = 25 mg/mL, and the full 0.6 mL dose is 60 units, or 15 mg. Drawing 50 units out of single-dose habit puts 0.5 mL × 25 mg/mL = 12.5 mg in the syringe, which is 83% of the dose.

A single-dose vial holds one 0.5 mL dose and is thrown away after that use, and a multi-dose vial holds four 0.6 mL doses (Zepbound prescribing information, sections 3 and 16); How many mL are in a Zepbound vial compares the two in full.

Each multi-dose strength holds its dose in 0.6 mL, so the concentration is the strength ÷ 0.6 (Zepbound prescribing information, section 3). The last column is what a 50-unit draw holds at that concentration.

Four 0.5 mL draws use 2.0 mL of the 2.4 mL, so about 0.4 mL is still in the vial after the fourth dose. Enter 50 units for a multi-dose vial and the calculator shows that leftover volume as a warning. If your vial has that much left when its four doses are done, check which line you have been drawing to.

The calculator covers branded Zepbound and Mounjaro vials only. A compounded tirzepatide vial has whatever concentration its pharmacy label states, so use the tirzepatide dose calculator for it. When a compounded refill arrives at a different strength, the vial transition calculator keeps your dose in mg and gives the new unit count.

On branded vials the draw does not change when your dose does. Moving from 5 mg to 7.5 mg means a stronger vial drawn to the same 0.5 mL or 0.6 mL line; the steps themselves are set out in the Zepbound dose ladder.