Tirzepatide 20 mg vial
How much bacteriostatic water to add to a 20 mg vial of Tirzepatide, the syringe units for each common dose, and how many doses the vial holds.
- Water
- 2 mL
- Strength
- 10 mg/mL
- Common dose
- 2.5 mg
- Draw
- 25 units0.25 mL
- Doses per vial
- 8
The short answer
Mixed with 2 mL of bacteriostatic water, a 20 mg vial of Tirzepatide holds 10 mg/mL. A 2.5 mg dose is then 25 units (0.25 mL) on a U-100 insulin syringe, and the vial holds about 8 doses of that size. Taken 1× per week, it lasts about 8 weeks.
How much water
The water only sets the strength; the dose and the number of doses in the vial stay the same. Draws are on a U-100 insulin syringe, where 1 unit is 0.01 mL.
| Water added | Strength | Per syringe unit | Draw for 2.5 mg |
|---|---|---|---|
| 1 mL | 20 mg/mL | 200 mcg | 12.5 units (0.13 mL) |
| 2 mL | 10 mg/mL | 100 mcg | 25 units (0.25 mL) |
| 3 mL | 6.667 mg/mL | 66.7 mcg | 37.5 units (0.38 mL) |
Dose chart
Syringe units for each common dose at each water volume. Select a cell to open it in the calculator.
| Dose | Water added | ||
|---|---|---|---|
| 1 mL | 2 mL | 3 mL | |
| 2.5 mg | |||
| 5 mg | |||
| 7.5 mg | |||
| 10 mg | |||
| 12.5 mg | |||
| 15 mg | |||
Draws over 100 units show in mL. Faded values are under 2 units, which is hard to measure. Check that your vial holds the larger volumes.
Where the doses come from
- Label 2.5 mg once weekly for 4 weeks, then 5 mg. Further 2.5 mg steps come after at least 4 weeks on the current dose. Zepbound maintenance is 5, 10 or 15 mg for weight and 10 or 15 mg for sleep apnea; Mounjaro steps up only if blood sugar needs it. Maximum 15 mg (10 mg for children on Mounjaro).
Doses are what labels, trials or community reports reference, not recommendations. Tirzepatide’s page has the cycle, side effects, cautions and sources.
Mixing and storage
- PrepareLet a refrigerated vial come to room temperature, and wipe both stoppers with an alcohol swab.
- Add 2 mLDraw 2 mL of bacteriostatic water and let it run slowly down the inside wall of the vial.
- Swirl, don’t shakeSwirl gently until the powder dissolves and the liquid is clear.
- Label itWrite the date and the strength, 10 mg/mL, on the vial.
Storage: Mixed vials: 2–8 °C, protected from light. Don’t freeze.
The reconstitution guide covers each step, and the units page explains syringe markings.
Questions
How much water do I add to a 20 mg vial of tirzepatide?
There’s no single right amount: the water only sets the strength. With 2 mL of bacteriostatic water, a 20 mg vial holds 10 mg/mL. With 1 mL it’s 20 mg/mL; with 3 mL it’s 6.667 mg/mL. Less liquid makes each dose a smaller draw; more makes small doses easier to measure.
How many units is 2.5 mg of tirzepatide?
With 2 mL in a 20 mg vial, 2.5 mg is 25 units (0.25 mL) on a U-100 insulin syringe. With 1 mL, 12.5 units (0.13 mL); with 3 mL, 37.5 units (0.38 mL).
How many doses are in a 20 mg vial of tirzepatide?
About 8 doses of 2.5 mg, or 1 of 12.5 mg or 1 of 15 mg. Taken 1× per week at 2.5 mg, it lasts about 8 weeks.
How long does a mixed vial of tirzepatide keep?
Mixed vials: 2–8 °C, protected from light. Don’t freeze.
Other vial sizes
Sources
- Zepbound prescribing information, rev. 08/2026 (Eli Lilly)
- Mounjaro prescribing information, rev. 08/2026 (Eli Lilly)
The math on this page uses the doses and storage on Tirzepatide’s page.