Semaglutide 20 mg vial
How much bacteriostatic water to add to a 20 mg vial of Semaglutide, the syringe units for each common dose, and how many doses the vial holds.
- Water
- 2 mL
- Strength
- 10 mg/mL
- Common dose
- 0.25 mg
- Draw
- 2.5 units0.025 mL
- Doses per vial
- 80
The short answer
Mixed with 2 mL of bacteriostatic water, a 20 mg vial of Semaglutide holds 10 mg/mL. A 0.25 mg dose is then 2.5 units (0.025 mL) on a U-100 insulin syringe, and the vial holds about 80 doses of that size. Taken 1× per week, it lasts about 80 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 0.25 mg |
|---|---|---|---|
| 1 mL | 20 mg/mL | 200 mcg | 1.3 units (0.013 mL) |
| 2 mL | 10 mg/mL | 100 mcg | 2.5 units (0.025 mL) |
| 3 mL | 6.667 mg/mL | 66.7 mcg | 3.8 units (0.037 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 | |
| 0.25 mg | |||
| 0.5 mg | |||
| 1 mg | |||
| 1.7 mg | |||
| 2.4 mg | |||
| 7.2 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 Start at 0.25 mg once weekly and step up every 4 weeks to a 2.4 mg maintenance dose (1.7 mg is an alternative). For weight reduction, adults may go to 7.2 mg after at least 4 weeks at 2.4 mg.
- Label 0.25 mg weekly for 4 weeks, then 0.5 mg. Increase to 1 mg and then 2 mg (maximum) only if needed, each after at least 4 weeks.
Doses are what labels, trials or community reports reference, not recommendations. Semaglutide’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. Branded pens have their own room-temperature windows on the label.
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 semaglutide?
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 0.25 mg of semaglutide?
With 2 mL in a 20 mg vial, 0.25 mg is 2.5 units (0.025 mL) on a U-100 insulin syringe. With 1 mL, 1.3 units (0.013 mL); with 3 mL, 3.8 units (0.037 mL).
How many doses are in a 20 mg vial of semaglutide?
About 80 doses of 0.25 mg, or 8 of 2.4 mg or 2 of 7.2 mg. Taken 1× per week at 0.25 mg, it lasts about 80 weeks.
How long does a mixed vial of semaglutide keep?
Mixed vials: 2–8 °C, protected from light. Branded pens have their own room-temperature windows on the label.
Other vial sizes
Sources
- Wegovy prescribing information, rev. 06/2026 (Novo Nordisk)
- Ozempic label (DailyMed)
- Rybelsus and Ozempic tablets prescribing information, rev. 01/2026 (Novo Nordisk, DailyMed)
- FDA alert: dosing errors with compounded semaglutide (2024)
The math on this page uses the doses and storage on Semaglutide’s page.