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How-to · reconstitution
Put 1 mL of bacteriostatic water into the 5 mg Semaglutide vial. That makes 5.00 mg/mL. A 0.25 mg dose is then 5.0 units on a U-100 syringe.
That volume is the one that lands the draw on a syringe line, so the reading can be checked by eye. More water makes a weaker mix and a bigger draw. Less water makes a stronger mix and a smaller one. The amount of Semaglutide in the glass never changes. Only the number of marks it takes does.
Semaglutide is the drug in Wegovy, Ozempic and Rybelsus. It copies a gut hormone called GLP-1, which helps control appetite and blood sugar.
| Water added | Concentration | Per U-100 unit | Example: 0.25 mg = |
|---|---|---|---|
| 1 mL | 5.00 mg/mL | 50 mcg | 5.0 units |
| 2 mL | 2.50 mg/mL | 25 mcg | 10.0 units |
Straight arithmetic: concentration = 5 mg ÷ water, and 1 U-100 unit = 0.01 mL. The example column shows the math at 0.25 mg; it is not a dose recommendation.
Which volume to use is a practical choice rather than a dose. Pick the one that puts your draw somewhere you can actually read it on the syringe. The flags in the last column mark where that fails. “Hard to measure” means the draw is too small to judge by eye. “Won’t fit” means it is bigger than one U-100 syringe holds.
The table above uses one worked example. These are the published quantities, converted into marks on a U-100 barrel at each water volume for a 5 mg vial. Where a quantity was never studied by injection, the row says so.
0.25 mg once weekly for 4 weeks, under the skin.
| Water added | Concentration | Draw |
|---|---|---|
| 1 mL | 5.00 mg/mL | 5.0 units |
| 2 mL | 2.50 mg/mL | 10.0 units |
FDA labelWegovy (semaglutide) — FDA-approved Prescribing Information (DailyMed) · retrieved 2026-08-20
1.7–2.4 mg once weekly, under the skin.
| Water added | Concentration | Draw, low to high |
|---|---|---|
| 1 mL | 5.00 mg/mL | 34.0 to 48.0 units |
| 2 mL | 2.50 mg/mL | 68.0 to 96.0 units |
FDA labelWegovy (semaglutide) — FDA-approved Prescribing Information (DailyMed) · retrieved 2026-08-20
At the worked amount, about four fifths of this vial remains after the stated storage window. The dose count alone does not reveal that waste.
The powder is fine. The clock is what expires, and it starts the moment water goes in rather than when the vial was bought.
Priced per dose you can actually use, the middle vial in this family is several times what the milligram price suggests.
This is the easiest semaglutide vial to read: each water option lands the worked dose exactly on a syringe line.
The smaller volume puts it at a handful of units, though, where one mark is a fifth of the dose. Tidy and checkable are not the same thing, and the larger reading is the one you can confirm by eye.
Neither of the other two semaglutide sizes manages both. Each of them has one listed volume that leaves the plunger between graduations, so this is the middle vial in more than size.
Against the top of the labeled schedule this vial holds two weeks rather than five months. It clears the window with nothing left in the glass.
The wastage above belongs to the opening step of the schedule, not to the vial.
The table shows the offered water volumes. The calculator does the same arithmetic for any volume and any syringe, and shows its working line by line.
Open the Semaglutide calculator →The arithmetic on this page is only half the question. These are the pages that carry the other half.