Semaglutide reconstitution calculator
How many units of a reconstituted semaglutide vial make up the dose you want — and how much bacteriostatic water to add to land on a round number. Same code as the TherapyLog app, no account needed.
Semaglutide is the reconstitution question people get wrong most often, and the reason is the unit. Approved semaglutide is prescribed in milligrams per week — 0.25 to 2.4 mg — while the syringe most people are holding is marked in insulin units, of which there are a hundred to the millilitre. A tenth of a millilitre is ten units, and at a typical reconstitution a tenth of a millilitre is a quarter of a milligram. Getting that mapping wrong by one decimal place is a tenfold dosing error, in either direction.
The other thing worth knowing before you mix: semaglutide's modelled half-life is about seven days, so a dose does not clear between weekly injections and levels build for roughly five weeks before they plateau. That is what the four-week titration steps in the approved labelling are pacing. A dose that felt fine in week one can feel very different in week five without anything having changed but accumulation.
Semaglutide milligrams to insulin units
Computed for a 5 mg vial reconstituted in 2 ml of bacteriostatic water, which gives 2.50 mg per ml (2,500 mcg/ml), read off a U-100 syringe. The steps are the approved titration steps for the obesity indication (0.25, 0.5, 1.0, 1.7, 2.4 mg weekly) — they are what the numbers are indexed to, not advice about which one applies to anyone. Change the vial or the water above and every figure moves; the calculator is the authority, this table is the common case.
| Semaglutide dose | Volume to draw | On a U-100 syringe |
|---|---|---|
| 250 mcg | 0.1 ml | 10 units |
| 500 mcg | 0.2 ml | 20 units |
| 1 mg | 0.4 ml | 40 units |
| 1.7 mg | 0.68 ml | 68 units |
| 2.4 mg | 0.96 ml | 96 units |
Why semaglutide is reconstituted the way it is
Semaglutide arrives as a lyophilised powder in vials that are usually labelled 2, 5 or 10 mg, and it is reconstituted rather than sold pre-mixed because the peptide is markedly more stable dry than in solution. Bacteriostatic water is the usual diluent specifically because its benzyl alcohol lets a mixed vial be entered repeatedly over weeks rather than once — which matters when a 5 mg vial holds twenty 0.25 mg doses.
Because it is dosed weekly, the arithmetic only has to be done once per vial: pick a diluent volume that puts your dose on a round number of units, write the concentration on the vial, and read the same number off the syringe every week until the titration step changes.
What the app knows about Semaglutide
Generated from the same entry the app's encyclopedia reads, so this page and the app cannot disagree about it.
- Also known as
- Ozempic, Wegovy
- Class
- GLP-1 / Metabolic
- Modelled half-life
- 7 days
- Time to peak
- 40 h
- Formulation
- Aqueous (reconstituted powder)
- Regulatory status
- FDA APPROVED for T2 diabetes (Ozempic) and obesity (Wegovy). Off-label for general weight loss.
- Monitoring panel
- HbA1c, fasting glucose, lipids, amylase if abdominal pain, weight monthly.
- Before mixing
- Sealed powder tolerates room temperature in transit, but keep it refrigerated at 2–8 °C (36–46 °F) for anything beyond a few weeks, or frozen for months. Keep it dark — the carton it shipped in is doing a job.
- After mixing
- Once reconstituted with bacteriostatic water: refrigerate at 2–8 °C and use within about 28 days. The benzyl alcohol in bacteriostatic water is what buys that window — plain sterile water has no preservative, so a vial mixed with it should be treated as one sitting only. Kits are usually ten vials: only the one you mixed is on that 28-day clock — the sealed ones keep their own, much longer shelf life, so store them as powder, not as solution.
- What ruins it
- Do not freeze a reconstituted vial. Repeated freeze–thaw is one of the more reliable ways to degrade a peptide.
- Handling caveat
- General handling practice for this formulation. Your supplier’s own insert or COA overrides anything here.
Dosing rows from that entry
Established clinical use These are the schedules the entry records, reproduced so you can see what the milligram figures above are indexed to. Which one applies to a particular person is a prescribing decision, and this page does not make it.
| Label | Amount | Route and frequency |
|---|---|---|
| Starting | 0.25mg/week | Weekly SubQ |
| Maintenance | 0.5-1.0mg/week | Weekly SubQ |
| Max (Wegovy) | 2.4mg/week | Weekly SubQ |
How the math works
volume to draw = dose (mcg) ÷ 2,500 mcg/ml
units (U-100) = volume to draw (ml) × 100
The rules built into the calculator: a practical draw lands on a half-unit and is at least two units; U-100 means a hundred units per millilitre, so 0.1 ml is 10 units on any U-100 syringe regardless of its barrel size; and a draw that exceeds the barrel is flagged rather than silently split across injections.
Questions people ask about semaglutide reconstitution
How many units is 250 mcg of semaglutide?
At 5 mg in 2 ml — 2,500 mcg/ml — it is 10 units on a U-100 syringe. At any other reconstitution it is a different number, which is why the table above states the vial and the diluent volume it was computed for.
What size vial should I reconstitute?
Whichever one you have — the calculator takes the strength as an input. What the vial size decides is how many doses it holds, and therefore whether it will still be good when you reach the last one: a 5 mg vial holds about 2 of the largest step above, and about 20 of the smallest. A vial holding more doses than its post-mixing window allows is a vial you will be throwing part of away, which is an argument for mixing a smaller working volume rather than a bigger one.
Does semaglutide accumulate between doses?
Its modelled half-life is 7 days. A rough guide is that levels keep building for about five half-lives before they plateau, so the effect of a dose you take today is partly the effect of the doses before it. The Semaglutide half-life page shows the curve and the steady-state arithmetic.
How long does it keep once mixed?
The entry's handling rule is in the fact box above, along with the caveat that comes with it: your supplier's own insert or certificate of analysis overrides anything generic. As a rule the constraint is the diluent rather than the peptide — bacteriostatic water's preservative is what makes repeated entry reasonable, and it is the reason a mixed vial is a weeks-not-months proposition.
Related: Semaglutide half-life and steady state, the generic reconstitution calculator, and the insulin syringe unit converter.
The app stores this vial's strength, its concentration and the date you mixed it, and counts the doses down as you log them.
Save this dose to your logThis calculator does the arithmetic you typed and nothing else. It does not know what is actually in your vial, whether the label is accurate, or anything about you. Confirm the vial strength and the diluent volume on your own label before you draw, and take dosing decisions to a qualified provider.