Semaglutide Reconstitution Calculator
Enter your semaglutide vial size, the bacteriostatic water you added, and your provider-directed dose. Get the exact insulin-syringe units to draw — live on the syringe below — plus the FDA-label titration schedules for reference. It’s the same math built into the PeptideWiz app.
Common vial sizes
Common provider-directed doses
To draw a dose of 0.25 mg, pull the plunger to 10.0 units.
Not medical advice. This calculator performs arithmetic on the numbers you enter. It does not recommend a dose, confirm that semaglutide or any protocol is safe or appropriate for you, or replace your provider. Always verify everything with a licensed medical professional.
Semaglutide mixing quick-reference
The water volume you add sets the concentration — it never changes the dose itself, only how big the draw is on the syringe. Here’s how a 5 mg vial reads on a U-100 insulin syringe at three common water volumes:
| Water added | Concentration | 0.25 mg dose | 0.5 mg dose | 1 mg dose |
|---|---|---|---|---|
| 1 mL | 5,000 mcg/mL | 5 units | 10 units | 20 units |
| 2 mL | 2,500 mcg/mL | 10 units | 20 units | 40 units |
| 3 mL | 1,667 mcg/mL | 15 units | 30 units | 60 units |
Using a 2.5 mg or 10 mg vial? Tap the preset above — the calculator redoes every number instantly.
Semaglutide titration schedules (FDA label, for reference)
Branded semaglutide is titrated stepwise so the body can adjust. These are the FDA-approved schedules for Wegovy and Ozempic, shown for reference only — compounded semaglutide dosing varies, and your prescriber’s plan always takes precedence.
Wegovy (weight management) — once weekly
4-week steps up to the maintenance dose.
| Weeks | Weekly dose | Units at 2,500 mcg/mL |
|---|---|---|
| 1–4 | 0.25 mg | 10 units |
| 5–8 | 0.5 mg | 20 units |
| 9–12 | 1 mg | 40 units |
| 13–16 | 1.7 mg | 68 units |
| 17+ (maintenance) | 2.4 mg | 96 units |
Ozempic (type 2 diabetes) — once weekly
Increases only if more glycemic control is needed.
| Weeks | Weekly dose | Units at 2,500 mcg/mL |
|---|---|---|
| 1–4 | 0.25 mg (starter, not for glycemic control) | 10 units |
| 5+ | 0.5 mg | 20 units |
| If needed | 1 mg | 40 units |
| Maximum | 2 mg | 80 units |
The units column assumes a 5 mg vial with 2 mL of bacteriostatic water (2,500 mcg/mL). A different vial or water volume changes every unit figure — use the calculator above with your own numbers.
How to reconstitute a semaglutide vial
- Gather supplies. The lyophilized semaglutide vial, bacteriostatic water, a sterile mixing syringe, alcohol wipes, and your insulin syringes.
- Sanitize. Wash your hands and wipe both vial stoppers with a fresh alcohol wipe.
- Draw the water. Pull your chosen volume (for example 2 mL) into the mixing syringe — that volume sets the concentration, so enter the same number in the calculator above.
- Add it slowly. Let the water run gently down the inside wall of the vial. Don’t jet it straight onto the powder.
- Swirl, don’t shake. Gently swirl until the solution is completely clear — shaking can degrade peptides.
- Label and refrigerate. Write the date and concentration on the vial, store it cold, and track doses, remaining volume, and the reconstitution date in the PeptideWiz app.
Full walkthrough: How to reconstitute peptides, step by step →
How the calculation works
vial (mcg) ÷ water (mL)
How much semaglutide is in every millilitre after reconstitution.
dose (mcg) ÷ concentration
The millilitres that contain exactly your dose.
mL × 100
A U-100 insulin syringe holds 100 units per millilitre.
Worked example: a 5 mg vial (5,000 mcg) with 2 mL of water gives 2,500 mcg/mL. A 0.25 mg (250 mcg) dose is 250 ÷ 2,500 = 0.1 mL, and 0.1 × 100 = 10 units — with 20 such doses in the vial.
Frequently asked questions
How much bacteriostatic water should I add to a 5 mg semaglutide vial?
There’s no single correct volume — water only sets the concentration, not the dose. 2 mL gives 2,500 mcg/mL, so a 0.25 mg dose is a clean 10-unit draw. Pick a volume that makes your provider-directed dose land on easy-to-read syringe marks; the calculator lets you compare instantly.
How many units is 0.25 mg of semaglutide?
It depends entirely on your vial’s concentration. At 2,500 mcg/mL (5 mg vial + 2 mL water) it’s 10 units; at 5,000 mcg/mL (same vial + 1 mL) it’s 5 units. Never reuse someone else’s unit figure — calculate from your own vial and water volume.
Does semaglutide from a vial dose differently than the pens?
Branded pens are pre-concentrated and click to fixed doses. A compounded or research vial requires reconstitution, so the same milligram dose can be a different number of syringe units depending on how it was mixed — which is exactly what this page calculates.
Can PeptideWiz remind me of my weekly injection day?
Yes — the PeptideWiz app schedules weekly (or any interval) reminders, logs each injection with site rotation, tracks side effects and weight, and keeps a running vial inventory with expiration alerts.
Track your semaglutide protocol in the PeptideWiz app →
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