Semaglutide Reconstitution Calculator
BAC water, concentration & dose-to-units charts
Work out how much bacteriostatic water to add to a semaglutide vial and what each dose becomes in syringe units, using the charts below — for example, a 5 mg vial in 2 mL of water is 2.5 mg/mL, so a 0.5 mg dose is 0.2 mL, or 20 units on a U-100 syringe. Compounded semaglutide is not the same as branded Ozempic or Wegovy; always confirm against the product label and your prescriber.
How semaglutide reconstitution works
Compounded or research semaglutide is supplied as a freeze-dried (lyophilized) powder that you dissolve with bacteriostatic water before measuring a dose. The concentration is the vial strength divided by the water you add — a 5 mg vial in 2 mL of water is 2.5 mg/mL.
Once you know the concentration, your dose volume is the dose divided by the concentration, and on a U-100 insulin syringe that volume × 100 gives the unit marks to draw. Because semaglutide doses are small (0.25–2.4 mg), a lower concentration usually gives a more measurable number of units — remember 0.25 mg is the same as 250 mcg.
Reconstitution chart: concentration by semaglutide vial size and water added
| Vial size | +1 mL | +2 mL | +3 mL | +5 mL |
|---|---|---|---|---|
| 2 mg | 2 mg/mL | 1 mg/mL | 0.67 mg/mL | 0.4 mg/mLBest |
| 5 mg | 5 mg/mL | 2.5 mg/mL | 1.67 mg/mL | 1 mg/mL |
| 10 mg | 10 mg/mL | 5 mg/mL | 3.33 mg/mL | 2 mg/mL |
| 15 mg | 15 mg/mL | 7.5 mg/mL | 5 mg/mL | 3 mg/mL |
Semaglutide dose to syringe units (by concentration)
| Weekly dose | 1 mg/mL | 2.5 mg/mL | 5 mg/mL |
|---|---|---|---|
| 0.25 mg (250 mcg) | 0.25 mL → 25 | 0.1 mL → 10 | 0.05 mL → 5Best |
| 0.5 mg (500 mcg) | 0.5 mL → 50 | 0.2 mL → 20 | 0.1 mL → 10 |
| 1.0 mg | 1.0 mL → 100 | 0.4 mL → 40 | 0.2 mL → 20 |
| 1.7 mg | 1.7 mL → 170* | 0.68 mL → 68 | 0.34 mL → 34 |
| 2.0 mg | 2.0 mL → 200* | 0.8 mL → 80 | 0.4 mL → 40 |
| 2.4 mg | 2.4 mL → 240* | 0.96 mL → 96 | 0.48 mL → 48 |
How to reconstitute a semaglutide vial
Dosing, storage & safety
Semaglutide is dosed once weekly and titrated slowly from 0.25 mg to reduce nausea, typically reaching 1.7–2.4 mg for weight management. This calculator only does the reconstitution and unit math; your titration schedule should come from a clinician and the prescribing information.
Bacteriostatic water contains benzyl alcohol as a preservative, so a reconstituted vial can be used for multiple draws; keep it refrigerated and labeled with its concentration and date. Compounded semaglutide is not FDA-evaluated for identity or potency the way branded pens are — including products formulated as semaglutide salts — so only obtain and use it under appropriate medical supervision and confirm doses with your pharmacist.
Frequently Asked Questions
5 mg in 1 mL is 5 mg/mL; in 2 mL is 2.5 mg/mL; in 5 mL is 1 mg/mL. Because semaglutide doses are small, a lower concentration (more water) usually makes the units easier to measure. Use the reconstitution chart above.
At 2.5 mg/mL, 0.25 mg (250 mcg) is 0.1 mL, or 10 units on a U-100 insulin syringe. At 1 mg/mL it is 0.25 mL (25 units). Units = (dose ÷ concentration) × 100.
First convert mcg to mg (1000 mcg = 1 mg), then divide by your concentration and multiply by 100. Example: 500 mcg = 0.5 mg; at 5 mg/mL that is 0.1 mL, or 10 units.
No. Branded Ozempic and Wegovy come premeasured in pens and require no mixing. Reconstitution only applies to vialed or compounded semaglutide powder.
Because doses are small, 1–2.5 mg/mL usually gives the most readable number of units for 0.25–1 mg doses, while 5 mg/mL keeps higher 2–2.4 mg doses under a full syringe.
Yes. Shotlee stores your vial concentration, logs each weekly dose and side effect, and sends reminders so you do not have to recompute. It is free.
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