Reconstitution Calculator
How Much Bacteriostatic Water Do I Add?
Enter your vial details below. Results update instantly with exact volumes and per-dose draw amounts.
Mixing Instructions
Step-by-Step Reconstitution Guide
Follow these steps exactly each time you reconstitute a new vial. Complete the calculator above first to get your personalized water volume.
- Semaglutide powder vial (from your compounding pharmacy)
- Bacteriostatic water for injection (NOT sterile water — must be bacteriostatic)
- 1 mL or 3 mL syringe with needle for drawing water
- Insulin syringe for dosing (U-100 or U-40 as prescribed)
- Alcohol swabs (70% isopropyl)
- Clean, flat surface
Wash your hands thoroughly
Use soap and water for at least 20 seconds. Dry with a clean towel. This is the single most important contamination-prevention step.
Swab both vial tops with alcohol
Clean the rubber stopper of your semaglutide vial and your bacteriostatic water vial with separate alcohol swabs. Let both air dry for 10–15 seconds — do not blow on them or fan them.
Draw the bacteriostatic water
Using your drawing syringe, pull back the plunger to your calculated water volume, then insert the needle into the bacteriostatic water vial and draw up that amount.
Inject water slowly into the semaglutide vial
Insert the needle into the semaglutide vial at an angle so the water runs down the side of the vial — not directly onto the powder. Inject slowly. Never force the plunger.
Do NOT shake the vial
Shaking can damage the peptide structure. Instead, gently swirl the vial in slow circles for 30–60 seconds until the powder is fully dissolved. The solution should be clear and colorless.
Inspect the solution
Hold the vial up to light. The reconstituted solution should be clear and colorless with no visible particles. If it looks cloudy, discolored, or has floating particles — do not use it. Contact your pharmacy.
Label and refrigerate immediately
Write today's date on the vial. Store immediately in the refrigerator at 36–46°F (2–8°C). Do not freeze. Reconstituted semaglutide is typically stable for 28 days refrigerated — confirm with your pharmacy.
Reference Table
Common Reconstitution Volumes
Quick reference for the most common vial sizes and target concentrations. Always verify with your pharmacy.
| Vial Size | Target Conc. | Bac. Water to Add | 0.25 mg dose = Units (U-100) |
|---|---|---|---|
| 2 mg | 2 mg/mL | 1.0 mL | 12.5 units |
| 2 mg | 2.5 mg/mL | 0.8 mL | 10 units |
| 3 mg | 2.5 mg/mL | 1.2 mL | 10 units |
| 5 mg | 2.5 mg/mL | 2.0 mL | 10 units |
| 5 mg | 5 mg/mL | 1.0 mL | 5 units |
| 10 mg | 5 mg/mL | 2.0 mL | 5 units |
| 10 mg | 10 mg/mL | 1.0 mL | 2.5 units |