Semaglutide Reconstitution Calculator — 5mg and 10mg Vials
For research use only — not clinical guidance.
Calculator: Find Your Syringe Units
Enter your vial size and diluent volume below. The calculator outputs stock concentration, mcg per U-100 unit, and syringe units for common research volumes.
| Vial Size | Diluent Volume | Stock Concentration | mcg per Unit (U-100) | Units for 250 mcg | Units for 500 mcg | Units for 1000 mcg | |-----------|----------------|---------------------|----------------------|-------------------|-------------------|--------------------| | 5mg | 1 mL | 5000 mcg/mL | 50 mcg | 5 units | 10 units | 20 units | | 5mg | 2 mL | 2500 mcg/mL | 25 mcg | 10 units | 20 units | 40 units | | 5mg | 3 mL | 1667 mcg/mL | 16.7 mcg | 15 units | 30 units | 60 units | | 10mg | 1 mL | 10,000 mcg/mL | 100 mcg | 2.5 units | 5 units | 10 units | | 10mg | 2 mL | 5000 mcg/mL | 50 mcg | 5 units | 10 units | 20 units | | 10mg | 3 mL | 3333 mcg/mL | 33.3 mcg | 7.5 units | 15 units | 30 units |
How to read: Find your vial size in the left column. Pick your diluent volume. The table gives you concentration and exact syringe units for common research volumes. For any other target, use the formula below.
Reconstitution Math — Step by Step
The Formula
Concentration (mcg/mL) = Peptide mass (mcg) ÷ Diluent volume (mL)
Convert mg to mcg first:
- 5mg = 5000 mcg
- 10mg = 10,000 mcg
Example: 5mg peptide + 2mL bacteriostatic water
5000 mcg ÷ 2 mL = 2500 mcg/mL
That's your stock concentration.
What That Means on a U-100 Insulin Syringe
A U-100 insulin syringe has 100 units. Each unit = 0.01 mL. This is fixed per ISO 8536-4 and FDA labeling requirements.
At 2500 mcg/mL, one unit (0.01 mL) contains:
2500 mcg/mL × 0.01 mL = 25 mcg per unit
Want 250 mcg? Draw 10 units. Want 500 mcg? Draw 20 units.
Common Failure Mode
Adding 1 mL to a 5mg vial gives 5000 mcg/mL. That's 50 mcg per unit. But 1 mL fills the entire syringe (100 units) — no room for air bubbles or vial dead volume. Use 2 mL or more for practical handling.
Practical Reconstitution Steps
Step 1: Gather materials
- Semaglutide vial (5mg or 10mg)
- Bacteriostatic water (0.9% benzyl alcohol, USP <71> compliant)
- Alcohol swab
- U-100 insulin syringe (0.3 mL, 0.5 mL, or 1 mL — choose based on target volume)
- Vial adapter (optional but reduces coring)
Step 2: Prepare the vial Wipe the rubber stopper with an alcohol swab. Let it dry 15 seconds. Alcohol degrades peptide if injected wet.
Step 3: Inject diluent Draw your chosen volume of bacteriostatic water into the syringe. Inject slowly against the inner wall of the vial — not directly onto the lyophilized powder. Direct jetting can denature the peptide.
Step 4: Swirl, don't shake Gently swirl until powder fully dissolves. Shaking creates foam and can shear peptide chains. If foam appears, let vial sit 5 minutes.
Step 5: Calculate your dose Use the table above or the formula. Draw the correct units on your U-100 syringe.
Step 6: Store properly Reconstituted semaglutide is stable 14-28 days at 2-8°C (refrigerated). Do not freeze. Discard after 28 days per USP <797> guidelines for multi-dose vials.
Syringe Unit Conversion Reference
U-100 insulin syringe conversions in plain numbers.
| Syringe Units | Volume (mL) | Volume (mcg at 2500 mcg/mL) | |---------------|-------------|------------------------------| | 1 unit | 0.01 mL | 25 mcg | | 5 units | 0.05 mL | 125 mcg | | 10 units | 0.1 mL | 250 mcg | | 20 units | 0.2 mL | 500 mcg | | 30 units | 0.3 mL | 750 mcg | | 40 units | 0.4 mL | 1000 mcg | | 50 units | 0.5 mL | 1250 mcg | | 100 units | 1.0 mL | 2500 mcg |
Note: mcg-per-unit changes with dilution. This example uses 2500 mcg/mL (5mg in 2 mL). For other dilutions, recalculate.
Common Mistakes and How to Avoid Them
Mistake 1: Using the wrong syringe U-100 insulin syringes measure in units, not mL. If using a 1 mL tuberculin syringe marked in mL, convert: 0.01 mL = 1 unit. Don't mix them.
Mistake 2: Adding too little diluent 1 mL in a 5mg vial = 5000 mcg/mL = 50 mcg per unit. For 250 mcg, you draw 5 units — tiny and hard to measure accurately. Use 2 mL or more for better precision.
Mistake 3: Not accounting for dead volume Vials retain about 0.05-0.1 mL after you draw. For exact volumes, account for this. Use a vial adapter that minimizes dead space.
Mistake 4: Shaking the vial Lyophilized peptides are fragile. Shaking introduces air bubbles and can break peptide bonds. Swirl gently. If foam appears, wait.
Mistake 5: Storing at room temperature Reconstituted semaglutide degrades at room temperature. Refrigerate at 2-8°C. Do not freeze — ice crystals damage peptide structure.
Where to Source Bacteriostatic Water
Need sterile bacteriostatic water with 0.9% benzyl alcohol. Must meet USP <71> sterility standards and USP <85> bacterial endotoxin limits.
- BAC Water Depot — USP-grade, 30 mL vials, ISO 9001:2015 facility
- Peptide Sciences — 0.9% benzyl alcohol, sterile-filtered
- Limitless Life — 30 mL multi-dose vial
Always verify lot number and expiration date before use. Discard any vial with visible particulate or cloudiness.
Disclaimer: For research use only — not clinical guidance. Semaglutide is a controlled research peptide. Consult your institutional review board and follow all applicable regulations. The math and methods described are for laboratory use with U-100 insulin syringes and USP-grade diluents.