Peptide Reconstitution Calculator
Calculate the exact concentration after reconstituting your peptide vial with bacteriostatic water. See how much to draw and how long the vial will last.
Common protocols (click to auto-fill)
Use 0.143 for once/week, 0.286 for twice/week
Your results
Draw to here
10 units
on 100-unit syringe
Concentration
5,000 mcg/mL
(5.00 mg/mL)
Volume per dose
0.100 mL
Syringe units to draw
10 units
Total doses per vial
20 doses
Days supply
20 days
(2 weeks, 6 days)
Common reconstitution protocols
| Peptide | Vial | BAC Water | Typical Dose | Volume | |
|---|---|---|---|---|---|
| Retatrutide | 4 mg | 2 mL | 500 mcg | 0.25 mL (25 units) | |
| Semaglutide | 5 mg | 2 mL | 250 mcg | 0.1 mL (10 units) | |
| Tirzepatide | 10 mg | 2 mL | 2.5 mg | 0.5 mL (50 units) | |
| BPC-157 | 5 mg | 2 mL | 250 mcg | 0.1 mL (10 units) | |
| Ipamorelin | 5 mg | 2.5 mL | 200 mcg | 0.1 mL (10 units) | |
| TB-500 | 5 mg | 2 mL | 2.5 mg | 1.0 mL (100 units) | |
| CJC-1295 | 5 mg | 2.5 mL | 100 mcg | 0.05 mL (5 units) |
How peptide reconstitution works
Peptides come as a lyophilized (freeze-dried) powder in a vial. Before you can inject them, you need to add bacteriostatic water (BAC water) to dissolve the powder. This process is called reconstitution.
The amount of water you add determines the concentration. More water = weaker solution = more volume per dose. Less water = stronger solution = less volume per dose. The total amount of peptide stays the same.
Step-by-step reconstitution guide
- Clean the tops of both vials (peptide and BAC water) with alcohol swabs.
- Draw the desired amount of BAC water into a syringe.
- Insert the needle into the peptide vial at an angle. Let the water run down the side of the vial — do not squirt it directly onto the powder.
- Gently swirl the vial until the powder fully dissolves. Do not shake.
- Store reconstituted peptide in the refrigerator. Use within 30 days.
Tips for accurate reconstitution
- Use insulin syringes for drawing doses. They are more precise than standard syringes for small volumes.
- Never shake the vial. Peptides are fragile proteins. Shaking can damage them. Swirl gently.
- Refrigerate after reconstitution. Most reconstituted peptides are stable for 30 days refrigerated.
- Use bacteriostatic water, not sterile water. BAC water contains 0.9% benzyl alcohol as a preservative, allowing multi-dose use.
- Double-check your math. Or use this calculator. Dosing errors are the most common mistake beginners make.
FAQ
What is bacteriostatic water?
Bacteriostatic water is sterile water with 0.9% benzyl alcohol added as a preservative. The benzyl alcohol prevents bacterial growth, making it safe for multi-dose use over 28-30 days. It is the standard diluent for reconstituting peptides.
How long does reconstituted peptide last?
Most reconstituted peptides remain stable for 28-30 days when stored in the refrigerator at 2-8 degrees Celsius (36-46 degrees Fahrenheit). Some peptides like BPC-157 are more stable than others. When in doubt, reconstitute a fresh vial after 30 days.
Can I use more or less water than recommended?
Yes. The amount of water only changes the concentration, not the total peptide. Using less water means a smaller injection volume per dose. Using more water means a larger volume but can be easier to measure accurately. Common ranges are 1-3 mL per vial.
What if the powder does not dissolve?
Let the BAC water sit on the powder for a few minutes, then gently swirl. Some peptides take longer to dissolve. If particles remain after 10 minutes of gentle swirling, the peptide may have been damaged during shipping or storage. Do not inject solutions with visible particles.
Disclaimer: This calculator and information are for educational reference only. Always verify your calculations and consult with a healthcare provider before using any peptide. Errors in reconstitution can lead to incorrect dosing. See our full medical disclaimer.