How to Reconstitute Peptides
A step-by-step guide to mixing lyophilized peptides with bacteriostatic water. This is educational information for research purposes — it does not replace instructions from a licensed professional or product documentation.
Step-by-step reconstitution
- 1
Gather your supplies
You will need the peptide vial, bacteriostatic water (BAC water), an alcohol swab, and a syringe. Confirm the vial size printed on your label before proceeding.
- 2
Let the peptide reach room temperature
If the peptide was refrigerated or frozen, let it warm to room temperature before adding liquid. Sudden temperature changes can affect stability.
- 3
Calculate the BAC water volume
Use the calculator below to determine how much bacteriostatic water to add based on your vial size and the concentration you need. A whole-mL volume is easier to measure accurately.
- 4
Draw and inject the BAC water
Clean the vial stopper with an alcohol swab. Draw the calculated amount of BAC water into a syringe, insert the needle into the vial, and inject slowly against the side wall — never directly onto the powder.
- 5
Gently swirl to dissolve
Roll or gently swirl the vial until the powder fully dissolves. Do not shake vigorously, as this can damage the peptide structure.
- 6
Label and store properly
Write the concentration (mg/mL), date mixed, and discard date on the vial. Store reconstituted peptides refrigerated at 2–8°C unless your product documentation specifies otherwise.
Calculate your dilution
Use our free calculator to find a practical BAC water volume and convert your target amount to U-100 syringe units. The calculator performs arithmetic — it does not choose an amount or schedule.
Questions about reconstitution
What is bacteriostatic water?
Bacteriostatic water (BAC water) is sterile water containing 0.9% benzyl alcohol, which inhibits bacterial growth. It is the standard diluent for reconstituting injectable peptides because it extends shelf life compared to sterile water alone.
How much water should I add to my peptide vial?
The amount depends on your vial size and the concentration you need. Use a peptide reconstitution calculator to find a practical volume that produces readable U-100 syringe units. There is no universal answer — it depends on your specific product and instructions.
Can I use sterile water instead of BAC water?
Sterile water can be used for single-use applications, but reconstituted peptides stored with sterile water must be used immediately or discarded. BAC water is preferred for multi-dose vials because the benzyl alcohol prevents bacterial contamination.
How long does reconstituted peptide last?
Storage life varies by compound, handling, and supplier instructions. Most reconstituted peptides stored refrigerated with BAC water remain stable for weeks, but always follow the product documentation and consult a qualified professional for your situation.
What does U-100 mean on a syringe?
U-100 refers to a syringe scale where 100 units equals 1 mL. This is the standard insulin syringe scale used for peptide injections. Make sure your syringe uses this scale before applying any calculator result.
Why inject against the vial wall?
Injecting BAC water slowly against the vial wall allows gentle mixing without direct impact on the lyophilized powder. This helps preserve the peptide structure and reduces the risk of foam formation.
Related guides and tools
Educational disclaimer
This guide is for research and educational purposes only. It does not diagnose, treat, prescribe, or replace guidance from a licensed professional. Always follow the instructions provided with your product and consult a qualified professional before handling any injectable compound. The Peptide App does not sell peptides and provides arithmetic conversion tools — not dosing recommendations.