Peptide Reconstitution Calculator

• Spraying water directly onto the powder. Always aim the stream of bacteriostatic water down the inside wall of the vial, letting it flow gently over the lyophilized cake. Spraying directly onto the powder can denature fragile peptide bonds.
• Using sterile water instead of bacteriostatic water for multi-use vials. Sterile water for injection (SWFI) contains no preservative and should only be used for single-dose applications. Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits microbial growth across multiple draws over 28 days.
• Shaking the vial to dissolve the peptide. Vigorous shaking introduces air bubbles and can denature the peptide through mechanical stress. Instead, gently swirl or roll the vial between your palms until the solution is clear.
• Forgetting to swab the vial stopper. Always wipe both the peptide vial and BAC water vial with a 70% isopropyl alcohol swab before piercing. This simple step prevents contamination that could degrade the peptide or cause infection.
• Not labeling the reconstituted vial. After mixing, write the peptide name, concentration (mcg per unit or per mL), date of reconstitution, and discard date on the vial. Unlabeled vials lead to dosing errors.
• Using the wrong syringe scale. Insulin syringes come in U-100 (100 units/mL) and U-40 (40 units/mL) formats. Most peptide dosing references assume U-100 syringes. Using U-40 syringes without adjusting the math will result in a 2.5x overdose.

For a complete walkthrough with photos and step-by-step instructions, see our How to Reconstitute Peptides guide. If you need help figuring out how much bacteriostatic water to purchase, the BAC Water Calculator can help you plan ahead. For compound-specific dosage ranges, check the Dosage Calculator.