How is BAC water different from sterile water?

Sterile water contains no preservatives and must be used immediately after opening. BAC water can be used for up to 28 days due to its benzyl alcohol preservative.

What concentration should I use?

Choose a concentration that results in easily measurable doses (10-50 insulin units). For most peptides, 2-3 mg/mL works well with standard 5mg vials.

How do I reconstitute peptides properly?

1) Wipe vial tops with alcohol. 2) Draw BAC water into syringe. 3) Inject slowly along the vial wall, not directly onto powder. 4) Swirl gently - never shake. 5) Wait for complete dissolution.

Peptides

Bacteriostatic Water Calculator

Calculate how much bacteriostatic water to add for your desired peptide concentration. Optimize reconstitution for easy dosing with insulin syringes.

BAC Water

Calculate how much bacteriostatic water to add for your desired peptide concentration. Optimize reconstitution for easy dosing with insulin syringes.

Peptide AmountTotal peptide content in your vial

Desired ConcentrationTarget concentration after reconstitution

mg/mL

Typical DoseYour expected dose per administration

mcg

For research purposes only. Always use proper sterile technique when reconstituting peptides.

Visual Syringe Guide

Use this interactive syringe visualization to verify your calculated dose. Enter the volume from your calculation above to see exactly where the plunger should land.

Syringe Configuration

Desired Volume (mL)

Quick Select

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

Administration Note

For a 0.50 mL dose, pull the plunger back until the top ring of the black stopper aligns with the corresponding mark.

Volume Match0.50 mL

Important Disclaimer

For research purposes only. Always use proper sterile technique when reconstituting peptides.

About This Calculator

Bacteriostatic water (BAC water) contains 0.9% benzyl alcohol as a preservative, allowing reconstituted peptides to remain stable for multiple uses over several weeks. This calculator helps you determine the optimal amount of BAC water to achieve your desired concentration.

How It Works

Enter your peptide vial size, desired concentration, and typical dose. The calculator determines how much BAC water to add and shows the resulting volume per dose in both mL and insulin syringe units.

Frequently Asked Questions

Bacteriostatic water is sterile water containing 0.9% benzyl alcohol. The preservative inhibits bacterial growth, allowing the vial to be used multiple times over 28 days when stored properly.

Clinical Review

Dr. Igor I. Bussel, MD

Board-Certified Ophthalmologist

Dr. Igor I. Bussel is a board-certified ophthalmologist and fellowship-trained surgeon affiliated with the University of California, Irvine (UCI), the Gavin Herbert Eye Institute, and the UCI School of Medicine.

Last Updated: 2026-01-06

Sources & Guidelines

USP <797> Pharmaceutical Compounding - Sterile Preparations.
CDC Guidelines for Safe Injection Practices.

Medically Reviewed

Evidence-Based

Updated 2026-01-06

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References

USP <797> Pharmaceutical Compounding - Sterile Preparations.
CDC Guidelines for Safe Injection Practices.

Last updated: 2026-01-06