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Peptide Reconstitution Calculator — Reconstitute Any Peptide Correctly

Calculate concentration, injection volume, and syringe units for any peptide vial. Enter your vial size, BAC water amount, and desired dose below.

Peptide reconstitution is the process of dissolving a lyophilized (freeze-dried) peptide powder in bacteriostatic water to create an injectable solution. The amount of BAC water you add directly determines the concentration — and therefore the exact volume you inject per dose. The formula is the same one used by compounding pharmacies: Concentration (mcg/ml) = (Vial mg × 1000) ÷ BAC water ml.

Quick Answer

Standard reconstitution for a 5mg peptide vial: add 2ml of bacteriostatic water → concentration is exactly 2500 mcg/ml. A 250mcg dose = 0.10ml (10 units) on a 100-unit syringe. Enter your vial size and BAC water below to calculate any combination.

Common Reconstitution Reference

Common vial + BAC water combinations and their resulting concentrations.

Vial SizeBAC WaterConcentrationExample: 250mcg dose
2mg1ml2,000 mcg/ml0.125ml = 12.5 units
5mg1ml5,000 mcg/ml0.050ml = 5 units
5mg2ml2,500 mcg/ml0.100ml = 10 units
5mg3ml1,667 mcg/ml0.150ml = 15 units
10mg2ml5,000 mcg/ml0.050ml = 5 units
10mg4ml2,500 mcg/ml0.100ml = 10 units

How Peptide Reconstitution Works

Peptides are typically supplied as lyophilized (freeze-dried) powders to preserve stability during storage and shipping. Before use, they must be reconstituted — dissolved in bacteriostatic water to create an injectable solution.

The concentration of your reconstituted peptide determines how much liquid you inject per dose. A higher concentration means smaller injection volumes, which is generally more comfortable. A lower concentration means larger volumes, which can be easier to measure precisely with a standard insulin syringe.

The formula used by this calculator is the same one used by compounding pharmacies worldwide:

Concentration (mcg/ml) = (Vial size in mg × 1000) ÷ BAC water in ml Inject volume (ml) = Desired dose (mcg) ÷ Concentration (mcg/ml) Syringe units = Inject volume (ml) × 100

For example: a 5mg vial reconstituted with 2ml BAC water has a concentration of 2500 mcg/ml. A 250mcg dose requires 0.1ml — which is 10 units on a 100-unit insulin syringe.

Frequently Asked Questions

Peptide reconstitution is the process of dissolving a lyophilized (freeze-dried) peptide powder in bacteriostatic water (BAC water) to create an injectable solution. The amount of BAC water you add determines the concentration of the final solution.
The standard recommendation is 1–2ml of BAC water per 5mg vial. Using 2ml gives a concentration of 2500 mcg/ml, which means a typical 250mcg dose equals just 0.1ml (10 units on an insulin syringe).
The solution should be clear and colorless. Gently swirl the vial — do not shake vigorously as this can degrade the peptide. If the powder has fully dissolved with no visible particles, it is ready.
Bacteriostatic water is strongly preferred. BAC water contains 0.9% benzyl alcohol which acts as a preservative, allowing the solution to remain stable for 28–30 days when refrigerated. Plain sterile water should be used within 24 hours.
When reconstituted with bacteriostatic water and stored at 2–8°C (refrigerator temperature), most peptides remain stable for 28–30 days. Keep away from light and do not freeze the reconstituted solution.
BAC Water Calculator Calculate how much BAC water to add. mg to ml Calculator Convert milligrams to milliliters. Peptide Dosage Chart Reference for 25+ peptides. mcg to mg Calculator Convert micrograms to milligrams.