Peptide Reconstitution Calculator

A peptide reconstitution calculator is a tool that helps you determine the exact volume to draw in your syringe for a specific peptide dose. You input the peptide vial size (in mg), the amount of bacteriostatic water you added (in ml), and your desired dose (in mcg), and the calculator tells you how many units to draw on your insulin syringe.

To calculate your peptide dose, use this three-step formula: (1) Divide the vial quantity in mg by the water volume in ml to get the concentration in mg/ml. (2) Divide your desired dose in mcg by the concentration × 1,000 to get the injection volume in ml. (3) Multiply the injection volume by the total syringe units divided by the syringe volume to convert to syringe units. For example, a 5mg vial reconstituted with 2ml of bacteriostatic water gives a 2.5 mg/ml concentration. A 250 mcg dose requires 0.1 ml, which equals 10 units on a 100-unit (1 ml) syringe.

The most common reconstitution volumes for a 5mg peptide vial are 1 ml or 2 ml of bacteriostatic water. Using 1 ml creates a 5 mg/ml concentration (more concentrated, smaller injection volume), while 2 ml creates a 2.5 mg/ml concentration (easier to measure smaller doses). Your prescribing clinician will recommend the appropriate volume based on your specific peptide and dosing protocol.

Milligrams (mg) and micrograms (mcg) are both units of weight. 1 mg equals 1,000 mcg. Peptide vials are typically labeled in milligrams (e.g., 5 mg, 10 mg), while individual doses are usually measured in micrograms (e.g., 250 mcg, 500 mcg). This is because each dose is a small fraction of the total vial contents.

Units on an insulin syringe refer to volume markings. A 100-unit syringe holds 1 ml total, so each unit equals 0.01 ml. A 50-unit syringe holds 0.5 ml (each unit = 0.01 ml), and a 30-unit syringe holds 0.3 ml (each unit = 0.01 ml). The "units" are not related to drug potency — they are simply volume markers that make it easier to measure small injection volumes accurately.

The number of doses per vial depends on the vial size and your dose amount. Divide the total vial quantity (in mcg) by your dose (in mcg). For example, a 5 mg vial (5,000 mcg) at 250 mcg per dose yields 20 doses. A 10 mg vial at 500 mcg per dose also yields 20 doses. Our calculator automatically shows your doses-per-vial count.

Sterile water for injection (SWFI) can be used but is not ideal for multi-dose vials. Bacteriostatic water contains 0.9% benzyl alcohol as a preservative, which inhibits bacterial growth and allows safe use over multiple injections for up to 28 days. Sterile water has no preservative, so it should only be used for single-dose applications. Always follow your healthcare provider's instructions.

Reconstituted peptides typically remain stable for 3-4 weeks when stored at 2-8°C (36-46°F) in a standard refrigerator. For longer storage, peptide solutions can be frozen at -20°C for 3-4 months. Avoid repeated freeze-thaw cycles. Unreconstituted lyophilized powder is far more stable and can be stored at -20°C for years.

Most peptide users use insulin syringes, which come in three common sizes: 0.3 ml (30 units), 0.5 ml (50 units), and 1.0 ml (100 units). For small doses, a 0.3 ml syringe provides the finest graduation marks and greatest accuracy. For larger doses, a 0.5 ml or 1.0 ml syringe may be necessary to hold the full injection volume. Use the smallest syringe that can accommodate your dose for the most accurate measurement.

Yes, our peptide reconstitution calculator is completely free to use with no signup or registration required. It works on all devices — desktop, tablet, and mobile. You can use it as many times as needed to calculate dosing for any injectable peptide.