Peptide Reconstitution Calculator
Enter your vial strength, how much bacteriostatic water you added, and your target dose. You'll get the exact draw volume, insulin-syringe units, solution concentration and how many doses the vial holds.
The formula
Concentration (mg/mL) = vial strength (mg) ÷ bacteriostatic water (mL). Draw volume (mL) = dose (mg) ÷ concentration (mg/mL). On a U-100 insulin syringe, units = draw volume (mL) × 100. Example: a 10 mg vial mixed with 2 mL of water is 5 mg/mL, so a 250 mcg dose is 0.05 mL — 5 units.
Your vial
1 mg = 1,000 mcg
Your result
Draw to
5
units on a U-100 insulin syringe
= 0.05 mL
- Concentration
- 5mg/mL
- 5,000 mcg/mL
- Doses per vial
- 40
- at 250 mcg each
For laboratory and research use only. This calculator is a unit-conversion aid and is not medical guidance or a dosing recommendation.
Shop USA-made research peptidesQuick reference: units per dose by vial size
Units shown are for a U-100 insulin syringe with the vial reconstituted in 2 mL of bacteriostatic water.
| Vial | Concentration | 250 mcg | 500 mcg | 1 mg | 2.5 mg |
|---|---|---|---|---|---|
| 2 mg | 1 mg/mL | 25 u | 50 u | 100 u | 250 u |
| 5 mg | 2.5 mg/mL | 10 u | 20 u | 40 u | 100 u |
| 10 mg | 5 mg/mL | 5 u | 10 u | 20 u | 50 u |
| 15 mg | 7.5 mg/mL | 3.3 u | 6.7 u | 13.3 u | 33.3 u |
| 20 mg | 10 mg/mL | 2.5 u | 5 u | 10 u | 25 u |
| 30 mg | 15 mg/mL | 1.7 u | 3.3 u | 6.7 u | 16.7 u |
How to reconstitute a lyophilised peptide vial
- 1. Bring the vial to room temperature. Let a refrigerated or frozen vial equilibrate before opening so condensation doesn't form on the powder.
- 2. Swab both stoppers. Wipe the peptide vial and the bacteriostatic water vial with alcohol and let them dry.
- 3. Draw your diluent. Pull the volume you entered above into the syringe.
- 4. Run it down the glass wall. Angle the needle so the water flows down the side of the vial rather than jetting directly onto the peptide cake — shear and foaming degrade peptides.
- 5. Swirl, never shake. Roll the vial gently until fully clear. Do not vortex or shake.
- 6. Label and refrigerate. Mark the date and concentration, then store at 2-8 °C away from light.
Peptide calculator FAQs
How do you calculate peptide reconstitution?
Divide the vial strength by the volume of bacteriostatic water added to get the concentration. Concentration (mg/mL) = vial strength (mg) ÷ BAC water (mL). To find the draw volume for a target dose, divide the dose by that concentration. On a U-100 insulin syringe, 1.0 mL equals 100 units, so units = draw volume in mL × 100.
How many units is 250 mcg if I mix a 5 mg vial with 2 mL of water?
The concentration is 5 mg ÷ 2 mL = 2.5 mg/mL, or 2,500 mcg/mL. A 250 mcg dose is 0.1 mL, which is 10 units on a U-100 insulin syringe. That vial contains 20 doses.
Does the amount of bacteriostatic water change the total peptide?
No. The vial contains a fixed mass of lyophilised peptide. Adding more water only dilutes it, so each unit on the syringe carries less peptide and the draw volume for the same dose gets larger. More water can make small doses easier to measure accurately.
How long is a reconstituted peptide stable?
Once reconstituted with bacteriostatic water, most research peptides are stored refrigerated at 2-8 °C and are generally handled within about 3-4 weeks, protected from light and freeze-thaw cycles. Unreconstituted lyophilised vials are far more stable and are typically kept frozen for long-term storage.
What is bacteriostatic water?
Bacteriostatic water is sterile water containing 0.9% benzyl alcohol, which inhibits bacterial growth and allows a vial to be entered multiple times. Sterile water without a preservative is single-use only.