Peptide reconstitution calculator
Convert any vial size, water volume, and target dose into an exact insulin-syringe unit reading — with a live syringe visual. Runs in your browser; nothing is stored.
Mixing two or more peptides in one vial? Use the blend & stack calculator (Wolverine, GLOW, CJC-1295 + Ipamorelin, and more).
How the math works
Reconstitution is just a concentration problem. When you add bacteriostatic water to a lyophilized (freeze-dried) vial, the peptide dissolves into that volume of liquid. The concentration is the total peptide divided by the water added:
Concentration (mcg/mL) = (vial mg × 1000) ÷ water mL. To get a target dose, you draw a volume equal to dose ÷ concentration. On a U-100 insulin syringe there are 100 units per millilitre, so the unit reading is simply that volume in millilitres × 100.
Example: a 5 mg vial reconstituted with 2 mL of water gives 2,500 mcg/mL. A 250 mcg target is 0.1 mL, which reads as 10 units on a U-100 syringe — and the vial holds 20 such doses.
This tool is for research calculations only. It does not recommend doses, and nothing here is medical advice.
Peptide calculator FAQ
What is a peptide reconstitution calculator?
It is a free tool that turns three inputs — the amount of peptide in your vial (mg), the volume of bacteriostatic water you add (mL), and your target dose (mcg) — into the exact number of insulin-syringe units to draw. It also shows the concentration and how many doses the vial holds. Everything runs in your browser and nothing is stored.
How much bacteriostatic water should I use for a peptide vial?
There is no single required amount — the water volume only sets the concentration, not how much peptide you have. A common, realistic choice is 2 mL of bacteriostatic water for a typical vial. For example, a 10 mg vial in 2 mL gives 5,000 mcg/mL (1 unit ≈ 50 mcg); a 5 mg vial in 2 mL gives 2,500 mcg/mL. Adding more water makes each unit carry less, which can make small doses easier to measure.
How do I convert mg to insulin units?
First find the concentration: mcg per mL = vial mg × 1000 ÷ water mL. On a U-100 insulin syringe there are 100 units per mL, so 1 unit = 0.01 mL. Units to draw = (target mcg ÷ concentration) × 100. The calculator does this for you and draws it on a live syringe.
How many units is a 250 mcg dose?
It depends on the concentration. At 2,500 mcg/mL (a 5 mg vial in 2 mL), 250 mcg is 0.1 mL = 10 units. At 5,000 mcg/mL (a 10 mg vial in 2 mL), 250 mcg is 0.05 mL = 5 units. Enter your own vial and water above to get the exact figure.
What is bacteriostatic water, and how is it different from sterile water?
Bacteriostatic water is sterile water containing about 0.9% benzyl alcohol, a preservative that suppresses microbial growth so a vial can be entered multiple times over a storage window (commonly cited as up to 28 days refrigerated). Plain sterile water has no preservative and is generally treated as single-use once opened.
How many doses will my vial last?
Divide the total peptide by your dose: doses per vial = (vial mg × 1000) ÷ dose mcg. A 10 mg vial dosed at 250 mcg holds 40 doses. The calculator shows this automatically as you type.