Peptide Reconstitution Calculator
Reconstituting a peptide? Enter your vial amount, your target dose, and how much bacteriostatic water you're adding — this free peptide reconstitution calculator tells you the exact number of units to draw on a U-100 or U-40 insulin syringe, plus your concentration and how many doses the vial holds.
100 units per mL — pick the syringe you have.
Draw to
BAC water
on a U-100 insulin syringe
Drag the syringe to set your dose, or type the values above.
Enter your vial amount and dose, then type the bacteriostatic water or drag the syringe to see the exact units to draw.
Never do this math twice.
The Pep AI app remembers your vials and doses, shows an interactive syringe you draw to, counts down the doses left in each vial, and reminds you when it's time. Free on iOS and Android.
How peptide reconstitution works
Reconstitution is the step of turning a dry (lyophilized) peptide into an injectable liquid by adding bacteriostatic water. The calculator does three pieces of math for you:
1. Concentration
Vial amount ÷ water added. A 5 mg vial with 2 mL of water is 2.5 mg/mL.
2. Volume per dose
Your dose ÷ concentration. A 0.25 mg dose at 2.5 mg/mL is 0.1 mL.
3. Units to draw
Volume per dose × 100 for a U-100 syringe (or × 40 for a U-40). 0.1 mL on a U-100 syringe is 10 units.
Worked example
You have a 5 mg vial, you want a 250 mcg dose, and you add 2 mL of bacteriostatic water. Concentration is 5 ÷ 2 = 2.5 mg/mL. Volume per dose is 0.25 ÷ 2.5 = 0.1 mL. On a U-100 syringe that's 0.1 × 100 = 10 units, and the vial holds 20 doses.
Frequently asked questions
This calculator is provided for informational and educational purposes only and is not medical advice. Always confirm dosing with a qualified healthcare professional and double-check your own measurements before administering anything.