Peptide Vial Calculator — Doses Per Vial
How many doses a vial holds is vial amount divided by dose — but the number that actually matters is whether the vial runs out before its usable life does. Enter your vial size, water volume and dose to see both sides of that.
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.
Vial sizes and water volumes are shown for convenience — the dose field is deliberately not prefilled and has no suggestions. Enter your own numbers.
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.
Doses per vial, and why it is only half the answer
The arithmetic is simple. The example uses an arbitrary dose to show it:
1. Concentration
Vial amount ÷ water added. A 10 mg vial with 2 mL of water is 5 mg/mL.
2. Volume per dose
Your dose ÷ concentration. A 1 mg dose at 5 mg/mL is 0.2 mL.
3. Units to draw
Volume per dose × 100 for a U-100 syringe (or × 40 for a U-40). 0.2 mL on a U-100 syringe is 20 units.
Worked example
You have a 10 mg vial, you want a 1 mg dose, and you add 2 mL of bacteriostatic water. Concentration is 10 ÷ 2 = 5 mg/mL. Volume per dose is 1 ÷ 5 = 0.2 mL. On a U-100 syringe that's 0.2 × 100 = 20 units, and the vial holds 10 doses.
Two clocks, and the shorter one wins
A reconstituted vial has a finite usable life for two independent reasons. Chemically, peptides degrade in solution — cold slows it substantially but does not stop it, so potency drifts from the moment water goes in. Microbiologically, the preservative in bacteriostatic water has a finite protective capacity that is consumed by repeated entries.
Neither clock cares how much solution is left. A vial with plenty remaining can be past its window; a vial well inside its window can be empty. Which one binds depends on your interval — a daily protocol tends to empty the vial first, a weekly one tends to run past the window.
The doses-per-vial figure above, set against how often you use it, tells you which situation you are in. That is worth knowing before you reconstitute, because a vial you will only half-use is a vial to reconstitute at a different concentration or not at all.
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.
Built by the Pep AI team.