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Peptide reconstitution calculator
Work out the concentration of a reconstituted vial and the exact volume on a U-100 insulin syringe for any target quantity. Enter your vial size, the volume of bacteriostatic water you're adding, and the amount you need per draw.
How to reconstitute a peptide
Bring the vial to room temperature
Cold glass attracts condensation, and condensation makes the powder clump. Give it ten minutes out of the fridge.
Swab both stoppers
Wipe the rubber stopper on the peptide vial and the water vial with an alcohol swab and let them air dry.
Draw your water
Draw the volume of bacteriostatic water you decided on above into a U-100 syringe.
Add it slowly down the wall
Angle the needle so the water runs down the inside of the glass. Never fire it straight onto the powder.
Swirl, never shake
Roll the vial gently between your fingers, or just leave it to stand. Shaking shears the peptide and creates foam.
Label and refrigerate
Write the concentration and the date on the vial. Store at 2\u20138 \u00b0C, upright, away from light.
Calculator FAQs
How much bacteriostatic water should I add?
There is no single correct answer \u2014 the water volume only sets how concentrated the solution is. More water means larger, easier-to-measure draws but a weaker solution; less water means the opposite. Most people land between 1ml and 2ml because that keeps a typical draw in a comfortable part of the syringe scale.
What does a U-100 syringe unit actually mean?
U-100 means the syringe is graduated so that 100 units equals exactly 1 millilitre. So 10 units is 0.1ml, and 50 units is 0.5ml. The units marking is a volume scale, not a quantity of peptide \u2014 how much peptide those units contain depends entirely on your concentration.
Why does the calculator warn me above 100 units?
A standard 1ml U-100 syringe only holds 100 units. If your target quantity needs more than that, you physically cannot draw it in one go. Add more bacteriostatic water to make the solution more concentrated per unit \u2014 or split it across two draws.
What is the difference between the syringe and pen modes?
The maths is identical; only the language changes. Syringe mode shows the mark to draw to on a U-100 insulin syringe plus the equivalent volume in millilitres. Pen mode drops the syringe terminology and shows the same figure as clicks, since a dosing pen is dialled rather than drawn.
How many draws will one vial give me?
Divide the total quantity in the vial by your target per draw. The calculator shows this figure, rounded down \u2014 so a 10mg vial at 250mcg per draw gives 40. Bear in mind a small amount is always left behind in the vial and the needle.