How to reconstitute a peptide
Reconstitution is the math of turning a dry peptide vial into a measured liquid dose. It comes down to three numbers you already have: the milligrams of peptide in the vial, the milliliters of bacteriostatic water you mix in, and the dose you're aiming for.
Divide the peptide amount by the water to get your concentration. Divide your dose by that concentration to get the volume to inject. Because insulin syringes are marked in units rather than milliliters, the last step converts that volume into units — on a U-100 syringe, one milliliter is 100 units. The calculator above does all three steps live, and the diagram shows where the fill line lands.
The amount of water you add is a choice, not a fixed rule. More water means a lower concentration and a larger, easier-to-read draw; less water means a smaller, more concentrated one. A good habit is to adjust the water until your target dose lands on a clean number of units.
Common questions
Divide the total peptide in the vial (mg) by the bacteriostatic water you add (mL) to get concentration in mg/mL. Divide your target dose by that concentration to get the volume to inject, then multiply by 100 to convert milliliters into units on a U-100 insulin syringe.
There's no single right amount. More water lowers the concentration so each dose is a larger, easier-to-measure volume; less water makes a smaller draw. Many people pick an amount that makes their target dose land on a round number of units. Try different values above and watch the units change.
It depends on concentration. A 10 mg vial mixed with 2 mL of water is 5 mg/mL, so 250 mcg works out to 0.05 mL — which is 5 units on a U-100 syringe. Change the vial size or water and the units shift, so always run your own numbers.
It's a syringe marked so that 100 units equals 1 milliliter — the standard for measuring small volumes. On a U-100 syringe, 10 units is 0.1 mL and 50 units is 0.5 mL.
One milligram equals 1000 micrograms. Vials are usually labeled in mg, while doses are often given in mcg. The calculator converts between them automatically based on the unit you pick.