Semaglutide reconstitution calculator

A 5 mg semaglutide vial is the most common research size, and 2 mL of bacteriostatic water is the cleanest match. That gives you 2.5 mg/mL, which puts a 0.25 mg starter dose at exactly 10 units. Easy to see, easy to draw, easy to repeat each Sunday.

In the worked example below, a 5 mg vial of Semaglutide reconstituted with 2 mL of BAC water produces a concentration of 2.5 mg/mL. To draw the example dose of 0.25 mg from that vial you pull 0.10 mL — about 10 units on a standard insulin syringe. Change any input and the rest updates instantly so you can pre-plan a vial before you ever touch a needle.

Vial size, diluent volume, and dose are the three inputs that genuinely change the answer. Doses-per-vial is a derived output — it's the vial mg divided by the dose mg, rounded down. The most common edge case is a tiny dose: at very high concentration, a 0.1 mL draw is only a few units on the syringe, which is hard to read accurately. If your unit count drops below five, consider reconstituting the next vial with more BAC water so each dose covers a larger volume.

Semaglutide vials commonly arrive at 2 mg, 5 mg, or 10 mg. The illustrative example on this page assumes a 5 mg vial reconstituted with 2 mL of bacteriostatic water, producing a concentration of 2.5 mg per mL. A 0.25 mg dose on that vial is 0.1 mL — exactly 10 units on a U-100 insulin syringe.

Because typical semaglutide doses are small relative to the vial, choosing a sensible diluent volume matters. Using 1 mL of BAC water on a 5 mg vial concentrates the solution and makes each draw a tiny number of units, which is harder to read accurately on the syringe. Using 3 mL spreads the dose over a larger volume and produces cleaner unit counts at the cost of slightly fewer total doses per vial.

A frequent point of confusion during a titration schedule is the relationship between dose mass (mcg), solution volume (mL), and syringe units. The concentration of the reconstituted vial is constant; for example, a 5 mg vial reconstituted with 2 mL results in a fixed concentration of 2,500 mcg/mL. However, the dose in mass changes with each titration step. A 0.25 mg illustrative dose is 250 mcg, which corresponds to a volume of 0.1 mL or 10 units on a U-100 syringe. When the schedule steps up to a 0.5 mg dose (500 mcg), the volume drawn must double to 0.2 mL or 20 units, even though the vial’s concentration has not changed. Accurately calculating the new volume for each dose increase is a crucial step for adhering to a planned schedule.