Why this page has no presets
Every other medication page on this site starts from an FDA label that states a concentration. Semaglutide has no such label for a vial. The approved products deliver a measured dose through a pen, and the numbers printed on those pens tell you nothing about what is in a compounded vial. There is no vial to tap on this page. Type the mg/mL from your pharmacy label and the calculator turns it into a mark on your syringe, with the working shown.
Check the official label
Every number this page uses was read from these documents on 2026-09-04. The label is the authority; if it disagrees with this page, the label wins.
What exists, and what does not
From the Ozempic and Wegovy labels. Their listed strengths, quoted for comparison only: Wegovy 0.25, 0.5, 1, 1.7 and 2.4 mg once weekly; Ozempic 0.25, 0.5, 1 and 2 mg. Those describe pens. They do not carry over to a vial.
The trap with compounded vials
Comparing marks instead of milligrams. "I take 40 units" means 0.4 mL and nothing more. At 1 mg/mL that is 0.4 mg; at 5 mg/mL it is 2 mg. Two people saying the same number can be taking doses five times apart because their pharmacies chose different concentrations.
So the question for your pharmacy is not "how many units" but "what is the concentration of this vial in mg/mL, and what dose in mg did my prescriber write?" With those two numbers the mark follows, and you can check it: milligrams divided by mg/mL gives millilitres, and millilitres times 100 gives the mark on a U-100 syringe.
Reading a compounded label
If the label gives an amount and a volume instead of mg/mL, for example 5 mg in 2 mL, divide first: 2.5 mg/mL. If it gives only an amount, the pharmacy has to tell you the volume; the calculator cannot guess it.
Worked answers
Other questions
How much bacteriostatic water do I mix with semaglutide?
For the approved products, none; they are pens. For a compounded powder, the volume the pharmacy told you to add is the right one, because their instructions assume the concentration it produces. Enter it in the powder option and compare the concentration the calculator shows with what the pharmacy wrote.
Which syringe should I choose?
The one you were given, usually a U-100 insulin syringe in the 1 mL, 0.5 mL or 0.3 mL size. All three share one scale and differ only in how far it goes. If your dose does not fit the syringe, the calculator says so and names the sizes that would.
Can I draw from an Ozempic or Wegovy pen with a syringe?
The pens deliver a measured dose through their own needle. Withdrawing from one is not on the label and is not something this calculator models.