At a glance
| Mark on U-100, 1 mL | Volume | at 1 mg/mL | at 2 mg/mL | at 2.5 mg/mL | at 5 mg/mL | at 10 mg/mL |
|---|---|---|---|---|---|---|
| 5 units | 0.05 mL | 0.05 mg | 0.1 mg | 0.125 mg | 0.25 mg | 0.5 mg |
| 10 units | 0.1 mL | 0.1 mg | 0.2 mg | 0.25 mg | 0.5 mg | 1 mg |
| 20 units | 0.2 mL | 0.2 mg | 0.4 mg | 0.5 mg | 1 mg | 2 mg |
| 25 units | 0.25 mL | 0.25 mg | 0.5 mg | 0.625 mg | 1.25 mg | 2.5 mg |
| 40 units | 0.4 mL | 0.4 mg | 0.8 mg | 1 mg | 2 mg | 4 mg |
| 50 units | 0.5 mL | 0.5 mg | 1 mg | 1.25 mg | 2.5 mg | 5 mg |
| 100 units | 1 mL | 1 mg | 2 mg | 2.5 mg | 5 mg | 10 mg |
Arithmetic at the concentrations shown. The concentration on your own label is the one that counts; enter it in the calculator.
Why the milligrams depend on the pharmacy label
20 units is 0.2 mL. That is 0.2 mg at 1 mg/mL, 0.5 mg at 2.5 mg/mL, 1 mg at 5 mg/mL and 2 mg at 10 mg/mL. Two of those, 0.5 mg and 1 mg, are strengths on the Wegovy and Ozempic labels, which is why 20 units is such a common number in conversations about semaglutide vials: at 2.5 or 5 mg/mL it lands on a familiar dose. But a familiar number is not a check. At 10 mg/mL the same 20 units is 2 mg, four times the dose at 2.5 mg/mL. The concentration on your own pharmacy label decides which of these is yours. The reverse check is worth doing every time: multiply the mark by the concentration and compare the result with the milligrams on your prescription. Twenty units times 2.5 mg/mL is 0.5 mg; if your prescription says 1 mg, either the mark or the concentration you are assuming is wrong, and the syringe will not tell you which.
The mistake to watch for. If your label says 5 mg in 2 mL, the concentration is 2.5 mg/mL and 20 units is 0.5 mg. If it says 5 mg in 1 mL, it is 5 mg/mL and 20 units is 1 mg. The vial amount is the same in both; the volume changes everything.