At a glance
| Concentration | 0.5 mg is | Mark on U-100, 1 mL |
|---|---|---|
| 1 mg/mL | 0.5 mL | 50 |
| 2 mg/mL | 0.25 mL | 25 |
| 2.5 mg/mL | 0.2 mL | 20 |
| 5 mg/mL | 0.1 mL | 10 |
| 10 mg/mL | 0.05 mL | 5 |
Arithmetic at the concentrations shown. The concentration on your own label is the one that counts; enter it in the calculator.
Why the answer depends on the pharmacy label
0.5 mg is the second Wegovy and Ozempic strength. From a vial it is 50 units at 1 mg/mL, 25 units at 2 mg/mL, 20 units at 2.5 mg/mL, 10 units at 5 mg/mL and 5 units at 10 mg/mL. The spread matters because the number a pharmacy or a forum gives you in units is only correct for one of those concentrations. Two people both told "20 units" for 0.5 mg are only both right if both have 2.5 mg/mL vials. The pens the FDA approved carry no concentration you can borrow; the pen measures the dose internally. So for a vial, the mg/mL on the pharmacy label is the only bridge between the 0.5 mg on your prescription and the mark on your syringe, and the calculator will not fill it in for you.
The mistake to watch for. "0.5" on a prescription is milligrams. "0.5" on a syringe barrel is millilitres, 50 units. Confusing the two is a ten-fold error at 1 mg/mL and larger at higher concentrations.