At a glance
| Volume | U-100, 1 mL mark | U-100, 0.5 mL mark | U-40, 1 mL mark |
|---|---|---|---|
| 0.05 mL | 5 | 5 | 2 |
| 0.1 mL | 10 | 10 | 4 |
| 0.2 mL | 20 | 20 | 8 |
| 0.25 mL | 25 | 25 | 10 |
| 0.3 mL | 30 | 30 | 12 |
| 0.4 mL | 40 | 40 | 16 |
| 0.5 mL | 50 | 50 | 20 |
Arithmetic at the concentrations shown. The concentration on your own label is the one that counts; enter it in the calculator.
Why the marks mean volume
Half a millilitre is the most common volume on this site, because every Zepbound single-dose vial holds exactly that, and because one of the three insulin syringe sizes stops there. On the U-100 scale, 0.5 mL is 50 units: halfway up a 1 mL syringe, the top of a 0.5 mL syringe. On a U-40 syringe, made for veterinary insulins at 40 units per mL, the same 0.5 mL is the 20 mark. For U-100 insulin, 50 units of volume is 50 units of insulin, because the scale was designed for it. For any other medication, 0.5 mL holds whatever the concentration says: 2.5 mg at 5 mg/mL, 500 units of HCG at 1,000 units per mL. The table shows the marks for common volumes on all three syringes.
The mistake to watch for. A full 0.5 mL syringe and the 50 mark on a 1 mL syringe are the same volume. People switching between the two sizes sometimes read the top of the smaller syringe as "100" because it is the top. It is 50.