Short answer: it depends on your vial. At 2.5 mg/mL, 0.25 mg is 10 units on a U-100 insulin syringe. At 5 mg/mL, the same dose is 5 units.
That’s why “units” alone can be dangerous. The FDA has received reports of patients overdosing on compounded semaglutide, often because of confusion between units, milliliters, and milligrams.
The formula
Units = (dose in mg ÷ concentration in mg/mL) × 100
A U-100 insulin syringe holds 100 units per 1 mL, so multiplying mL by 100 gives you units.
Chart for common vial strengths
| Dose | 2.5 mg/mL | 5 mg/mL |
|---|---|---|
| 0.25 mg | 10 units | 5 units |
| 0.5 mg | 20 units | 10 units |
| 1 mg | 40 units | 20 units |
| 1.7 mg | 68 units | 34 units |
| 2.4 mg | 96 units | 48 units |
Your vial may use a different strength. Use the semaglutide units-to-mg calculator with the concentration printed on your label.
Three checks before every dose
- Read the concentration on the label, in mg/mL. Don’t assume it matches a previous vial or a friend’s.
- Confirm the syringe is U-100. Most insulin syringes are, and the barrel is marked in units.
- Match it to your prescriber’s instructions. If the pharmacy’s directions list units, follow them, and ask the pharmacist if they don’t match what you calculated.
Brand-name pens are different
Wegovy and Ozempic pens deliver fixed doses in mg, so you don’t count units. This chart is only for vials drawn up with a syringe.