Units = dose in mg ÷ vial mg/mL × 100
On a U-100 insulin syringe, 100 units is 1 mL. So 0.5 mg of semaglutide from a 2.5 mg/mL vial is 20 units (0.2 mL). Enter your label and your prescribed dose for your units, how many doses the vial holds and when it runs out.
Calculator · same formula as the dose-to-units calculator FDA alert read Oct 25, 2026 Nothing you enter leaves this page
Use the dose your prescriber wrote. This tool does arithmetic on it; it never suggests a dose. Compounded semaglutide and tirzepatide are not FDA-approved. Not medical advice; if the units on your label do not match, call your pharmacy before injecting.
Your vial
Paste your label or type the strength and size. Open a row for the arithmetic.
Vial units calculator
Nothing you type leaves this page.
Use the dose your prescriber wrote. This tool does arithmetic on it; it never suggests a dose.
Enter the strength (mg/mL), the vial size (mL), the dose your prescriber wrote (mg) to see the units.
Worked examples
The doses are the steps on the FDA-approved Wegovy and Zepbound labels. Yours is the one your prescriber wrote.
mg to units
| Dose | Units | mL |
|---|---|---|
| 0.25 mg | 10 | 0.1 |
| 0.5 mg | 20 | 0.2 |
| 1 mg | 40 | 0.4 |
| 1.7 mg | 68 | 0.68 |
| 2.4 mg | 96 | 0.96 |
| Dose | Units | mL |
|---|---|---|
| 2.5 mg | 25 | 0.25 |
| 5 mg | 50 | 0.5 |
| 7.5 mg | 75 | 0.75 |
| 10 mg | 100 | 1 |
| 12.5 mg | 125 | 1.25 |
| 15 mg | 150 | 1.5 |
At 10 mg/mL, 12.5 mg and 15 mg are more than one 1 mL syringe holds.
| Vial strength | Units |
|---|---|
| 2.5 mg/mL | 100 |
| 5 mg/mL | 50 |
| 10 mg/mL | 25 |
| 20 mg/mL | 12.5 |
Every strength from 2.5 to 20 mg/mL is on the compounded GLP-1 dosage chart in units.
What the FDA has seen go wrong
Its alert on compounded semaglutide dosing errors, in its own words.
FDA alert
FDA has received reports of adverse events, some requiring hospitalization, that may be related to overdoses due to dosing errors associated with compounded semaglutide injectable products. Dosing errors have resulted from patients measuring and self-administering incorrect doses of the drug and health care providers miscalculating doses of the drug.
In several reports, patients were instructed to use a U-100 (1 milliliter) insulin syringe to draw small doses, such as a 5-unit (0.05 milliliter) dose, from a multiple-dose vial.
FDA encourages patients to talk with their health care provider or compounder about how to measure and administer the intended dose of compounded semaglutide.
FDA: FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products · Content current as of 07/26/2024 · read Oct 25, 2026
Questions
Questions
4 answersHow many units is 0.5 mg of semaglutide at 2.5 mg/mL?
20 units on a U-100 insulin syringe (0.2 mL): 0.5 mg ÷ 2.5 mg/mL × 100. Check it against the units on your pharmacy label.
How many units is 2.5 mg of tirzepatide?
It depends on the vial strength. On a U-100 syringe, 2.5 mg is 100 units from a 2.5 mg/mL vial, 50 units from a 5 mg/mL vial, 25 units from a 10 mg/mL vial, 12.5 units from a 20 mg/mL vial.
How do I convert mg to units for a GLP-1 vial?
Divide the dose in mg by the vial strength in mg/mL, then multiply by 100. That is the mark on a U-100 insulin syringe, where 100 units is 1 mL.
How long will my vial last?
Multiply the strength by the vial size for the mg in the vial, then divide by your dose. A 2 mL vial at 2.5 mg/mL holds 5 mg: 10 doses of 0.5 mg, or 10 weeks at once a week, if every drop can be drawn. Your label’s discard date may come first.