The same weekly dose of tirzepatide is a different number of units on different vials, because units measure volume, not medicine. A 7.5mg dose is 45 units from a 16.6mg per ml vial but 42 units from a 17.65mg per ml vial. Always read the strength printed on your own vial before you draw up.
This article explains how the numbers work. It is not a dose recommendation. Your prescribing provider sets your dose.
Why is the number of units different from vial to vial?
Compounded tirzepatide is mixed at a different strength by each pharmacy, and sometimes by each kit. A more concentrated vial holds more medicine in each millilitre, so you need fewer units on the syringe for the same weekly dose.
Units are marks on an insulin syringe. On a standard 1ml syringe, 100 units is 1 millilitre. The syringe knows nothing about how strong your vial is. Only the label does.
What are the units for the vials we see most often?
These are the schedules our compounding pharmacies supply with their kits, in units on a 1ml syringe. Try it first, then use the table as a reference.
See the same dose on three different vials
Pick a weekly dose. The bars show how far you draw on a 1ml insulin syringe (100 units).
A 7.5mg weekly dose is 38 to 45 units, depending on the vial. Same dose, different volume.
These are the schedules the pharmacies supply with their kits, shown as examples. Your prescribing provider sets your dose.
| Weekly dose | Wells, tirzepatide with glycine, 16.6mg per ml | OptioRx, tirzepatide with niacinamide, 17.65mg per ml | ReViveRx 40mg kit, 10mg per 0.5ml |
|---|---|---|---|
| 2.5mg | 15 units | 14 units | 13 units |
| 5mg | 30 units | 28 units | 25 units |
| 7.5mg | 45 units | 42 units | 38 units |
| 10mg | 60 units | 57 units | 50 units |
| 12.5mg | 75 units | 71 units | 63 units |
| 15mg | 90 units | 85 units | 75 units |
The three columns are not interchangeable. A 16.6mg per ml vial and a 17.65mg per ml vial look the same and hold different amounts of medicine, so 45 units from the wrong one is not the dose you think it is.
How do I work out units from my own vial?
- Divide your weekly dose in mg by the mg per ml printed on the vial. That gives millilitres.
- Multiply by 100. That gives units on a 1ml insulin syringe.
For example, 7.5mg from a 16.6mg per ml vial is 0.45ml, which is 45 units. Every number in the table is this same sum, rounded to the nearest whole unit.
If you would rather not do the maths, our GLP-1 vial calculator does it for you. Type in what is printed on your label and your weekly dose, and it shows the units to draw, how many doses the vial holds and the working step by step.
Why is 2.5mg 15 units on one vial and 14 on another?
Because the two vials are mixed at different strengths. At 16.6mg per ml, 2.5mg is 0.151ml, which rounds to 15 units. At 17.65mg per ml, the same 2.5mg is 0.142ml, which rounds to 14 units. The dose is the same. The volume is not.
What do the glycine and niacinamide on my label mean?
They are carriers the compounding pharmacy adds to the formulation. The number that matters when you draw up is the tirzepatide strength, the first figure on the label, because the unit counts above are worked out from that.
How long can I use a vial once I start it?
The pharmacy notes supplied with these kits state that the FDA and USP require compounding pharmacies to recommend that multi-dose vials be used within 28 days unless the vial has been tested to last longer. For larger vials, go by the beyond-use date printed on the vial itself. If it is not clear, ask your provider.
Frequently asked questions
How many units is 5mg of tirzepatide?
It depends on the vial. On the three vials above it is 30, 28 or 25 units on a 1ml syringe. Check the strength on your label.
Is 10 units of tirzepatide always the same dose?
No. Units measure volume. The same 10 units holds a different amount of tirzepatide depending on how concentrated the vial is.
Can I use the chart for a vial from another pharmacy?
Only if the strength printed on your vial matches one of the columns. If it does not, use the formula above or the vial calculator, and ask your provider if you are unsure.
Does this tell me what dose to take?
No. These schedules are examples supplied by the pharmacies with their kits. Your prescribing provider sets your dose and steps it up only when needed.
How do I plan how many vials I need?
Use the quantity planner. Enter your weekly dose and it works out the total mg, the vial size that covers it and the monthly cost. You can see current prices on our tirzepatide pricing programs page.
More from this guide series
Next step
Questions about your own vial or plan? Start the free intake form and a provider will take you through it.