Drug facts
Tirzepatide dosage in units
Have a vial in front of you? Convert your dose here, or, if you are mixing from powder, start with the reconstitution calculator.
Quick answer
A unit is a mark on a U-100 syringe: 100 units is one milliliter of liquid. How much tirzepatide is in that liquid depends on your vial’s concentration. So 2.5 mg is 25 units from a 10 mg/mL vial, 50 units from a 5 mg/mL vial and 12.5 units from a 20 mg/mL vial. The chart below does the same sum for every dose on the label.
Why there are two different numbers at all1
Doses of tirzepatide are written in milligrams: 2.5 mg, 5 mg, 7.5 mg. That is a quantity of drug. A syringe cannot measure drug, only liquid. Insulin syringes, which compounded vials are usually drawn with, are marked in units, and on the standard U-100 syringe those marks divide one milliliter into a hundred parts.
So “units” answers how much liquid, and “milligrams” answers how much drug. The bridge between them is the concentration of your vial, in milligrams per milliliter: units = mg ÷ mg/mL × 100.
Tirzepatide mg to units chart, by vial strength2
The rows are the doses in the Zepbound label, which starts at 2.5 mg a week and steps up by 2.5 mg to a maximum of 15 mg. The columns are example vial strengths. Find your prescribed dose and your vial’s mg/mL, and the cell is the mark on the syringe.
| Dose | 5 mg/mL | 10 mg/mL | 15 mg/mL | 20 mg/mL |
|---|---|---|---|---|
| 2.5 mg | 50 units | 25 units | 16.7 units | 12.5 units |
| 5 mg | 100 units | 50 units | 33.3 units | 25 units |
| 7.5 mg | over 1 mL | 75 units | 50 units | 37.5 units |
| 10 mg | over 1 mL | 100 units | 66.7 units | 50 units |
| 12.5 mg | over 1 mL | over 1 mL | 83.3 units | 62.5 units |
| 15 mg | over 1 mL | over 1 mL | 100 units | 75 units |
Two patterns are worth noticing. On a weak vial the upper doses stop fitting in a 1 mL syringe. On a strong one the low doses shrink to a handful of lines, where a one-line misread is a real share of the dose. The approved multi-dose vial avoids both by changing strength with the dose, from 4.17 mg/mL for 2.5 mg to 25 mg/mL for 15 mg, so every dose is the same 0.6 mL, or 60 units.1
How many units is 2.5 mg of tirzepatide?
Read the first row of the chart: 50 units at 5 mg/mL, 25 at 10 mg/mL, about 16.7 at 15 mg/mL, 12.5 at 20 mg/mL. The same starting dose is four different marks on four different vials, and none of them is wrong. What would be wrong is carrying a mark from one vial to the next. The same goes for 5 mg (100, 50, about 33, and 25 units) and every step above it.
Why the same dose is a different number of units at different pharmacies3
Compounded vials are not standardized. One pharmacy may supply a concentration that puts your dose near the middle of the syringe; another, a stronger vial where the identical milligram dose is a much smaller mark. Neither is wrong, but they are not interchangeable, and it matters most at the moment you change supplier. What changes when you switch covers that.
On the label — Mounjaro / Zepbound
Supplied in single-dose pens and vials at a fixed strength, or a multi-dose vial built so each dose is 0.6 mL. There is no concentration for you to work out.
In a compounded vial
Concentration is chosen by the compounding pharmacy and printed on the vial. Two vials with the same total milligrams can hold different concentrations, so the mark on the syringe does not transfer between them.
How much bacteriostatic water for a 10 mg or 30 mg vial?5
If your vial arrives as a powder, the volume of water decides its concentration, and so every mark on this page. That volume should come from the pharmacy that dispensed it or from your prescriber. The table shows what each choice produces; the reconstitution calculator does it for any vial and carries the result to the units tool.
| Vial | + 1 mL | + 2 mL | + 3 mL |
|---|---|---|---|
| 10 mg | 10 mg/mL | 5 mg/mL | 3.33 mg/mL |
| 20 mg | 20 mg/mL | 10 mg/mL | 6.67 mg/mL |
| 30 mg | 30 mg/mL | 15 mg/mL | 10 mg/mL |
A powder sold “for research use only” is another matter. FDA says tirzepatide sold that way is sold illegally and is of unknown quality, and no approved tirzepatide is a powder. What FDA has said about research vials.
What to check on your own vial4
Your label should give the concentration in milligrams per milliliter, the total amount in the vial, and a beyond-use date. With those three, your prescriber’s instructions become a mark you can find on the syringe. If any is missing, raise it with the pharmacy before the first dose. The beyond-use date is explained under storage and expiry, and what the starting and maintenance doses are under the dosage chart.
How many units to draw, whether to change a dose and what to do about a missed one depend on your vial and your history, and belong to the prescriber and pharmacy who supplied them.
Questions
- How many units is 2.5 mg of tirzepatide?
- On a U-100 syringe: 50 units at 5 mg/mL, 25 units at 10 mg/mL, about 16.7 units at 15 mg/mL and 12.5 units at 20 mg/mL. On the approved multi-dose vial, which is 4.17 mg/mL, it is 60 units. Use the concentration printed on your own vial.
- How many units is 5 mg of tirzepatide?
- 100 units (a full 1 mL syringe) at 5 mg/mL, 50 units at 10 mg/mL, about 33.3 units at 15 mg/mL and 25 units at 20 mg/mL.
- How many units is 7.5 mg of tirzepatide?
- 75 units at 10 mg/mL, 50 units at 15 mg/mL and 37.5 units at 20 mg/mL. At 5 mg/mL it is 1.5 mL, more than a 1 mL syringe holds.
- What is the tirzepatide dosage in units for weight loss?
- There isn't one number. The label sets tirzepatide doses in milligrams, starting at 2.5 mg once weekly and rising in 2.5 mg steps to 5 to 15 mg. How many units any of those is depends on the concentration of the vial you were dispensed. Your prescriber sets the dose; the chart on this page converts it.
- How many units is 10 mg of tirzepatide?
- 100 units, a full 1 mL syringe, at 10 mg/mL; about 66.7 units at 15 mg/mL; 50 units at 20 mg/mL. At 5 mg/mL it is 2 mL and will not fit in one syringe.
Sources
- U-100 syringe convention; FDA prescribing information for ZEPBOUND, section 3, revision 8/2026 DailyMed
- FDA prescribing information for ZEPBOUND (tirzepatide), sections 2.1–2.2, revision 8/2026 DailyMed
- U-100 syringe convention; concentrations as published by compounding sellers
- General labeling practice for compounded preparations
- FDA, 'FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss', content current as of 09/01/2026 FDA