Tirzepatide doses on the FDA labels
Zepbound (weight reduction, obstructive sleep apnea) and Mounjaro (type 2 diabetes) are tirzepatide, injected under the skin once a week. Both labels start at 2.5 mg and go up in 2.5 mg steps, each after at least 4 weeks on the current dose.
| Step | Dose | Label |
|---|---|---|
| Start, weeks 1 to 4; for starting only, not a maintenance dose | 2.5 mg | Zepbound, |
| From week 5 | 5 mg | Zepbound, |
| Each step up, after at least 4 weeks on the current dose | +2.5 mg | Zepbound, |
| Maintenance, weight reduction | 5, 10 or 15 mg | Zepbound, |
| Maintenance, obstructive sleep apnea | 10 or 15 mg | Zepbound, |
| Maximum | 15 mg | Zepbound, |
| Start | 2.5 mg | Mounjaro, |
| Each step up, if more glucose control is needed, after at least 4 weeks on the current dose | +2.5 mg | Mounjaro, |
| Maximum, adults | 15 mg | Mounjaro, |
| Maximum, children 10 years and older | 10 mg | Mounjaro, |
Each strength comes as a single-dose pen or vial with one dose in 0.5 mL, and as a multi-dose vial or KwikPen with four doses of 0.6 mL: 10 mg in 2.4 mL for 2.5 mg doses, up to 60 mg in 2.4 mL for 15 mg doses. For the vials, the labels ask for a 1 mL syringe that can measure 0.5 or 0.6 mL: the 50 and 60 unit lines on a U-100 syringe.
Each label dose in units
A tirzepatide vial mixed or filled at another strength gives the same dose in a different number of units. The table shows the units on a U-100 syringe at three strengths; the calculator above works out any other.
| Dose | at 5 mg/mL | at 10 mg/mL | at 20 mg/mL |
|---|---|---|---|
| 2.5 mg | 50 | 25 | 12.5 |
| 5 mg | 100 | 50 | 25 |
| 7.5 mg | over 100 | 75 | 37.5 |
| 10 mg | over 100 | 100 | 50 |
| 12.5 mg | over 100 | over 100 | 62.5 |
| 15 mg | over 100 | over 100 | 75 |
The strength is the mg in the vial divided by the mL of liquid in it: 10 mg with 2 mL of water is 5 mg per mL, 10 mg with 1 mL is 10 mg per mL. Read both numbers from your vial’s label, or from what you added to it.
Pens, vials and the calculator
Zepbound and Mounjaro single-dose pens and KwikPens give the dose printed on them and are not marked in units, so there is nothing to convert. The calculator is for a vial drawn up with a syringe, or for a cartridge in a reusable U-100 pen.
The example in the calculator. A multi-dose vial holds 10 mg in 2.4 mL, 4.17 mg per mL. A 2.5 mg dose is a quarter of the vial: 2.4 mL ÷ 4 = 0.6 mL, which is 60 units on a U-100 syringe, and the vial holds 4 doses, as its label says.
Other calculators
- Semaglutide units to mgThe mg in the units you draw of a semaglutide vial, or the units for a dose, from the strength printed on the vial.
- Retatrutide dosage calculatorUnits to draw for a retatrutide dose, from the mg in the vial and the water you added.
- Insulin syringe units to mLUnits on a U-100 insulin syringe in mL, and mL in units.
- GLP-1 dosage chartsStart, step-up, maintenance and maximum doses of each GLP-1 medicine as its FDA label gives them, with the label's date.
Questions
How many units is 2.5 mg of tirzepatide?
It depends on the strength of the vial. At 5 mg per mL it is 50 units, at 10 mg per mL 25 units, at 20 mg per mL 12.5 units. In the label’s multi-dose vial (10 mg in 2.4 mL) it is 0.6 mL, 60 units.
How many units is 5 mg of tirzepatide?
At 10 mg per mL it is 50 units, at 20 mg per mL 25 units. At 5 mg per mL it is 100 units, a full 1 mL syringe.
Can I use the pen mode with a Zepbound or Mounjaro pen?
No. Those pens give the dose printed on them and have no unit scale. The pen mode is for reusable U-100 pens that take a 3 mL cartridge.
Why does my dose need more than one syringe?
Because the vial is weak for that dose: over 100 units does not fit a 1 mL syringe. The answer then gives the number of draws; a stronger vial, with less liquid for the same mg, puts the dose in one.
Sources
- Zepbound (tirzepatide) injection, prescribing informationFDA, label of 2026-09-10. 2.1 and 2.2: start, steps, maintenance and maximum doses; 2.4: the syringe for vials; 3: pens, vials and KwikPens.
- Mounjaro (tirzepatide) injection, prescribing informationFDA, label of 2026-09-01. 2.1: start, steps and maximum doses for adults and children; 3: strengths.
- BD Insulin Syringe, 510(k) K190054FDA, cleared 2019-10-21. U-100 syringes of 0.3, 0.5 and 1 mL and their lines.