Tirzepatide dosage calculator
Convert the tirzepatide dose you were prescribed, in milligrams, into units on your syringe. Works for any vial strength, from a licensed medical weight loss clinic in Mission Viejo.
Medically reviewed by Dr. Nezar Dahdal, Medical Director · last reviewed September 2026
Tirzepatide dose calculator
Enter the dose your prescriber gave you and the concentration printed on your vial label. The calculator converts it to units on a U-100 insulin syringe.
Enter your prescribed dose and your vial concentration to see the units.
This converts a dose you have already been prescribed. It does not recommend a dose. Always use the concentration printed on your pharmacy label. If the number here does not match what you were told, stop and call your prescriber before injecting.
Tirzepatide units chart by vial strength
The same conversions as the calculator, for every standard dose step and the vial strengths pharmacies most often dispense. Find your prescribed dose on the left and your vial concentration along the top.
| Prescribed dose | 5 mg/mL vial | 10 mg/mL vial | 20 mg/mL vial |
|---|---|---|---|
| 2.5 mg | 50 units (0.5 mL) | 25 units (0.25 mL) | 12.5 units (0.125 mL) |
| 5 mg | 100 units (1 mL) | 50 units (0.5 mL) | 25 units (0.25 mL) |
| 7.5 mg | 150 units (1.5 mL) | 75 units (0.75 mL) | 37.5 units (0.375 mL) |
| 10 mg | 200 units (2 mL) | 100 units (1 mL) | 50 units (0.5 mL) |
| 12.5 mg | 250 units (2.5 mL) | 125 units (1.25 mL) | 62.5 units (0.625 mL) |
| 15 mg | 300 units (3 mL) | 150 units (1.5 mL) | 75 units (0.75 mL) |
How the conversion works
Tirzepatide is prescribed in milligrams (mg), but a vial is measured in milliliters (mL), and an insulin syringe is marked in units. On a U-100 syringe, 100 units fill 1 mL. So the conversion needs two numbers: the dose you were prescribed, and the concentration printed on your vial.
Units = dose (mg) ÷ concentration (mg/mL) × 100. For example, 2.5 mg from a 10 mg/mL vial is 0.25 mL, which is 25 units on a U-100 syringe.
The same dose from a different-strength vial is a different number of units. That is the most common source of dosing errors with compounded vials, and why a number copied from someone else's chart can be wrong for you.
Compounded tirzepatide and semaglutide are not FDA-approved. They are prepared by a licensed pharmacy for an individual patient, and their strength varies from pharmacy to pharmacy, which is exactly why the concentration on your own label is the number that matters. Brand pens (Zepbound, Mounjaro, Wegovy, Ozempic) deliver a fixed dose and need no conversion.
Checks before every injection
- Read the concentration on the vial label, every time. A refill can come at a different strength.
- Confirm the syringe is U-100 and note its capacity (30, 50 or 100 units).
- If the result looks very different from your last dose, stop and call your prescriber.
- Keep a written record of the dose and units you drew each week.
Sources
- Zepbound (tirzepatide) prescribing information, DailyMed, US National Library of Medicine
- Mounjaro (tirzepatide) prescribing information, DailyMed
- Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med, 2022. PubMed
- FDA: FDA's concerns with unapproved GLP-1 drugs used for weight loss
Answers before you book
How many units is 2.5 mg of tirzepatide?
It depends on your vial. At 5 mg/mL it is 50 units, at 10 mg/mL it is 25 units, and at 20 mg/mL it is 12.5 units on a U-100 syringe. Use the concentration printed on your own label.
How do I convert tirzepatide mg to units?
Divide the prescribed dose in mg by the vial concentration in mg/mL, then multiply by 100. That gives units on a U-100 insulin syringe, where 100 units equal 1 mL.
Why does my number differ from a chart I found online?
Charts assume a particular vial strength. Compounded tirzepatide is dispensed at different concentrations, so the same dose in mg can be a different number of units. Your label, not the chart, is the reference.
Does this calculator tell me what dose to take?
No. It only converts a dose your prescriber has already given you. Starting, increasing or holding a dose is a decision for your prescriber.
Do Zepbound or Mounjaro pens need this conversion?
No. Brand pens deliver a fixed, pre-measured dose. The conversion is for vials drawn up with a syringe.
What if the units are more than my syringe holds?
Do not draw it in two parts on your own. Check the dose and the concentration against your label, then ask your prescriber or pharmacist how it should be measured.
Want a clinician to check your plan?
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