Tirzepatide dosage chart: mg to units
Updated 24 October 2026
On a U-100 insulin syringe, 1 unit is 0.01 mL. How many units a tirzepatide dose takes depends only on the concentration of your vial, in mg per mL. The same 2.5 mg dose is 50 units from a 5 mg/mL vial and 12.5 units from a 20 mg/mL vial, so a chart is only useful once you know your vial's concentration.
How many units is 2.5 mg of tirzepatide?
At 10 mg/mL, 2.5 mg is 25 units (0.25 mL) on a U-100 insulin syringe. At 5 mg/mL it is 50 units (0.5 mL), and at 20 mg/mL it is 12.5 units (0.125 mL).
A Zepbound single-dose vial is different: every strength, from 2.5 mg to 15 mg, holds its dose in 0.5 mL, and Lilly's instructions draw 0.5 mL with a syringe marked in mL. Use the syringe your prescriber recommends.
Tirzepatide units calculator
Enter the concentration printed on your vial and your prescribed dose.
Draw 25 units (0.25 mL)
2.5 mg at 10 mg/mL on a U-100, 1 mL (100 units) syringe. Round to the nearest mark your syringe has.
Draw to 25 units
U-100, 1 mL (100 units) insulin syringe
Free, no account needed. Your vials stay on this device.
Tirzepatide dosage chart (U-100 syringe)
Find your dose on the left and your vial's concentration across the top. "Over 1 mL" means the dose doesn't fit in a single 1 mL syringe, which is a reason to check the concentration with your pharmacy.
| Dose | 5 mg/mL | 10 mg/mL | 15 mg/mL | 20 mg/mL | 30 mg/mL |
|---|---|---|---|---|---|
| 2.5 mg | 50 units (0.5 mL) | 25 units (0.25 mL) | 16.7 units (0.167 mL) | 12.5 units (0.125 mL) | 8.3 units (0.083 mL) |
| 5 mg | 100 units (1 mL) | 50 units (0.5 mL) | 33.3 units (0.333 mL) | 25 units (0.25 mL) | 16.7 units (0.167 mL) |
| 7.5 mg | over 1 mL | 75 units (0.75 mL) | 50 units (0.5 mL) | 37.5 units (0.375 mL) | 25 units (0.25 mL) |
| 10 mg | over 1 mL | 100 units (1 mL) | 66.7 units (0.667 mL) | 50 units (0.5 mL) | 33.3 units (0.333 mL) |
| 12.5 mg | over 1 mL | over 1 mL | 83.3 units (0.833 mL) | 62.5 units (0.625 mL) | 41.7 units (0.417 mL) |
| 15 mg | over 1 mL | over 1 mL | 100 units (1 mL) | 75 units (0.75 mL) | 50 units (0.5 mL) |
The formula
units = dose (mg) ÷ concentration (mg/mL) × 100
Example: 7.5 mg from a 15 mg/mL vial is 7.5 ÷ 15 = 0.5 mL, and 0.5 mL × 100 = 50 units. The ×100 holds only for U-100 syringes. A U-40 syringe has 40 units per mL, so the same dose would read 20 units on it.
Reading the concentration on a vial label
Labels state strength in two ways. "10 mg/mL" is the concentration already. "20 mg/2 mL" is the whole vial, so divide: 20 mg ÷ 2 mL = 10 mg/mL. Use the concentration, never the total, in the calculator.
Tirzepatide dose steps in the FDA label
The Zepbound label sets the escalation your prescriber works from (FDA label, Lilly):
- Start at 2.5 mg once weekly for 4 weeks. 2.5 mg is a starting dose, not a maintenance dose.
- Then 5 mg once weekly.
- Increase in 2.5 mg steps, each after at least 4 weeks on the current dose.
- The maximum is 15 mg once weekly.
Your prescriber may hold you at a dose longer or choose a lower maintenance dose.
Compounded tirzepatide
Compounded tirzepatide comes in multi-dose vials whose concentration varies by pharmacy, so read the label each time you get a new vial. Compounded drugs are not FDA-approved, and the FDA does not review them for safety, effectiveness or quality before they are sold (FDA).