Worked example
Add 2 mL of water to a vial holding 10 mg of Tirzepatide. The concentration is 10 ÷ 2 = 5 mg/mL, or 5,000 mcg in every millilitre. On a U-100 syringe, where 100 units make 1 mL, each unit holds 50 mcg and each 10 units hold 500 mcg.
Change the water and only the concentration changes. With 4 mL instead, each 10 units hold 250 mcg, half as much, and any given mass takes twice the units to measure. These numbers illustrate the arithmetic; they are not amounts to use.
Concentration table
Common Tirzepatide vial sizes against common water volumes. The last column is what 10 units on a U-100 syringe hold.
| Vial | Water | Concentration | 10 units (U-100) hold |
|---|---|---|---|
| 5 mg | 1 mL | 5 mg/mL | 500 mcg |
| 5 mg | 2 mL | 2.5 mg/mL | 250 mcg |
| 5 mg | 3 mL | 1.667 mg/mL | 166.7 mcg |
| 10 mg | 1 mL | 10 mg/mL | 1 mg |
| 10 mg | 2 mL | 5 mg/mL | 500 mcg |
| 10 mg | 3 mL | 3.333 mg/mL | 333.3 mcg |
| 15 mg | 1 mL | 15 mg/mL | 1.5 mg |
| 15 mg | 2 mL | 7.5 mg/mL | 750 mcg |
| 15 mg | 3 mL | 5 mg/mL | 500 mcg |
| 20 mg | 1 mL | 20 mg/mL | 2 mg |
| 20 mg | 2 mL | 10 mg/mL | 1 mg |
| 20 mg | 3 mL | 6.667 mg/mL | 666.7 mcg |
| 30 mg | 1 mL | 30 mg/mL | 3 mg |
| 30 mg | 2 mL | 15 mg/mL | 1.5 mg |
| 30 mg | 3 mL | 10 mg/mL | 1 mg |
| 60 mg | 1 mL | 60 mg/mL | 6 mg |
| 60 mg | 2 mL | 30 mg/mL | 3 mg |
| 60 mg | 3 mL | 20 mg/mL | 2 mg |
Notes for Tirzepatide vial math
- Tirzepatide research vials run from 5 mg to 60 mg. A 60 mg vial in 2 mL is 30 mg/mL, where a single unit on a U-100 syringe holds 300 mcg. At that strength the reading precision of the syringe matters more than anything else on this page.
- If the amount you enter would take more than the syringe holds, the calculator flags it. Switching from a 0.3 mL to a 1 mL syringe changes the units shown, never the mass in the vial.
- Approved tirzepatide solutions are labeled in mg per 0.5 mL. If you are comparing against a label, convert both to mg/mL first; the calculator shows mg/mL for every input.
Storage and handling
- For the approved pens, the US prescribing information allows storage unrefrigerated (up to 30 °C) for up to 21 days; otherwise they are refrigerated and must not be frozen. That data applies to Lilly's formulation, not to reconstituted research powder.
- No validated in-use stability data exists for reconstituted research tirzepatide. Keep reconstituted vials refrigerated, protected from light, and labeled with date and concentration.