The Mounjaro pen dose schedule
Mounjaro pens are prefilled at a fixed weekly dose; you use the pen for your current step rather than measuring anything. The label's titration begins at the lowest step and increases roughly every four weeks as tolerated.
Tirzepatide schedules climb to higher milligram numbers than semaglutide, but because pens are fixed-dose, the larger numbers never become a measuring problem until you move to a vial.
- Standard weekly steps: 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg
- 2.5 mg is a starting step for tolerability, not a maintenance dose
- Pens are fixed-dose — no reconstitution or unit math
Mounjaro pens vs compounded tirzepatide vials
Compounded tirzepatide comes as a vial, not a metered pen, so you reconstitute and draw it yourself. With tirzepatide's higher milligram doses, the bacteriostatic water volume you choose has a big effect on how many units you draw — which is exactly what the calculator solves.
On Mounjaro pens you do not need the calculator. On a compounded vial dosed to a comparable schedule, the tirzepatide calculator below turns each step into the units to draw.
- Pen = fixed dose, no math
- Compounded vial = you calculate concentration, draw volume, and units
- Higher mg doses make your BAC water choice matter more
Compounded tirzepatide reference
U100 units to draw for each common Tirzepatide dose, by vial size, reconstituted with 2 mL of bacteriostatic water. Change the water volume in the calculator above to recompute for your own setup.
| Vial | Concentration | 2.5 mg | 5 mg | 7.5 mg | 10 mg | 12.5 mg |
|---|---|---|---|---|---|---|
| 5 mg | 2.5 mg/mL | 100 u(1 mL) | 200 u(2 mL) | 300 u(3 mL) | 400 u(4 mL) | 500 u(5 mL) |
| 10 mg | 5 mg/mL | 50 u(0.5 mL) | 100 u(1 mL) | 150 u(1.5 mL) | 200 u(2 mL) | 250 u(2.5 mL) |
| 15 mg | 7.5 mg/mL | 33.3 u(0.33 mL) | 66.7 u(0.67 mL) | 100 u(1 mL) | 133.3 u(1.33 mL) | 166.7 u(1.67 mL) |
Educational reference only — not a dose recommendation. Units assume a U100 insulin syringe (100 units = 1 mL on U-100). Always confirm against your own vial, diluent, and clinician or pharmacy instructions.