The Zepbound pen dose schedule
Zepbound pens are prefilled at a fixed weekly dose, so you select the pen for your step rather than measuring. The label's titration starts at the lowest step and increases roughly every four weeks as tolerated, mirroring tirzepatide's diabetes schedule.
Because the pen is fixed-dose, tirzepatide's higher milligram steps only become a measuring task if you switch to a compounded 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
Zepbound pens vs compounded tirzepatide vials
A compounded tirzepatide vial is reconstituted and drawn by hand, unlike a Zepbound pen. Picking a bacteriostatic water volume that keeps your weekly dose on readable syringe units is the main task — and it changes as you titrate up through the schedule.
On Zepbound pens you do not need the calculator. On a compounded vial dosed to a comparable schedule, the tirzepatide calculator below turns each target into the units to draw.
- Pen = fixed dose, no math
- Compounded vial = you calculate the draw and units
- Re-check the units each time you step the dose up
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.