VialTirzepatide Reconstitution Calculator
Compounded tirzepatide vials vary in strength and in how much diluent your pharmacy instructs you to add — which means the concentration changes from vial to vial. This free calculator turns vial strength, diluent volume and your prescribed dose into an exact draw volume, with a visual syringe fill line.
Reference dose escalation, once weekly
The escalation below is the one published in the clinical labelling: 2.5 mg every week for the first four weeks, then increases of 2.5 mg no sooner than every four weeks. Note that only 5, 10 and 15 mg are described as maintenance doses — the intervening steps exist to get you there tolerably.
| Weekly dose | Published window | Role |
|---|---|---|
| 2.5 mg | Weeks 1–4 | Initiation only — not intended as glycaemic control |
| 5 mg | Weeks 5–8 | Lowest maintenance dose |
| 7.5 mg | Weeks 9–12 | Escalation step |
| 10 mg | Weeks 13–16 | Maintenance dose |
| 12.5 mg | Weeks 17–20 | Escalation step |
| 15 mg | Week 21 on | Maximum weekly dose |
This table describes the branded prescription medicine, not compounded or research material, which follows no approved schedule. Tirzepatide is prescription-only: your own starting dose, pace of increase and maintenance dose are decided by your prescriber. VialDose is a unit converter — it cannot tell you what your dose should be.
Source: tirzepatide prescribing information and Eli Lilly medical information — starting dose 2.5 mg once weekly for 4 weeks, then 2.5 mg increments after at least 4 weeks on the current dose, maximum 15 mg weekly in adults.
Why tirzepatide math deserves extra care
Tirzepatide vials are commonly supplied at higher strengths than other GLP-1 class peptides, and small draw volumes amplify concentration errors: on a 100U insulin syringe, one unit is only 0.01 mL. A 2× concentration mistake — mixing up a 1 mL and a 2 mL diluent instruction — is a 2× dose mistake. The calculator blocks over-ranges instead of rounding them away, and always shows the exact draw to 4 decimals beneath the readable figure.
Worked example (round numbers)
A 10 mg vial mixed with 1 mL gives 10 mg/mL. A prescribed 2.5 mg dose draws 2.5 ÷ 10 = 0.25 mL = 25 units on a 100U insulin syringe. If the vial were diluted with 2 mL instead, the same dose would be 0.5 mL = 50 units. Same vial, same dose, different draw — the diluent volume is the number people get wrong.
Related guides
The VialDose app logs doses, rotates sites and counts down vial volume — private by design.