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How-to · reconstitution
Put 1 mL of bacteriostatic water into the 60 mg Tirzepatide vial. That makes 60.00 mg/mL. A 2.5 mg dose is then 4.2 units on a U-100 syringe.
More water makes a weaker mix and a bigger draw. Less water makes a stronger mix and a smaller one. The amount of Tirzepatide in the glass never changes. Only the number of marks it takes does.
Tirzepatide is the drug in Zepbound and Mounjaro. It works on two gut hormone signals involved in appetite and blood sugar.
| Water added | Concentration | Per U-100 unit | Example: 2.5 mg = |
|---|---|---|---|
| 1 mL | 60.00 mg/mL | 600 mcg | 4.2 units |
| 2 mL | 30.00 mg/mL | 300 mcg | 8.3 units |
| 3 mL | 20.00 mg/mL | 200 mcg | 12.5 units |
Straight arithmetic: concentration = 60 mg ÷ water, and 1 U-100 unit = 0.01 mL. The example column shows the math at 2.5 mg; it is not a dose recommendation.
Which volume to use is a practical choice rather than a dose. Pick the one that puts your draw somewhere you can actually read it on the syringe. The flags in the last column mark where that fails. “Hard to measure” means the draw is too small to judge by eye. “Won’t fit” means it is bigger than one U-100 syringe holds.
The table above uses one worked example. These are the published quantities, converted into marks on a U-100 barrel at each water volume for a 60 mg vial. Where a quantity was never studied by injection, the row says so.
2.5 mg once weekly for 4 weeks, under the skin.
| Water added | Concentration | Draw |
|---|---|---|
| 1 mL | 60.00 mg/mL | 4.2 units |
| 2 mL | 30.00 mg/mL | 8.3 units |
| 3 mL | 20.00 mg/mL | 12.5 units |
FDA labelZepbound (tirzepatide) — FDA-approved Prescribing Information · retrieved 2026-07-22
5–15 mg once weekly, under the skin. (5, 10, or 15 mg).
| Water added | Concentration | Draw, low to high |
|---|---|---|
| 1 mL | 60.00 mg/mL | 8.3 to 25.0 units |
| 2 mL | 30.00 mg/mL | 16.7 to 50.0 units |
| 3 mL | 20.00 mg/mL | 25.0 to 75.0 units |
FDA labelZepbound (tirzepatide) — FDA-approved Prescribing Information · retrieved 2026-07-22
The vial contains twenty-four worked doses, while the stated storage window covers four. About five sixths would remain in this example.
Twenty of the twenty-four doses in this vial expire before the window closes. That is not a rounding loss or a residue — it is most of the vial.
Nobody buying this size intends that, and the mixing table gives no hint of it. It is the reason this page exists separately from the smaller ones.
This is the only tirzepatide vial where all three water volumes drop the draw between graduations. At the least water the plunger sits at a handful of units with no line to stop at.
This is the hardest combination to measure accurately: a strong mix, a small draw and no printed syringe mark. It occurs with the largest vial, not the smallest.
Read against the top of the labeled schedule it becomes the mirror image of the smallest vial. Four doses, four weeks, nothing wasted.
So this is a vial for somebody who finished escalating months ago. Bought at the start of a schedule it is the worst purchase on the ladder.
The table shows the offered water volumes. The calculator does the same arithmetic for any volume and any syringe, and shows its working line by line.
Open the Tirzepatide calculator →The arithmetic on this page is only half the question. These are the pages that carry the other half.