Tirzepatide Reconstitution Calculator (mg → units)
A 10 mg vial of Tirzepatide mixed with 2 mL of bacteriostatic water holds 5,000 mcg/mL, so a 2.5 mg dose is 0.5 mL — 50 units on a U-100 insulin syringe. Change the vial, water or dose below, or read the chart for other mixes.
Tirzepatide dilution chart: 2.5 mg in units
| Vial | + 1 mL water | + 2 mL water | + 3 mL water | Doses per vial |
|---|---|---|---|---|
| 5 mg | 50 U 0.5 mL · 5,000 mcg/mL | 100 U 1 mL · 2,500 mcg/mL | 150 U 1.5 mL · 1,667 mcg/mL over 1 mL — more than one syringe | 2 |
| 10 mg | 25 U 0.25 mL · 10,000 mcg/mL | 50 U 0.5 mL · 5,000 mcg/mL | 75 U 0.75 mL · 3,333 mcg/mL | 4 |
| 15 mg | 16.7 U 0.167 mL · 15,000 mcg/mL | 33.3 U 0.333 mL · 7,500 mcg/mL | 50 U 0.5 mL · 5,000 mcg/mL | 6 |
| 20 mg | 12.5 U 0.125 mL · 20,000 mcg/mL | 25 U 0.25 mL · 10,000 mcg/mL | 37.5 U 0.375 mL · 6,667 mcg/mL | 8 |
| 30 mg | 8.3 U 0.083 mL · 30,000 mcg/mL | 16.7 U 0.167 mL · 15,000 mcg/mL | 25 U 0.25 mL · 10,000 mcg/mL | 12 |
1 mL = 100 units on a U-100 syringe. Water volume changes the units per dose, never the number of doses in the vial.
Tirzepatide dose steps in units (30 mg vial + 2 mL)
| Dose | Units (U-100) | Volume | Context |
|---|---|---|---|
| 2.5 mg | 16.7 U | 0.167 mL | Starting step, weeks 1–4 |
| 5 mg | 33.3 U | 0.333 mL | First increase |
| 7.5 mg | 50 U | 0.5 mL | +2.5 mg after ≥4 weeks |
| 10 mg | 66.7 U | 0.667 mL | +2.5 mg after ≥4 weeks |
| 12.5 mg | 83.3 U | 0.833 mL | +2.5 mg after ≥4 weeks |
| 15 mg | 100 U | 1 mL | Highest labelled dose |
Mix: 30 mg vial + 2 mL water = 15,000 mcg/mL. Steps follow the 2.5 mg increments in the label titration. At this concentration the 15 mg top step fills a 1 mL syringe exactly; at lower concentrations it will not fit in one draw.
Measuring Tirzepatide: the math that matters
Tirzepatide doses are large compared with most peptides: the label ladder starts at 2.5 mg and climbs in 2.5 mg steps to 15 mg. At those amounts the problem is not a draw that is too small, as it is with BPC-157, but one that is too big. A 10 mg vial mixed with 2 mL gives 5,000 mcg/mL, so 2.5 mg is 0.5 mL, or 50 units, and 10 mg from the same mix would be 200 units, two full 1 mL syringes.
That is why vial size and water volume matter more here than for almost any other compound. The more milligrams per millilitre, the more of the ladder fits in one syringe. A 30 mg vial with 2 mL is 15,000 mcg/mL: 2.5 mg becomes 16.7 units and 15 mg is exactly 100 units. A 5 mg vial with 2 mL is only 2,500 mcg/mL, where 2.5 mg is already a full 100-unit syringe and the vial holds just two doses.
Fractions show up quickly. 2.5 mg at 15,000 mcg/mL is 16.67 units, which you will round to the nearest line; on a syringe marked every 2 units that means drawing to about 16 or 18. Check how much that rounding changes the dose before settling on a mix, and prefer concentrations where your step lands on a whole line.
The branded products do not need any of this. Zepbound comes as single-dose pens or vials of ready-made solution, each strength in 0.5 mL, so there is no reconstitution. The calculator is for lyophilized vials that you mix yourself.
Common Tirzepatide measuring mistakes
- Choosing a low-concentration mix for the first month and then finding the 7.5 mg or 10 mg steps no longer fit in one syringe.
- Using units from a branded 0.5 mL vial as a guide for a reconstituted vial. Their concentrations are different.
- Forgetting how few doses a small vial holds at higher steps: a 10 mg vial is four doses at 2.5 mg but one at 10 mg.
- Rounding 16.7 units down to 16 every week without noticing it is a consistent 4% under-dose.
- Entering the vial size in mcg (10,000) in a field that expects mg.