Tirzepatide Reconstitution Calculator
BAC water, concentration & dose-to-units charts
Work out how much bacteriostatic water to add to a tirzepatide vial and what each dose becomes in syringe units, using the charts below — for example, a 30 mg vial in 3 mL of water is 10 mg/mL, so a 5 mg dose is 0.5 mL, or 50 units on a U-100 syringe. Compounded tirzepatide is not the same as branded Mounjaro or Zepbound; always confirm against the product label and your prescriber.
How tirzepatide reconstitution works
Compounded or research tirzepatide is supplied as a freeze-dried (lyophilized) powder that you dissolve with bacteriostatic water before measuring a dose. The concentration is the vial strength divided by the water you add — a 30 mg vial in 3 mL of water is 10 mg/mL.
Once you know the concentration, your dose volume is the dose divided by the concentration, and on a U-100 insulin syringe that volume × 100 gives the number of unit marks to draw. Higher-strength vials (40–60 mg) reconstituted to a higher concentration keep larger 10–15 mg doses inside a single 1 mL syringe.
Reconstitution chart: concentration by tirzepatide vial size and water added
| Vial size | +1 mL | +2 mL | +3 mL | +5 mL |
|---|---|---|---|---|
| 10 mg | 10 mg/mL | 5 mg/mL | 3.33 mg/mL | 2 mg/mLBest |
| 15 mg | 15 mg/mL | 7.5 mg/mL | 5 mg/mL | 3 mg/mL |
| 20 mg | 20 mg/mL | 10 mg/mL | 6.67 mg/mL | 4 mg/mL |
| 30 mg | 30 mg/mL | 15 mg/mL | 10 mg/mL | 6 mg/mL |
| 40 mg | 40 mg/mL | 20 mg/mL | 13.3 mg/mL | 8 mg/mL |
| 60 mg | 60 mg/mL | 30 mg/mL | 20 mg/mL | 12 mg/mL |
Tirzepatide dose to syringe units (by concentration)
| Weekly dose | 5 mg/mL | 10 mg/mL | 20 mg/mL |
|---|---|---|---|
| 2.5 mg | 0.5 mL → 50 | 0.25 mL → 25 | 0.13 mL → 13Best |
| 5 mg | 1.0 mL → 100 | 0.5 mL → 50 | 0.25 mL → 25 |
| 7.5 mg | 1.5 mL → 150* | 0.75 mL → 75 | 0.38 mL → 38 |
| 10 mg | 2.0 mL → 200* | 1.0 mL → 100 | 0.5 mL → 50 |
| 12.5 mg | 2.5 mL → 250* | 1.25 mL → 125* | 0.63 mL → 63 |
| 15 mg | 3.0 mL → 300* | 1.5 mL → 150* | 0.75 mL → 75 |
How to reconstitute a tirzepatide vial
Dosing, storage & safety
Tirzepatide is dosed once weekly and titrated from 2.5 mg upward in 2.5 mg steps to manage gastrointestinal side effects. This calculator only does the reconstitution and unit math — your titration schedule should come from a clinician and the prescribing information.
Bacteriostatic water contains benzyl alcohol as a preservative, so a reconstituted vial can be used for multiple draws; keep it refrigerated and labeled with its concentration and date. Compounded tirzepatide is not FDA-evaluated for identity or potency the way branded pens are, so only obtain and use it under appropriate medical supervision, and confirm doses with your pharmacist.
Frequently Asked Questions
30 mg in 1 mL is 30 mg/mL; in 2 mL is 15 mg/mL; in 3 mL is 10 mg/mL. A common choice is 3 mL for 10 mg/mL, which makes a 5 mg dose 0.5 mL (50 units). Use the reconstitution chart above to match your dose.
At 10 mg/mL, 5 mg is 0.5 mL, or 50 units on a U-100 insulin syringe. At 20 mg/mL it is 0.25 mL (25 units). Units = (dose ÷ concentration) × 100.
No. Branded Mounjaro and Zepbound come premeasured in single-dose pens or auto-injectors and require no mixing. Reconstitution only applies to vialed or compounded tirzepatide powder.
Pick a concentration that keeps your usual dose under 100 units (a full 1 mL syringe). For 10–15 mg doses, 20 mg/mL keeps the volume small and easy to measure; for 2.5–5 mg, 5–10 mg/mL works well.
Add bacteriostatic water down the vial wall, swirl gently until clear (do not shake), then label with the concentration and date and refrigerate. Follow the step-by-step guide and chart above and confirm against the product label.
Yes. Shotlee stores your vial concentration, logs each weekly dose and side effect, and sends reminders so you never have to recompute. It is free.
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