Tirzepatide
How to reconstitute the 20 mg vial and convert any target dose into insulin units. Tirzepatide is the prescription drug Mounjaro/Zepbound, dosed once weekly per its FDA label (2.5 mg start, max 15 mg). The approved product is a metered pen with no reconstitution; the math here is for research vials only.
Calculate for your vial
Enter the mg on your Tirzepatide vial, the bacteriostatic water you added, and your target dose — it works out the exact units to draw on a U-100 insulin syringe, for whatever you personally have.
Reconstitution Calculator
Check the decimal. A misplaced decimal point here is a 10× dosing error. Re-read every number, and confirm your dose with a licensed clinician before you draw.
Educational only — not a dosing recommendation. This tool does the measurement math; it does not tell you what to take. On a U-100 insulin syringe, 100 units = 1 mL.
Dosing schedule
Tirzepatide · fixed weekly step-up schedule
A fixed weekly titration ladder. Heavier individuals more often titrate toward the 10–15 mg maintenance doses (the largest weight loss), while lighter responders can hold at 5 mg.
- 12.5 mg/wkWeeks 1–4Starting dose (initiation only)
- 25 mg/wkWeeks 5–8Maintenance dose
- 37.5 mg/wkWeeks 9–12Step-up
- 410 mg/wkWeeks 13–16Maintenance dose
- 512.5 mg/wkWeeks 17–20Step-up
- 615 mg/wkWeek 21+Maintenance / max
Everyone starts at 2.5 mg and increases in 2.5 mg steps no sooner than every 4 weeks — the approved maintenance doses are 5, 10, or 15 mg (7.5 and 12.5 are step-ups, not endpoints). Heavier people more commonly titrate toward 10–15 mg; lighter responders can hold at 5 mg. The dose is chosen by tolerability and response under medical supervision, not from a weight calculation.
Source: FDA label — Zepbound® (tirzepatide). Educational only — not medical advice and not a dosing recommendation. Any dosing decision belongs with a licensed clinician.
1 · Find your dose
Pick what you're using Tirzepatide for and how much bacteriostatic water you added — this pulls out the exact units to draw and how often people report using it.
Recommended Dose Escalation Schedule The recommended starting dosage is 2.5 mg injected subcutaneously once weekly for 4 weeks. Increase the dosage in 2.5 mg increments after at least 4 weeks until recommended maintenance dosage is achieved. ( 2.1 ) Consider treatment response and tolerability when selecting the maintenance dosage. ( 2.1 ) Recommended Maintenance and Maximum Dosage Weight Reduction and Long-Term Maintenance: 5 mg, 10 mg, or 15 mg injected subcutaneously once weekly. ( 2.2 ) Obstructive Sleep… (see full FDA label)
- How / how often
- Per the FDA label
Verbatim FDA label (openFDA SPL). Prescription-only; educational, not a recommendation. Source: https://api.fda.gov/drug/label.json?search=openfda.generic_name%3A%22tirzepatide%22&limit=5
At 1 mL this 20 mg vial is 20 mg/mL (200 mcg per unit). Use the full matrix below to convert a specific amount into U-100 units — measurement math, not a recommendation.
2 · Reconstitute it cleanly, step by step
How to turn the 20 mg powder into a measured liquid with clean, sterile technique. More water means each insulin unit holds less peptide — easier to measure small amounts accurately.
1Swab the stoppers
Wipe the rubber top of each vial with an alcohol pad and let it air-dry.
2Draw the water
Pull your bacteriostatic water up into the insulin syringe.
3Reconstitute
Inject it slowly down the inside wall of the peptide vial — never straight onto the powder.
4Swirl to dissolve
Gently swirl until the powder fully dissolves into a clear liquid. Never shake.
5Equalize, then draw
To draw a dose: push in an equal amount of air first to equalize the pressure, then pull your dose.
- 1
Swab both tops
Wipe the rubber top of the bacteriostatic-water vial and the Tirzepatide vial stopper with a fresh alcohol pad, and let them air-dry. Never touch the needle or the stoppers after wiping.
Alcohol swab · let dry - 2
Draw the water
First pull 1 mL of air into the syringe and inject it into the bacteriostatic-water vial to equalize the pressure, then draw your 1 mL of water back out. Inject it into the Tirzepatide vial down the inside glass wall, not onto the powder.
1 mL BAC water - 3
Swirl, don't shake
Gently swirl the 20 mg vial until the powder fully dissolves into a clear liquid. Never shake — shaking can damage the peptide and foam the solution.
Swirl, don't shake - 4
Know your strength
The vial is now 20 mg/mL. Each unit on a U-100 syringe holds about 200 mcg.
20 mg/mL - 5
Re-swab & draw your dose
Wipe the stopper again. With a fresh insulin syringe, pull back 25 units of air and inject it into the vial to equalize the pressure, then draw 25 units (0.25 mL) for a 5 mg dose.
25 units - 6
Store it right
Keep the mixed vial in the fridge, away from light. Use a new sterile syringe every time, never share, and drop used sharps in a proper container.
Refrigerate · fresh needle
What each water volume gives you:
3 · Full units reference
Every bacteriostatic-water volume (rows) against every target dose (columns) — each cell is the U-100 units and the exact draw in mL. The highlighted row is the easiest volume to measure.
| BAC water | Concentration | Per unit | 2.5 mg | 5 mg | 7.5 mg |
|---|---|---|---|---|---|
| 1 mLeasy pick | 20 mg/mL | 200 mcg | 12.5u0.125 mL | 25u0.25 mL | 37.5u0.375 mL |
| 2 mL | 10 mg/mL | 100 mcg | 25u0.25 mL | 50u0.5 mL | 75u0.75 mL |
| 3 mL | 6.67 mg/mL | 66.67 mcg | 37.5u0.375 mL | 75u0.75 mL | 112.5u1.125 mL |
4 · Everyday usage
Tirzepatide is the FDA-approved prescription drug Mounjaro/Zepbound, supplied as a finished metered pen or single-dose vial — there is no patient reconstitution step for the approved product. The figures below are the approved-drug label titration schedule for reference only, not a recommendation to reconstitute a research vial.
FDA-approved label dose (Rx-only)
Label-citedRecommended Dose Escalation Schedule The recommended starting dosage is 2.5 mg injected subcutaneously once weekly for 4 weeks. Increase the dosage in 2.5 mg increments after at least 4 weeks until recommended maintenance dosage is achieved. ( 2.1 ) Consider treatment response and tolerability when selecting the maintenance dosage. ( 2.1 ) Recommended Maintenance and Maximum Dosage Weight Reduction and Long-Term Maintenance: 5 mg, 10 mg, or 15 mg injected subcutaneously once weekly. ( 2.2 ) Obstructive Sleep… (see full FDA label)
- Frequency
- Per the FDA label
Verbatim FDA label (openFDA SPL). Prescription-only; educational, not a recommendation. Source: https://api.fda.gov/drug/label.json?search=openfda.generic_name%3A%22tirzepatide%22&limit=5
Studied: Obesity
Studied in trialsSubcutaneous injection once weekly Dose escalation: 2.5 mg → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mg Duration: 12 months
- Frequency
- Route: subcutaneous
Observational human-trial dose — studied, NOT a target or recommendation. Trial (NCT07492563). Source: https://clinicaltrials.gov/study/NCT07492563
Studied: Alcohol Use Disorder (AUD)
Studied in trialsRadiotracer injection of \[11C\]raclopride during combined PET/MR scan to measure striatal dopamine release (Methylphenidate 0.25 mg/kg injected 45 minutes post radiotracer injection).
- Frequency
- Phase 1
Observational human-trial dose — studied, NOT a target or recommendation. Phase 1 (NCT07559500). Source: https://clinicaltrials.gov/study/NCT07559500
Studied: Obesity
Studied in trialsThe dosage will be adjusted according to standard clinical practice and the investigator's discretion, following the manufacturer's titration schedule (starting at 2.5 mg and increasing up to 15 mg as tolerated).
- Frequency
- Route: subcutaneous
Observational human-trial dose — studied, NOT a target or recommendation. Phase 4 (NCT07588438). Source: https://clinicaltrials.gov/study/NCT07588438
Frequently asked questions
How many insulin units is 2.5 mg of Tirzepatide from a 20 mg vial?
- Reconstituting a 20 mg vial with 1 mL of bacteriostatic water gives 20 mg/mL — about 200 mcg per unit. Drawing 2.5 mg is 0.125 mL, or 12.5 units on a U-100 insulin syringe. This is measurement math, not a dose recommendation.
How many insulin units is 5 mg of Tirzepatide from a 20 mg vial?
- Reconstituting a 20 mg vial with 1 mL of bacteriostatic water gives 20 mg/mL — about 200 mcg per unit. Drawing 5 mg is 0.25 mL, or 25 units on a U-100 insulin syringe. This is measurement math, not a dose recommendation.
Is the approved tirzepatide product reconstituted by the patient?
- No. Mounjaro and Zepbound are finished, FDA-regulated products supplied as metered pens or pre-filled single-dose vials, with no mixing step. The reconstitution math here applies only to lyophilized research vials, which are not the approved medicine. Tirzepatide is prescription-only; dosing belongs with a licensed clinician.
References
WikiPeps is a community reference. Reconstitution figures are deterministic measurement math; usage figures are sourced and labeled. Nothing here is medical advice, a recommendation, or an offer to sell peptides — dosing decisions belong with a licensed clinician.