Tirzepatide Dosage Calculator
Tirzepatide comes three ways and each one needs different arithmetic: the branded pen or single-dose vial, a compounded pre-mixed multi-dose vial with a concentration printed on the label, or a dry-powder vial you reconstitute yourself.
This page handles the last two. Enter the powder vial and water, or switch to pre-mixed mode and enter the concentration from your pharmacy label, and you get the units to draw for any milligram dose.
FDA labelAn approved product exists and its label states the dose. · Reviewed by the FormBlends Editorial Standards Team · 2026-09-03
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FDA compounding status (2026-08-27): Eligible with limits. Same essentially-a-copy constraint as semaglutide. Full status table and sources
What the Tirzepatide dose evidence actually is
Label: 2.5 mg once weekly for four weeks, then increase in 2.5 mg steps no sooner than every four weeks. Maintenance 5, 10 or 15 mg. Maximum 15 mg.
Tirzepatide has an FDA label. Zepbound starts at 2.5 mg once weekly for four weeks, then increases in 2.5 mg steps at intervals of at least four weeks, with maintenance doses of 5 mg, 10 mg or 15 mg and a maximum of 15 mg weekly. Its half-life is about five days, which is why it is dosed weekly and why a missed dose has a four-day grace window on the label.
Compounded tirzepatide follows the same milligram schedule but the concentration varies by pharmacy: 8, 10, 17 and 20 mg per mL are all common in pre-mixed vials, and dry-powder vials run from 5 mg to 60 mg. The dose does not change between pharmacies. The units do, every time.
Tirzepatide units at each water volume
The table uses a 30 mg vial. Each cell is the draw on a U-100 insulin syringe for that dose at that water volume. Cells above 100 units do not fit a 1 mL syringe; cells below 10 units sit in the part of a 1 mL barrel where measurement error rises, and a 0.5 mL or 0.3 mL syringe reads them better.
| Dose | 30 mg + 1 mL30 mg/mL | 30 mg + 2 mL15 mg/mL | 30 mg + 3 mL10 mg/mL | 30 mg + 5 mL6 mg/mL |
|---|---|---|---|---|
| 2.5 mg | 8.3 units | 16.7 units | 25 units | 41.7 units |
| 5 mg | 16.7 units | 33.3 units | 50 units | 83.3 units |
| 10 mg | 33.3 units | 66.7 units | 100 units | 167 (does not fit) |
Worked example: 30 mg with 3 mL is 10 mg per mL, so 2.5 mg (2.5 mg, the labelled starting dose) is 26 units, or 0.25 mL.
Mixing Tirzepatide
For a dry-powder vial, 10 mg per mL is the concentration most people aim for because it makes the mental math easy: 10 units per milligram, so 2.5 mg is 25 units and 5 mg is 50 units. A 30 mg vial needs 3 mL to get there; a 60 mg vial needs 6 mL, which most vials cannot hold, so 60 mg vials usually end up at 15 or 20 mg per mL.
For a pre-mixed vial, ignore what you read on forums and use the label. A label that says 1.1 mL means 110 units, not 11. A label that says 10 mg per mL means a 2.5 mg dose is 25 units. If the label gives the dose in millilitres and your syringe reads in units, multiply millilitres by 100.
Storing Tirzepatide after mixing
Compounded vials carry a pharmacy beyond-use date on the label; that date wins over any generic rule. Reconstituted powder vials should be refrigerated at 2 to 8 degrees Celsius and treated as good for no more than 28 days after the first puncture.
Tirzepatide calculator questions
How much bac water for 30 mg tirzepatide?
Three millilitres gives 10 mg per mL, so 2.5 mg is 25 units, 5 mg is 50 units and 7.5 mg is 75 units. Two millilitres gives 15 mg per mL and the same doses become 17, 33 and 50 units. The 3 mL mix keeps every labelled dose on an easy tick mark.
How many units is 2.5 mg of tirzepatide?
Twenty-five units at 10 mg per mL. Thirty-one units at 8 mg per mL. Fifteen units at 17 mg per mL (rounded from 14.7). Twelve and a half units at 20 mg per mL. Check the concentration on your vial before you trust any number.
My label says 1.1 mL but a calculator says 11 units. Which is right?
The label. One millilitre is 100 units on a U-100 insulin syringe, so 1.1 mL is 110 units. Eleven units would be a tenfold underdose. This exact confusion is one of the most common in patient forums, which is why every result on this page shows both millilitres and units.
Can I split a weekly tirzepatide dose into two injections?
The label describes once-weekly dosing. Some patients and prescribers split doses to manage side effects; that is a decision for your prescriber. The calculator's dose splitter shows the units for each half if you have been told to do this.
Sources
Tirzepatide guide
Evidence, mechanism, side effects and regulatory status.
Tirzepatide through FormBlends
Provider review, licensed pharmacy, labelled concentration.
The full peptide calculator
All peptides, pre-mixed vials, blends, mistakes and concentration changes.
Free downloads built from this calculator's math
Peptide Dosing and Reconstitution Chart 2026
20 pages, 12 peptides, every vial size, units at five water volumes, printable vial labels. PDF.
Bacteriostatic Water Cheat Sheet
How much to add, what one unit holds, the 28-day rule stated correctly, four mistakes to avoid. PDF.
28-Day GLP-1 Injection Tracker
Dose, units drawn, site, weight, side effects and the vial counting down. PDF and spreadsheet.
Other peptide calculators
Arithmetic only. This page converts the dose you enter into units and millilitres. It does not recommend a dose. Tirzepatide is a prescription medication; follow your label. FormBlends connects patients with licensed providers and pharmacies and does not prescribe or dispense.
