Dosage calculator
Tirzepatide Dosage Calculator: Reconstitution and Units
Quick answer
To calculate tirzepatide dosage, divide your target dose (mg) by the vial concentration. Concentration = vial mg ÷ diluent mL. For a 10 mg vial with 2 mL BAC water: concentration is 5 mg/mL. A 5 mg dose equals 1.0 mL (100 U-100 units) on a standard insulin syringe.
- Updated October 17, 2026
- 2 sources
- Educational use · not medical advice
Tirzepatide Calculator Tool
Enter your vial strength, BAC water volume, and target dose below. The calculator outputs concentration (mg/mL), draw volume (mL), and U-100 units. Educational and research use only.
Fills the calculator below. Choose your BAC water in the calculator.
On this page
How much bac water for each tirzepatide vial size
BAC water doesn't change how much tirzepatide is in the vial, only how concentrated the mix is. Less water makes each unit stronger; more water spreads the same amount over more units. Each answer uses a 2.5 mg dose, the starting dose in the Mounjaro and Zepbound labels, so the mixes are easy to compare.
How much bac water for 5 mg tirzepatide?
It's your choice: the water sets the strength of the mix, not the amount of tirzepatide. With 1 mL, a 5 mg vial is 5 mg/mL and a 2.5 mg dose is 50 units on a U-100 syringe; 2 mL gives 2.5 mg/mL (100 units); 3 mL gives 1.67 mg/mL (150 units, more than a 1 mL syringe holds).
Every dose for a 5 mg vialHow much bac water for 10 mg tirzepatide?
It's your choice: the water sets the strength of the mix, not the amount of tirzepatide. With 1 mL, a 10 mg vial is 10 mg/mL and a 2.5 mg dose is 25 units on a U-100 syringe; 2 mL gives 5 mg/mL (50 units); 3 mL gives 3.33 mg/mL (75 units).
Every dose for a 10 mg vialHow much bac water for 15 mg tirzepatide?
It's your choice: the water sets the strength of the mix, not the amount of tirzepatide. With 1 mL, a 15 mg vial is 15 mg/mL and a 2.5 mg dose is 16.7 units on a U-100 syringe; 2 mL gives 7.5 mg/mL (33.3 units); 3 mL gives 5 mg/mL (50 units).
Every dose for a 15 mg vialHow much bac water for 20 mg tirzepatide?
It's your choice: the water sets the strength of the mix, not the amount of tirzepatide. With 1 mL, a 20 mg vial is 20 mg/mL and a 2.5 mg dose is 12.5 units on a U-100 syringe; 2 mL gives 10 mg/mL (25 units); 3 mL gives 6.67 mg/mL (37.5 units).
Every dose for a 20 mg vialHow much bac water for 30 mg tirzepatide?
It's your choice: the water sets the strength of the mix, not the amount of tirzepatide. With 1 mL, a 30 mg vial is 30 mg/mL and a 2.5 mg dose is 8.3 units on a U-100 syringe; 2 mL gives 15 mg/mL (16.7 units); 3 mL gives 10 mg/mL (25 units).
Every dose for a 30 mg vialHow much bac water for 40 mg tirzepatide?
It's your choice: the water sets the strength of the mix, not the amount of tirzepatide. With 1 mL, a 40 mg vial is 40 mg/mL and a 2.5 mg dose is 6.3 units on a U-100 syringe; 2 mL gives 20 mg/mL (12.5 units); 3 mL gives 13.33 mg/mL (18.8 units).
Every dose for a 40 mg vialHow much bac water for 60 mg tirzepatide?
It's your choice: the water sets the strength of the mix, not the amount of tirzepatide. With 1 mL, a 60 mg vial is 60 mg/mL and a 2.5 mg dose is 4.2 units on a U-100 syringe; 2 mL gives 30 mg/mL (8.3 units); 3 mL gives 20 mg/mL (12.5 units).
Every dose for a 60 mg vialTirzepatide Reconstitution by Vial Size
Doses are the steps in the FDA labels for Mounjaro and Zepbound: 2.5 mg once weekly for 4 weeks, then 5 mg, then up in 2.5 mg steps after at least 4 weeks on each dose, to a maximum of 15 mg once weekly (see sources). Those products come ready to inject; these tables are for powder vials mixed with BAC water. They show the math for each mix, not which dose to take.
- Each cell is the U-100 syringe reading for that dose, with the mL to draw under it.
- Over 1 mL more than a 1 mL (100-unit) syringe holds: the calculator splits it into more than one injection.
- Over vial the dose is more than the vial contains.
5 mg tirzepatide vial
1 mL BAC water = 5 mg/mL · 2 mL BAC water = 2.5 mg/mL · 3 mL BAC water = 1.67 mg/mL
| Weekly dose | 1 mL | 2 mL | 3 mL |
|---|---|---|---|
| 2.5 mg | 50 units0.5 mL | 100 units1 mL | 150 units1.5 mLOver 1 mL |
| 5 mg | 100 units1 mL | 200 units2 mLOver 1 mL | 300 units3 mLOver 1 mL |
| 7.5 mg | Over vial | Over vial | Over vial |
| 10 mg | Over vial | Over vial | Over vial |
| 12.5 mg | Over vial | Over vial | Over vial |
| 15 mg | Over vial | Over vial | Over vial |
10 mg tirzepatide vial
1 mL BAC water = 10 mg/mL · 2 mL BAC water = 5 mg/mL · 3 mL BAC water = 3.33 mg/mL
| Weekly dose | 1 mL | 2 mL | 3 mL |
|---|---|---|---|
| 2.5 mg | 25 units0.25 mL | 50 units0.5 mL | 75 units0.75 mL |
| 5 mg | 50 units0.5 mL | 100 units1 mL | 150 units1.5 mLOver 1 mL |
| 7.5 mg | 75 units0.75 mL | 150 units1.5 mLOver 1 mL | 225 units2.25 mLOver 1 mL |
| 10 mg | 100 units1 mL | 200 units2 mLOver 1 mL | 300 units3 mLOver 1 mL |
| 12.5 mg | Over vial | Over vial | Over vial |
| 15 mg | Over vial | Over vial | Over vial |
15 mg tirzepatide vial
1 mL BAC water = 15 mg/mL · 2 mL BAC water = 7.5 mg/mL · 3 mL BAC water = 5 mg/mL
| Weekly dose | 1 mL | 2 mL | 3 mL |
|---|---|---|---|
| 2.5 mg | 16.7 units0.17 mL | 33.3 units0.33 mL | 50 units0.5 mL |
| 5 mg | 33.3 units0.33 mL | 66.7 units0.67 mL | 100 units1 mL |
| 7.5 mg | 50 units0.5 mL | 100 units1 mL | 150 units1.5 mLOver 1 mL |
| 10 mg | 66.7 units0.67 mL | 133.3 units1.33 mLOver 1 mL | 200 units2 mLOver 1 mL |
| 12.5 mg | 83.3 units0.83 mL | 166.7 units1.67 mLOver 1 mL | 250 units2.5 mLOver 1 mL |
| 15 mg | 100 units1 mL | 200 units2 mLOver 1 mL | 300 units3 mLOver 1 mL |
20 mg tirzepatide vial
1 mL BAC water = 20 mg/mL · 2 mL BAC water = 10 mg/mL · 3 mL BAC water = 6.67 mg/mL
| Weekly dose | 1 mL | 2 mL | 3 mL |
|---|---|---|---|
| 2.5 mg | 12.5 units0.13 mL | 25 units0.25 mL | 37.5 units0.38 mL |
| 5 mg | 25 units0.25 mL | 50 units0.5 mL | 75 units0.75 mL |
| 7.5 mg | 37.5 units0.38 mL | 75 units0.75 mL | 112.5 units1.13 mLOver 1 mL |
| 10 mg | 50 units0.5 mL | 100 units1 mL | 150 units1.5 mLOver 1 mL |
| 12.5 mg | 62.5 units0.63 mL | 125 units1.25 mLOver 1 mL | 187.5 units1.88 mLOver 1 mL |
| 15 mg | 75 units0.75 mL | 150 units1.5 mLOver 1 mL | 225 units2.25 mLOver 1 mL |
30 mg tirzepatide vial
1 mL BAC water = 30 mg/mL · 2 mL BAC water = 15 mg/mL · 3 mL BAC water = 10 mg/mL
| Weekly dose | 1 mL | 2 mL | 3 mL |
|---|---|---|---|
| 2.5 mg | 8.3 units0.0833 mL | 16.7 units0.17 mL | 25 units0.25 mL |
| 5 mg | 16.7 units0.17 mL | 33.3 units0.33 mL | 50 units0.5 mL |
| 7.5 mg | 25 units0.25 mL | 50 units0.5 mL | 75 units0.75 mL |
| 10 mg | 33.3 units0.33 mL | 66.7 units0.67 mL | 100 units1 mL |
| 12.5 mg | 41.7 units0.42 mL | 83.3 units0.83 mL | 125 units1.25 mLOver 1 mL |
| 15 mg | 50 units0.5 mL | 100 units1 mL | 150 units1.5 mLOver 1 mL |
40 mg tirzepatide vial
1 mL BAC water = 40 mg/mL · 2 mL BAC water = 20 mg/mL · 3 mL BAC water = 13.33 mg/mL
| Weekly dose | 1 mL | 2 mL | 3 mL |
|---|---|---|---|
| 2.5 mg | 6.3 units0.0625 mL | 12.5 units0.13 mL | 18.8 units0.19 mL |
| 5 mg | 12.5 units0.13 mL | 25 units0.25 mL | 37.5 units0.38 mL |
| 7.5 mg | 18.8 units0.19 mL | 37.5 units0.38 mL | 56.3 units0.56 mL |
| 10 mg | 25 units0.25 mL | 50 units0.5 mL | 75 units0.75 mL |
| 12.5 mg | 31.3 units0.31 mL | 62.5 units0.63 mL | 93.8 units0.94 mL |
| 15 mg | 37.5 units0.38 mL | 75 units0.75 mL | 112.5 units1.13 mLOver 1 mL |
60 mg tirzepatide vial
1 mL BAC water = 60 mg/mL · 2 mL BAC water = 30 mg/mL · 3 mL BAC water = 20 mg/mL
| Weekly dose | 1 mL | 2 mL | 3 mL |
|---|---|---|---|
| 2.5 mg | 4.2 units0.0417 mL | 8.3 units0.0833 mL | 12.5 units0.13 mL |
| 5 mg | 8.3 units0.0833 mL | 16.7 units0.17 mL | 25 units0.25 mL |
| 7.5 mg | 12.5 units0.13 mL | 25 units0.25 mL | 37.5 units0.38 mL |
| 10 mg | 16.7 units0.17 mL | 33.3 units0.33 mL | 50 units0.5 mL |
| 12.5 mg | 20.8 units0.21 mL | 41.7 units0.42 mL | 62.5 units0.63 mL |
| 15 mg | 25 units0.25 mL | 50 units0.5 mL | 75 units0.75 mL |
How to Calculate Tirzepatide Dosage
Three steps convert any vial and BAC water combination into the exact volume to draw on a U-100 insulin syringe.
Step 1 — Calculate concentration (mg/mL)
Divide the total peptide in the vial (mg) by the volume of BAC water you added (mL). For example: a 5 mg Tirzepatide vial reconstituted with 2 mL BAC water gives 5 ÷ 2 = 2.5 mg/mL.Step 2 — Calculate draw volume (mL)
Divide your target dose (mg) by the concentration (mg/mL). For a 0.5 mg dose at 2.5 mg/mL: 0.5 ÷ 2.5 = 0.2 mL. This is the exact volume to draw into the syringe.Step 3 — Convert to U-100 syringe units
Multiply the draw volume (mL) by 100. For 0.2 mL: 0.2 × 100 = 20 U-100 units. Read this number on the unit markings of a standard insulin syringe.
Dosage Formula
Concentration formula
Concentration (mg/mL) = Vial mg ÷ BAC water mLDraw volume formula
Draw volume (mL) = Dose (mg) ÷ Concentration (mg/mL)U-100 syringe units
U-100 units = Draw volume (mL) × 100These three formulas apply to any Tirzepatide vial, regardless of size. U-100 is the standard insulin-syringe scale: 100 units = 1 mL.
Example Tirzepatide Calculations
Step-by-step worked examples using common vial sizes. Results are for illustrating the math only.
Example
10 mg vial + 2 mL BAC water, 5 mg dose
Given
- Vial
- 10 mg
- BAC water
- 2 mL
- Target dose
- 5 mg
Result
100 units
1 mL at 5 mg/mL
- Concentration: 10 ÷ 2 = 5 mg/mL
- Draw volume: 5 ÷ 5 = 1 mL
- U-100 units: 1 × 100 = 100 units
Example
10 mg vial + 2 mL BAC water, 2.5 mg dose
Given
- Vial
- 10 mg
- BAC water
- 2 mL
- Target dose
- 2.5 mg
Result
50 units
0.5 mL at 5 mg/mL
- Concentration: 10 ÷ 2 = 5 mg/mL
- Draw volume: 2.5 ÷ 5 = 0.5 mL
- U-100 units: 0.5 × 100 = 50 units
Example Tirzepatide Dosage Table
Common vial and BAC water combinations with calculated concentration, draw volume, and U-100 syringe units. For education only — verify your vial label before use.
| Vial (mg) | BAC water (mL) | Concentration | Dose (mg) | Draw (mL) | U-100 units |
|---|---|---|---|---|---|
| 10 mg | 2 mL | 5 mg/mL | 2.5 mg | 0.5 mL | 50 units |
| 10 mg | 2 mL | 5 mg/mL | 5 mg | 1 mL | 100 units |
| 20 mg | 2 mL | 10 mg/mL | 5 mg | 0.5 mL | 50 units |
| 20 mg | 5 mL | 4 mg/mL | 5 mg | 1.25 mL | 125 units |
Tirzepatide Reconstitution Guide
Tirzepatide research vials are supplied as lyophilised powder. Reconstitute with bacteriostatic water:
- Swab stoppers with alcohol.
- Inject BAC water slowly along the vial wall.
- Gently swirl until dissolved. Do not shake vigorously.
- Inspect for clarity — solution should be clear to slightly yellow.
- Store refrigerated. Use within labelled window.
Tirzepatide is a dual GLP-1/GIP receptor agonist. Approved versions (Mounjaro, Zepbound) come pre-filled; research vials require reconstitution math like any other lyophilised peptide.
Important
For educational and research purposes only. Not medical advice. Consult a licensed healthcare professional before making any medical or health-related decisions.
Frequently Asked Questions
How do I calculate tirzepatide draw volume?
Divide your dose (mg) by the concentration (mg/mL). For a 10 mg vial + 2 mL BAC: 5 mg/mL. For a 5 mg dose: 5 ÷ 5 = 1.0 mL = 100 U-100 units.
What are U-100 syringe units?
U-100 is the standard scale for insulin syringes. 100 units = 1.0 mL. That means 10 units = 0.1 mL, 50 units = 0.5 mL. Multiply any draw volume in mL by 100 to get the U-100 units reading.
Do I need to recalculate if I change the amount of BAC water?
Yes. Changing BAC water volume changes the concentration (mg/mL), which changes the draw volume for the same mg dose. Always recalculate using: concentration = vial mg ÷ BAC water mL, then draw volume = dose mg ÷ concentration.
What is tirzepatide?
Tirzepatide is a dual GLP-1 and GIP receptor agonist studied and approved (under the names Mounjaro and Zepbound) for type 2 diabetes and obesity. This calculator covers reconstitution math only — it is not medical advice.
Sources & references
Dose steps come from the FDA prescribing information for Mounjaro and Zepbound. The vial tables are reconstitution math only: they turn a vial size, a BAC water volume and a dose into mL and U-100 units. They don't recommend a dose.
- Mounjaro (tirzepatide) injection: US Prescribing Information (FDA, revised 01/2026)Section 2.1: start at 2.5 mg once weekly; after 4 weeks, 5 mg; increase in 2.5 mg steps after at least 4 weeks on the current dose; maximum 15 mg once weekly in adults.
- Zepbound (tirzepatide) injection: US Prescribing Information (FDA, revised 02/2026)Sections 2.1-2.2: same 2.5 mg start and 2.5 mg steps; maintenance 5, 10 or 15 mg once weekly; maximum 15 mg once weekly.
Updated October 17, 2026