How to Use This Calculator
Enter the milligrams of tirzepatide in the vial, then the bacteriostatic water added in mL. Enter the dose in milligrams and pick the syringe size, then click Calculate. The result shows the concentration, the draw in mL and units, and how many doses of that size the vial holds.
Why Tirzepatide Is Entered in Milligrams
Tirzepatide is handled in whole milligrams rather than the micrograms used for smaller peptides, so the dose field on this page is in mg. A 2.5 mg dose is 2,500 mcg. Enter the figure in milligrams and the calculator does the rest.
Tirzepatide Bac Water Calculator: Draw Volume at Different Water Volumes
The table shows the math for a 20 mg tirzepatide vial. The draw column uses a 2.5 mg dose only because it is the worked example on this page. Change the numbers in the calculator above to match your own vial and dose.
| Bac water added | Concentration | Draw for 2.5 mg | Units |
|---|---|---|---|
| 1 mL | 20 mg/mL | 0.125 mL | 12.5 units |
| 2 mL | 10 mg/mL | 0.25 mL | 25 units |
| 3 mL | 6.67 mg/mL | 0.375 mL | 37.5 units |
More water gives a lower concentration and a longer draw, while the number of doses stays at 20 / 2.5 = 8 in every row. For semaglutide, use the Semaglutide Dose Calculator.
Tirzepatide Vial Sizes: 10 mg, 20 mg, 30 mg and 60 mg at 2 mL
The concentration depends on the vial size. The table keeps the water at 2 mL and the dose at 2.5 mg, so you can see how the vial size changes the draw and the dose count.
| Vial size | Concentration at 2 mL | Draw for 2.5 mg | Doses per vial |
|---|---|---|---|
| 10 mg | 5 mg/mL | 0.5 mL (50 units) | 4 |
| 20 mg | 10 mg/mL | 0.25 mL (25 units) | 8 |
| 30 mg | 15 mg/mL | 0.167 mL (16.7 units) | 12 |
| 60 mg | 30 mg/mL | 0.083 mL (8.3 units) | 24 |
Doses per vial is the vial mg divided by the dose in mg, rounded down. A larger vial in the same water is more concentrated, so the same dose is a smaller draw.
This Page Covers Tirzepatide Only
For semaglutide, or for a vial that is sized against both compounds together, use the Semaglutide and Tirzepatide Calculator. This page keeps the wording and the example for a single tirzepatide vial.
Who Should Use This
Researchers working with a single tirzepatide vial who need the syringe draw for a given dose in milligrams and the number of doses the vial holds.
What This Calculator Does
The Tirzepatide Calculator turns the milligrams of tirzepatide in a vial, the bacteriostatic water added and a dose in milligrams into the concentration, the draw in mL and units on a U-100 syringe, and the number of doses the vial holds.
Formula Used
Concentration (mg/mL) = Tirzepatide (mg) / BAC water (mL)Draw (mL) = Dose (mg) / ConcentrationUnits to draw = Draw (mL) x 100 (U-100 syringe)Doses per vial = FLOOR(Tirzepatide (mg) / Dose (mg))Example Calculation
Limitations
This is a unit-conversion tool, not guidance on what to use. It assumes the vial dissolves evenly and that the vial size on the label is accurate, and it ignores dead space and draw loss. Tirzepatide is a prescription medicine in many places; this page does no more than convert the figures you enter. Confirm the vial contents against the supplier label before entering them.
Frequently Asked Questions
How many units is 2.5 mg of tirzepatide?
It depends on the concentration. In a 20 mg vial reconstituted with 2 mL of bacteriostatic water the concentration is 10.00 mg/mL, so 2.5 mg is 0.250 mL, which is 25.0 units on a U-100 syringe. Change the vial size or the water volume and the units change with it.
How do I work out the concentration of a tirzepatide vial?
Divide the milligrams of tirzepatide in the vial by the millilitres of bacteriostatic water you added. A 20 mg vial with 2 mL of water is 10.00 mg/mL. A 10 mg vial with the same 2 mL is 5.00 mg/mL.
Why is the dose in milligrams and not micrograms?
Tirzepatide is handled in whole milligrams, unlike the smaller peptides that are measured in micrograms. A 2.5 mg dose is the same as 2,500 mcg; entering it in milligrams keeps the figures simple.
Does this calculator cover semaglutide too?
No. This page is for a single tirzepatide vial. For semaglutide, or for a vial sized against both compounds, use the Semaglutide and Tirzepatide Calculator.
How much bac water do I add to a tirzepatide vial?
The water volume only sets the concentration, so the calculator works with any amount. For a 20 mg vial, 1 mL gives 20 mg per mL, 2 mL gives 10 mg per mL and 3 mL gives 6.67 mg per mL. Divide the dose in mg by the mg per mL to get the draw in mL, then multiply by 100 for units. Enter your own vial size and water volume to see the draw. This is arithmetic only, not a recommended amount.
Does this tirzepatide dosage calculator work for compounded tirzepatide vials?
It does the same arithmetic for any vial: you enter the mg in the vial, the bac water you added and the dose in mg. Use the figures printed on your vial or in the instructions that came with it, because the calculator cannot check what is in a vial or confirm a concentration. It gives no medical advice, so ask your prescriber or pharmacist about the dose itself.