Tirzepatide Reconstitution Calculator: Dose & Syringe Units

Worked examples

30 mg vial, 2 mL water, 2.5 mg dose

Concentration = 30 ÷ 2 = 15 mg/mL. Volume = 2.5 ÷ 15 = 0.167 mL ≈ 16.7 units on a U-100 syringe. About 12 doses per vial.

10 mg vial, 1 mL water, 2.5 mg dose

Concentration = 10 ÷ 1 = 10 mg/mL. Volume = 2.5 ÷ 10 = 0.25 mL = 25 units. About 4 doses per vial.

60 mg vial, 3 mL water, 5 mg dose

Concentration = 60 ÷ 3 = 20 mg/mL. Volume = 5 ÷ 20 = 0.25 mL = 25 units. About 12 doses per vial.

Picking a round unit count

A 30 mg vial in 3 mL gives 10 mg/mL, so a 2.5 mg dose is exactly 25 units. Choosing the water volume to hit a whole number makes dosing far easier to read.

Reconstituting tirzepatide, step by step

Tirzepatide is a dual GIP and GLP-1 receptor agonist. Compounded and research-grade vials arrive as a freeze-dried (lyophilized) powder that has to be reconstituted with bacteriostatic water before any dose can be measured. The arithmetic is the same as for any peptide, but tirzepatide has one quirk: doses are usually written in whole milligrams rather than micrograms, so the numbers are larger.

The three steps

Concentration = vial (mg) ÷ water (mL). A 30 mg vial in 2 mL of bacteriostatic water is 15 mg/mL.
Volume = dose (mg) ÷ concentration (mg/mL). A 2.5 mg dose at 15 mg/mL is 2.5 ÷ 15 = 0.167 mL.
Units = volume (mL) × 100. 0.167 mL is about 16.7 units on a U-100 insulin syringe.

Why the water volume matters here

Because tirzepatide doses step up over time (a common pattern is 2.5 mg, then 5 mg, then higher), it helps to choose a water volume that keeps each dose on a clean, readable unit count as you titrate. Reconstituting a 30 mg vial in 3 mL gives 10 mg/mL, which turns a 2.5 mg dose into exactly 25 units and a 5 mg dose into 50 units. The calculator recalculates instantly, so you can try a few water volumes before you mix.

Doses per vial

Divide the vial size by your dose to see how long it lasts: a 30 mg vial at 2.5 mg per dose is 12 doses. The water you add does not change that count, only the units you draw each time.

Important safety note

Tirzepatide is a prescription medication, and research-grade or compounded vials are not approved for human use. This calculator only performs reconstitution arithmetic; it does not recommend a dose, a titration plan, or whether tirzepatide is suitable for you, and it cannot judge what is safe. Treat every result as an educational estimate, not medical advice. Verify the amount on your vial label, talk to a licensed medical professional before acting, and follow all applicable laws.

Frequently asked questions

How do I reconstitute a tirzepatide vial?

Add bacteriostatic water to the freeze-dried powder, then work out the concentration by dividing the milligrams in the vial by the millilitres of water. Divide your target dose by that concentration to get the volume, and multiply by 100 for units on a U-100 insulin syringe. The calculator does all three steps and shows the fill line.

How much water do I add to tirzepatide?

The water volume is your choice and only sets the concentration, not the dose. Because tirzepatide vials are often 10–60 mg and doses are measured in whole milligrams, many people add 2–3 mL so the resulting units land on round numbers. Enter different water volumes above and watch how the unit count changes.

Why are tirzepatide units different from semaglutide units?

Tirzepatide doses are usually measured in milligrams while many peptides are dosed in micrograms, so the numbers look larger. The math is identical; only the concentration and dose values differ. Always read the amount off your own vial rather than assuming a standard.

Is this tirzepatide calculator medical advice?

No. It is a reconstitution math tool only. It does not recommend a dose, a titration schedule, or whether tirzepatide is appropriate for you. Tirzepatide is a prescription medicine; research-grade vials are not approved for human use. Talk to a licensed medical professional and follow the laws that apply to your product.