All compound calculators / Tirzepatide
01Free · No signup · Runs in your browser
Tirzepatide reconstitution calculator
Enter how much Tirzepatide is in your vial and how much bacteriostatic water you added. The calculator works out the concentration, and converts whatever amount you type into units on a U-100 insulin syringe. It converts what you enter — it does not suggest, recommend or validate any amount.
02About Tirzepatide
TirzepatideGLP-1 / GIP
A dual GLP-1 and GIP receptor agonist, and a prescription medicine in the United States and the EU.
Tirzepatide reaches people two ways and only one of them concerns this page. Research vials hold a lyophilised powder — 5, 10, 15 and 30 mg are the sizes most commonly listed — and have to be reconstituted before anything can be drawn from them. Prescription products are ready-made solutions in pens, already at a fixed concentration, and are never reconstituted.
The vial range is wider here than for most compounds on this site: a 30 mg vial holds six times what a 5 mg vial holds. Read a number of syringe units off one vial and it means something entirely different on the other, which is why the vial field above is the first thing to set and the last thing to assume.
03Reading the units for Tirzepatide
Reading the units for Tirzepatide
- Both ends are conventionally written in milligrams for tirzepatide — what is printed on the vial and what is typed into the amount field — where most research peptides on this site are written in micrograms at the amount end. Check the mcg/mg switch before reading the result; the two are a factor of 1000 apart.
- There is no International Unit for tirzepatide. An IU is defined per substance against a reference standard, and no such standard exists here, so the IU option in the amount field does not apply. It is on the page for compounds that do have one.
- At this page's 2 mL starting volume the four example vials give 2.5, 5, 7.5 and 15 mg/mL. One unit on a U-100 syringe is 0.01 mL, so a unit off those vials carries 25, 50, 75 and 150 mcg respectively. Change the water volume and every one of those figures changes; what is in the vial does not.
04Handling and storage
Handling and storage
- Before it is mixed, a lyophilised peptide is a dry powder, and dry powder is the stable form. Once bacteriostatic water goes in, the clock starts — the solution is what degrades, not the powder.
- Add the water down the side of the vial and let it dissolve rather than shaking it. Peptides are large, fragile molecules; foaming is the visible sign that you were rough with one.
- Heat, light and freeze-thaw cycles are what shorten a reconstituted vial's life. Follow the storage and expiry guidance from your supplier or your clinician — this page cannot tell you how long your vial is good for.
- A reconstituted GLP-1 solution is kept cold and out of the light. Cold storage is not the hazard — freezing and thawing a reconstituted vial is, and so is leaving it somewhere warm between uses.
05Questions
Questions
How much bacteriostatic water should I add to a Tirzepatide vial?
That is your choice, and it changes only the concentration — never the total amount in the vial. More water spreads the same powder across more units on the syringe, which makes small amounts easier to read; less water means fewer units. Type your vial size and your water volume above and the calculator shows the concentration you would end up with.
How do I read the result in units?
A U-100 insulin syringe is marked in units, where 100 units is 1 mL. The calculator converts the amount you entered into millilitres first, then into those units, so the number it shows is the mark to draw to on that syringe. Check that the syringe in your hand is actually U-100 — U-40 syringes exist and the markings mean something different.
Does Tirzepatide need to be reconstituted?
Only if you have it as a lyophilised powder. Powder has to be dissolved in bacteriostatic water before anything can be drawn from it. Anything already supplied as a solution does not get reconstituted, and this calculator is not the right tool for it.
Is this calculator free?
Yes. The reconstitution calculator on pepcoreapp.com stays free in any browser, with no signup, and it runs entirely on your device. The PepCore iPhone app is a separate subscription — $6.99/month or $39.99/year, with a 7-day free trial.
Can I enter tirzepatide in IU?
No, and the IU switch will not give you a meaningful answer for it. An International Unit is defined per substance against an agreed reference standard; tirzepatide has no such standard, so there is no conversion between IU and milligrams to apply. Leave the amount switch on mg or mcg. The IU option exists on this page for compounds that do have a defined unit.
Why does the same number of units mean a different amount on a 5 mg and a 30 mg vial?
Because the syringe measures volume, not weight. A unit on a U-100 syringe is always 0.01 mL — the amount of tirzepatide inside that 0.01 mL is whatever the concentration happens to be. Put 2 mL of water into a 5 mg vial and you have 2.5 mg/mL; put the same 2 mL into a 30 mg vial and you have 15 mg/mL, six times as much in an identical volume. That is the commonest source of error with a compound sold across this wide a vial range.
Stop redoing this math every vial
PepCore for iPhone saves the reconstitution per vial, tracks what is open and what expires when, logs every dose, and rotates injection sites on a body map. No account, no sign-in — your data stays on your device. Subscription with a 7-day free trial.