Tool
Tirzepatide dosage calculator
Enter a tirzepatide vial's mg amount, the diluent you added, and a dose - get the concentration, the volume to draw, and insulin-syringe units. Arithmetic only; it does not know your dose or your vial.
Guides:tirzepatide dosage (FDA schedule)·tirzepatide overview
Your vial
Printed on the vial. There is no standard size - enter what yours says.
This changes how much you draw - never how many doses the vial holds.
100 units per mL. 1 unit = 0.01 mL. This is what almost every insulin syringe sold is, in every barrel size.
Capacity only. A 1 mL U-100 syringe holds 100 units - the scale decides that, not the barrel.
Draw this much
= 0.5 mL on a 1 mL U-100 syringe
- Concentration
- 5,000 mcg/mL
- Exact volume
- 0.5 mL
- Dose you actually get
- 2,500 mcg
- Doses per vial(unaffected by water volume)
- 4
The 10 mg vial / 2.5 mg dose shown above is only an example to demonstrate the arithmetic (2.5 mg is the FDA-approved starting dose for the approved pens) - it is not a recommendation. Replace every field with your own vial's actual numbers. Results update in the address bar so a calculation is shareable; nothing is stored.
The actual tirzepatide dose
The only dosing schedule that has gone through FDA review starts at 2.5 mg once weekly for four weeks, then rises in 2.5 mg steps no sooner than every four weeks, up to a 15 mg maximum. The 2.5 mg starting dose is not a maintenance dose; on the Zepbound label, maintenance doses are 5 mg, 10 mg or 15 mg once weekly. That schedule, the missed-dose rule, and what changes with a compounded vial are laid out in full on thetirzepatide dosage page. Background on the drug itself - mechanism, approval, boxed warning - is on themain tirzepatide page.
This calculator answers a different question: once you know a dose in mg, how much volume does that come to in a given vial, and how many syringe units is that. It does not set the dose itself.
Common questions
Is this the FDA-approved tirzepatide dose?
The 2.5 mg starting dose preset here is the FDA-approved starting dose for Mounjaro and Zepbound. This calculator itself does not know your dose - it only converts a vial size, diluent volume, and dose into a volume to draw and syringe units. See the tirzepatide dosage page for the full approved titration schedule.
Does this calculator work for a compounded tirzepatide vial?
It will do the arithmetic for any vial size and diluent volume you type in. It has no way to verify what is actually in a compounded vial, and FDA has documented dosing errors specifically in the compounded tirzepatide supply. A compounded vial has not gone through the review that set the approved schedule.
What is a common tirzepatide vial size?
Vial sizes vary by supplier and are not standardized the way the approved pen doses are. The 10 mg example preset on this page is only a starting point to show the arithmetic - type in the actual mg amount printed on your own vial label before drawing anything.
How much tirzepatide do I draw for 2.5 mg?
That depends entirely on the concentration after reconstitution, which depends on the vial size and how much diluent was added - there is no single answer. Enter the vial's mg amount and diluent volume into the calculator above and it works out the volume and syringe units for whatever dose you enter.
Can I use an insulin syringe for tirzepatide?
People commonly measure small-volume injections with insulin syringes marked in units, which is what the syringe-scale option in this calculator converts to. A U-100 syringe is 100 units per mL regardless of barrel size (0.3, 0.5 or 1 mL) - see the peptide calculator page for why "U-50" is not a real scale.
Is this medical advice?
No. It performs arithmetic on numbers you type - it does not know what is in your vial, whether a dose is appropriate, or whether you should be using tirzepatide at all. Follow your prescriber and the product label for an approved pen; a compounded or research vial carries none of that review.