Tirzepatide dosage in units

Tirzepatide dose-to-units table (all doses × common concentrations)

On a U-100 insulin syringe (1 mL = 100 units), this is what each labeled tirzepatide dose works out to at the concentrations compounded vials are commonly dispensed at. Read the concentration off your own vial first, then read down that column.

Every cell is units on a U-100 syringe. The columns are concentrations, not one right answer — the whole point is that the number moves with your vial.

The math, so you can check any dose yourself

A U-100 insulin syringe holds 1 mL across 100 units, so 1 unit is 0.01 mL. Because the drug amount in each mL is the concentration, the conversion is:

Worked, at 10 mg/mL: 5 mg ÷ 10 mg/mL = 0.500 mL, and 0.500 mL × 100 = 50 units. Change the concentration to 5 mg/mL and the same 5 mg becomes 100 units — double the volume, same dose. That is the error this page exists to prevent.

This is not hypothetical — the FDA has counted the overdoses

The FDA issued a safety alert about dosing errors with compounded injectable GLP-1s and named the cause directly: “confusion between different units of measurement (milliliters, milligrams and units)” combined with people being unfamiliar with drawing from a vial. In the reported cases, patients withdrew more than prescribed — in some instances 5 to 20 times the intended dose, with adverse events including vomiting, dehydration, gallstones and acute pancreatitis, some requiring hospitalization. As of April 2025 the agency had roughly 480 reports for compounded tirzepatide and 520 for compounded semaglutide. The single question this page answers — how many units — is the exact step where those errors happen.

If you take brand Mounjaro or Zepbound, you do not need this at all

This whole question only exists for compounded tirzepatide drawn from a multi-dose vial. FDA-approved Mounjaro and Zepbound come in fixed single-dose pens (and, for Zepbound, single-dose vials) at the labeled milligram dose — 2.5, 5, 7.5, 10, 12.5 and 15 mg. There is no syringe to draw, no concentration to read, and no unit conversion to get wrong. If cost is what pushed you toward a compounded vial and a syringe, the Zepbound savings routes and compounded cost comparison are worth a look first — the brand pen removes the dosing-math risk entirely.

Before you draw a compounded dose

• Confirm the concentration on your actual vial.Not a chart, not last month's vial, not the number a forum gave you — the mg/mL on the label in your hand.
• Use the syringe your pharmacy specified, and confirm it is U-100. The tables here assume a U-100 insulin syringe (the human-medicine standard). A U-40 syringe — sold for pet insulin — is marked differently and would throw the volume off by 2.5×.
• If your vial was shipped as powder, the concentration depends on how much bacteriostatic water was added to reconstitute it — follow the exact reconstitution instructions, because getting that wrong changes every dose after it.
• A single injection above ~50 units (0.5 mL) is unusual for compounded tirzepatide and is a common sign the concentration was entered wrong. If your math lands there, stop and re-check.
• Never change your prescribed dose to hit a round number of units. The dose is the milligrams your prescriber set; the units are just how you measure it.

Sources

• FDA — Concerns with Unapproved GLP-1 Drugs Used for Weight Loss (dosing-error reports, units/mg/mL confusion)
• University of Illinois Chicago Drug Information Group — Safety concerns regarding compounded GLP-1 receptor agonists (August 2025)
• Zepbound (tirzepatide) prescribing information — the FDA-approved labeled dose ladder (2.5–15 mg), no unit conversion required

Answer for a specific dose