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Tirzepatide Dosage Calculator (mg to Units)

Enter the tirzepatide dose your clinician prescribed and the strength printed on your compounded vial. The page works out the concentration, the milliliters to draw and the matching units on a U-100 insulin syringe, with the arithmetic shown so you and your pharmacy can check it.

  • Calculator
  • About 3 min
  • Dose volume arithmetic (Boyer 2016)
  • Runs in your browser, nothing is sent
  • Medical review: Medical review pending
Open the calculator

What this calculator works out

Compounded tirzepatide usually arrives as a multi-dose vial labeled in milligrams per milliliter, while the prescription is written in milligrams. Three small steps connect the two, and every one of them is printed on the result so nothing is hidden.

  1. 1

    Concentration of your vial

    Milligrams in the vial divided by its milliliters, in mg/mL. Some labels print the concentration directly; others print the total milligrams and the fill volume. Either way, this is the number the rest of the arithmetic depends on.

  2. 2

    Volume to draw

    The prescribed milligrams divided by the concentration, in milliliters. Shown to three decimal places so you can see when a dose lands between syringe markings rather than exactly on one.

  3. 3

    Units on a U-100 syringe

    On a U-100 insulin syringe, 1 mL is 100 units and every unit is 0.01 mL. The page multiplies the volume by 100 and tells you which syringe size the dose fits, so a 0.25 mL draw reads as 25 units.

How this compares with a typical online quiz

FeatureTypical free quizRegenerated.com
Arithmetic shown step by stepRarelyConcentration, volume and units, each printed
Takes the vial strength you actually haveOften a fixed concentrationAny mg and mL from your label
Suggests a doseOften, as a 'typical' ladderNever; the prescription is the only dose it takes
Flags doses too small or too large to drawNoYes, under 5 units and over 100 units
Regulatory status explainedRarelyBrand approvals and the compounding rules, with each FDA page's date
Answers sent to a serverOftenNever; scored in your browser, counts-only events

The labeled tirzepatide ladder, as information only

Tirzepatide is sold by Eli Lilly as Mounjaro, approved by the FDA in May 2022 for adults with type 2 diabetes, and as Zepbound, approved in November 2023 for chronic weight management in adults with obesity, or with overweight plus a weight-related condition, and in December 2024 for moderate to severe obstructive sleep apnea in adults with obesity. Both labels describe the same once-weekly subcutaneous ladder: the first step is 2.5 mg once weekly for four weeks, then 5 mg, with any further increase of 2.5 mg made only after at least four weeks on the current step, up to a maximum of 15 mg once weekly. The six labeled steps are therefore 2.5, 5, 7.5, 10, 12.5 and 15 mg.

That ladder is printed here so you can recognize where a prescription sits, not so you can pick a rung. Clinicians move patients up, hold them, or move them down based on tolerance, weight change and side effects, and some prescribe amounts between the labeled steps. The calculator takes exactly one dose: the one written on your prescription. If the number you plan to enter is not the number your clinician wrote, the page is the wrong tool and a phone call to the clinic is the right one.

Compounded vials versus brand pens and vials

Brand tirzepatide comes as single-dose pens and single-dose vials, each holding one full dose in 0.5 mL. With those there is nothing to calculate: the pen delivers the whole dose, and a single-dose vial is drawn up in full. This page exists for compounded tirzepatide, which pharmacies dispense as a multi-dose vial labeled in mg/mL, where the patient draws a prescribed fraction each week with an insulin syringe.

Compounded copies of a brand drug are permitted by the FDA only while that drug is on the official shortage list. Tirzepatide was placed on the list in December 2022 and the FDA declared the shortage resolved on December 19, 2024, which ended the shortage-based allowance for compounded copies after transition deadlines in February and March 2025. The FDA's page for compounders, current as of April 1, 2026 and checked on October 8, 2026, states that tirzepatide appears neither on the 503B bulks list nor on the drug shortage list, and on April 30, 2026 the agency proposed to exclude semaglutide, tirzepatide and liraglutide from the 503B bulks list, finding no clinical need for outsourcing facilities to compound them from bulk. That is a proposal, with comments taken to June 29, 2026, and not a final rule; as of October 8, 2026 the FDA had not issued a final determination. What is left is narrow and patient-specific, such as a prescriber's documented determination that a compounded product has a significant difference from the commercially available one for an identified individual patient. Whether a given vial qualifies does not follow from the lists alone, so ask the pharmacy on what basis yours was compounded. Keep the label, because the concentration on it is the only concentration this calculator should ever be given.

Reading a U-100 insulin syringe

A U-100 syringe is marked for insulin at 100 units per milliliter, and because compounded tirzepatide is drawn with the same syringes, the markings double as a volume scale: 100 units is 1.0 mL, 50 units is 0.5 mL, 10 units is 0.1 mL and 1 unit is 0.01 mL. Syringes come in 0.3 mL (30 unit), 0.5 mL (50 unit) and 1 mL (100 unit) sizes. The 0.3 mL size is usually marked in half units and the 1 mL size in two-unit steps, so a dose that reads as 25 units is easier to measure accurately in a 0.3 mL syringe than in a 1 mL one.

If the page gives a fractional number such as 37.5 units, the honest answer is that the dose lands between marks. Do not round on your own. The pharmacy can dispense a concentration that gives a whole number, or the clinic can tell you which direction to round and why. Small doses magnify this: at 2 units, a half-unit misread is a 25 percent error in the dose.

What the trials showed, and the 5 percent marker

In SURMOUNT-1, a 72-week trial in adults with obesity and no diabetes, mean weight change was 15.0 percent on 5 mg, 19.5 percent on 10 mg and 20.9 percent on 15 mg, against 3.1 percent on placebo, all alongside a lifestyle program. In SURPASS-2, in adults with type 2 diabetes, tirzepatide at 5, 10 and 15 mg lowered HbA1c and weight more than semaglutide 1 mg over 40 weeks. The most common adverse effects in both trials were gastrointestinal: nausea, diarrhea, vomiting and constipation, mostly during dose increases.

The 2013 AHA/ACC/TOS obesity guideline treats a sustained loss of 5 percent of starting weight as the point where blood pressure, glucose and lipid benefits become reliably measurable, and the FDA uses a 5 percent placebo-adjusted difference as one benchmark for weight-management drugs. That marker is useful for judging whether a prescribed dose is doing its job over months; it is not a reason to change a dose yourself. The label also carries a boxed warning about thyroid C-cell tumors seen in rodents, with the drug contraindicated in anyone with a personal or family history of medullary thyroid carcinoma or MEN 2, and it warns about pancreatitis, gallbladder disease, dehydration-related kidney injury, delayed stomach emptying and low blood sugar when combined with insulin or sulfonylureas.

Methodology and sources

The calculator applies the dimensional analysis taught in nursing dosage texts, here as set out in Boyer's Math for Nurses (9th edition, Wolters Kluwer, 2016): concentration equals the milligrams in the vial divided by its milliliters; the volume to draw equals the prescribed milligrams divided by that concentration; and units on a U-100 insulin syringe equal milliliters times 100, because that syringe is calibrated at 100 units per milliliter. No clinical judgment is involved at any step. The dose comes from the prescriber, the strength comes from the pharmacy label, and the page only connects them. It is written for compounded multi-dose vials; brand single-dose pens and vials deliver the whole dose and need no calculation.

Worked example: a prescription of 5 mg from a vial labeled 50 mg in 5 mL. The concentration is 50 / 5 = 10 mg/mL. The volume is 5 / 10 = 0.5 mL. On a U-100 syringe that is 0.5 x 100 = 50 units. The same steps give the registry's own example: 100 mg prescribed from a vial holding 2000 mg in 10 mL (200 mg/mL) is 100 / 200 = 0.5 mL, which is 50 units. A 2.5 mg dose from a 10 mg/mL vial is 0.25 mL, or 25 units; a 15 mg dose from the same vial is 1.5 mL, or 150 units, which no single insulin syringe holds, and the page says so.

Three limits matter. First, the page cannot tell whether the label is in mg/mL or total mg per vial, so read it carefully: a vial marked 10 mg/mL in 2.5 mL holds 25 mg total. Second, it assumes the whole vial is uniformly mixed, which is true of a solution but is why the concentration is written on the label rather than measured at home. Third, it flags doses under 5 units and over 100 units because both are hard to draw accurately, but it cannot know whether such a dose is intended. The labeled ladder (2.5 to 15 mg) and the trial results in the sections above come from the Zepbound prescribing information and the SURMOUNT-1 and SURPASS-2 papers; they are context, not a dose.

Medical review: Medical review pending. Last updated .

References

  1. Boyer MJ. Math for Nurses: A Pocket Guide to Dosage Calculation and Drug Preparation. 9th ed. Philadelphia: Wolters Kluwer; 2016.
  2. Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med. 2022;387(3):205-216. doi:10.1056/NEJMoa2206038
  3. Frias JP, Davies MJ, Rosenstock J, et al. Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes. N Engl J Med. 2021;385(6):503-515. doi:10.1056/NEJMoa2107519
  4. Eli Lilly and Company. Zepbound (tirzepatide) injection, for subcutaneous use: prescribing information. Indianapolis, IN; revised 2024. https://pi.lilly.com/us/zepbound-uspi.pdf
  5. Jensen MD, Ryan DH, Apovian CM, et al. 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults. Circulation. 2014;129(25 Suppl 2):S102-S138. doi:10.1161/01.cir.0000437739.71477.ee
  6. US Food and Drug Administration. FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize (content current as of April 1, 2026) and FDA proposes to exclude semaglutide, tirzepatide and liraglutide on the 503B bulks list (April 30, 2026). Checked October 8, 2026. https://www.fda.gov/drugs/drug-alerts-and-statements/fda-clarifies-policies-compounders-national-glp-1-supply-begins-stabilize and https://www.fda.gov/news-events/press-announcements/fda-proposes-exclude-semaglutide-tirzepatide-and-liraglutide-503b-bulks-list

Tirzepatide Dosage Calculator (mg to Units) FAQ

Enter the mg/mL figure as the vial milligrams and 1 as the vial milliliters. A label that reads 10 mg/mL becomes 10 mg in 1 mL, and the concentration the page prints will match the label. If the label gives a total, such as 25 mg in 2.5 mL, enter those two numbers as they are.

No, and it does not need to. Brand pens and single-dose vials contain one full dose in 0.5 mL, so the device or the whole vial is the dose. This page is for compounded multi-dose vials labeled in mg/mL, where a fraction of the vial is drawn each week.

Do not round it yourself. A fractional result means the prescribed dose lands between syringe markings at this concentration. The pharmacy can dispense a concentration that gives a whole number, or the prescribing clinic can tell you which way to round and confirm the dose is still what they intend.

Because the dose is a medical decision that depends on your history, your tolerance and your response, and because tirzepatide carries a boxed warning and several serious cautions. The labeled ladder from 2.5 to 15 mg is printed on this page as information, with its source, and nothing on the page is a dose for you to use.

Not necessarily. Compounded drugs are not FDA-approved and are not tested for safety or effectiveness before dispensing; the FDA has reported adverse events linked to dosing errors with compounded GLP-1 products, often from confusion between units, milliliters and milligrams. Use the concentration on your own label, and if anything on the label is unclear, call the pharmacy before drawing a dose.

Yes. Your answers and the numbers you enter are scored in your browser and are never sent to us. They stay in this browser tab so you can return to your result, and closing the tab clears them. The only thing the page sends us is a counts-only event: which test was started or completed, the result band and the headline number, with no answers, no entered values and no account. There is nothing to sign up for.

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Important: This calculator is arithmetic on a dose your clinician prescribed and the strength printed on your vial. It is not a prescription, not a dose suggestion, not a diagnosis and not a recommendation for or against tirzepatide. Compounded medicines are not FDA-approved; confirm the concentration with your pharmacy and the dose with your prescriber before drawing anything. If your symptoms are severe or sudden, seek urgent medical care.