Evidence review

Tirzepatide Dosage Chart: mg to Units, Every Dose

The short answer

Zepbound starts at 2.5 mg once a week for four weeks, then rises in 2.5 mg steps, each held at least four weeks, through 5, 7.5, 10 and 12.5 mg to a 15 mg maximum. A brand single-dose vial holds every dose in 0.5 mL, which is 50 units. For compounded vials, units equal mg divided by mg/mL, times 100.

By The WeighLab Bench, Tools & Data DeskOctober 2026

Section index05

Tirzepatide is dosed in milligrams, but if you draw it from a vial, the syringe in your hand is marked in units. This page puts the whole picture in three tables: every labeled tirzepatide dose and when it starts, what each dose looks like in a brand-name Zepbound vial, and how many units each dose is in a compounded vial at a few common concentrations. For how long to stay on each dose and how it compares with Wegovy's schedule, see the Zepbound and Wegovy titration schedule.

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What is the tirzepatide dosage schedule?

Every dose below comes from the Zepbound prescribing information. Treatment starts at 2.5 mg once weekly for 4 weeks, which the label calls a starting dose only, not a maintenance dose. After that, the dose can go up in 2.5 mg steps, with at least 4 weeks on each dose before the next increase¹. The weeks column shows the fastest pace the label allows; many people and prescribers move more slowly, and the label tells prescribers to weigh response and tolerability when picking a maintenance dose.

Step	Weekly dose	Earliest weeks on this dose	What the label says about it
1	2.5 mg	Weeks 1–4	Starting dose only, not a maintenance dose
2	5 mg	Weeks 5–8	A maintenance dose for weight reduction
3	7.5 mg	Weeks 9–12	A step on the way up
4	10 mg	Weeks 13–16	A maintenance dose for weight reduction and for sleep apnea
5	12.5 mg	Weeks 17–20	A step on the way up
6	15 mg	Week 21 onward	A maintenance dose, and the labeled maximum

The same molecule and the same dose steps are sold for type 2 diabetes as Mounjaro; Mounjaro vs Zepbound covers why the price differs.

How many units is each Zepbound dose from a vial?

Brand-name Zepbound comes in a single-dose pen, single-dose vials, multi-dose vials and a KwikPen. Pens measure the dose for you. Vials don't, and the label tells vial users to use a 1 mL syringe that can measure a 0.5 mL or 0.6 mL dose¹. A U-100 syringe marks 100 units per mL, so 0.5 mL is the 50-unit mark and 0.6 mL is the 60-unit mark.

Dose	Single-dose vial	Draw	Multi-dose vial (4 doses)	Draw
2.5 mg	2.5 mg/0.5 mL	0.5 mL (50 units)	10 mg/2.4 mL (4.17 mg/mL)	0.6 mL (60 units)
5 mg	5 mg/0.5 mL	0.5 mL (50 units)	20 mg/2.4 mL (8.33 mg/mL)	0.6 mL (60 units)
7.5 mg	7.5 mg/0.5 mL	0.5 mL (50 units)	30 mg/2.4 mL (12.5 mg/mL)	0.6 mL (60 units)
10 mg	10 mg/0.5 mL	0.5 mL (50 units)	40 mg/2.4 mL (16.7 mg/mL)	0.6 mL (60 units)
12.5 mg	12.5 mg/0.5 mL	0.5 mL (50 units)	50 mg/2.4 mL (20.8 mg/mL)	0.6 mL (60 units)
15 mg	15 mg/0.5 mL	0.5 mL (50 units)	60 mg/2.4 mL (25 mg/mL)	0.6 mL (60 units)

The pattern is the point: with brand vials the volume never changes. The vial strength changes with your dose, so a new dose means a new vial, not a different number of units.

How many units is my compounded tirzepatide dose?

Compounded vials are different. The compounding pharmacy sets the concentration (mg per mL), it isn't standardized, and it can differ between pharmacies and even between batches. So the same dose can be a very different number of units:

Units to draw = (your mg dose ÷ your vial's mg/mL) × 100

Here is that formula worked out at three example concentrations. Use the column that matches the concentration printed on your own vial, and if your vial isn't one of these, do the math with your own number.

Dose	Vial at 5 mg/mL	Vial at 10 mg/mL	Vial at 20 mg/mL
2.5 mg	50 units (0.5 mL)	25 units (0.25 mL)	12.5 units (0.125 mL)
5 mg	100 units (1 mL)	50 units (0.5 mL)	25 units (0.25 mL)
7.5 mg	150 units (1.5 mL)	75 units (0.75 mL)	37.5 units (0.375 mL)
10 mg	200 units (2 mL)	100 units (1 mL)	50 units (0.5 mL)
12.5 mg	250 units (2.5 mL)	125 units (1.25 mL)	62.5 units (0.625 mL)
15 mg	300 units (3 mL)	150 units (1.5 mL)	75 units (0.75 mL)

Anything over 100 units is more than a standard 1 mL syringe holds. If your math lands there, or lands on a half-unit mark you can't read, that's a reason to call the pharmacy, not to split the dose on your own.

Worked examples

Say a compounded tirzepatide vial is labeled 10 mg/mL and your dose is 2.5 mg, the labeled starting dose¹. Divide 2.5 by 10 to get 0.25 mL, then multiply by 100 to get 25 units. If your pharmacy's vial is labeled 5 mg/mL instead, the same 2.5 mg dose is 2.5 ÷ 5 = 0.5 mL, or 50 units. Same drug, same dose, twice the units, purely because the concentration is different. That's the whole risk in one example.

The math is identical for semaglutide. A 1 mg dose from a vial labeled 2 mg/mL is 1 ÷ 2 = 0.5 mL, or 50 units; from a 5 mg/mL vial it's 0.2 mL, or 20 units. Wegovy's labeled weekly doses are 0.25, 0.5, 1, 1.7 and 2.4 mg, and the label now allows some adults to go up to 7.2 mg after at least 4 weeks on 2.4 mg². For the full semaglutide schedule in units at common vial strengths, see the semaglutide dosage chart.

Why is getting the units wrong a safety issue?

Drawing the wrong number of units because you assumed a concentration is the same mistake as a pharmacy dispensing error, except it happens at home with nobody double-checking. Doubling a dose by using the wrong concentration can sharply increase stomach side effects and push you above anything tested in the trials. Under-dosing the same way means paying for medicine you aren't getting the effect of. Before every new vial, not just the first, read the mg/mL on that vial's label, redo the math even if your dose hasn't changed, and write the unit number down where you'll see it when you inject. If the result is far from what you drew from your last vial, call the pharmacy before injecting.

For the injection itself once you've drawn the right volume, see how to inject Ozempic or Wegovy; if your vial arrived as a powder, how to reconstitute compounded tirzepatide covers how the water you add sets the concentration. If you're still deciding on a compounded prescription, is compounded tirzepatide still legal, is compounded semaglutide legit and safe and the real monthly cost of compounded GLP-1s cover the questions that usually come first. Not medical advice: confirm your vial's concentration and your dose with your prescriber or pharmacist, and see our medical disclaimer.

Frequently asked questions

What is the tirzepatide dosage chart?

Per the Zepbound label: 2.5 mg once weekly for 4 weeks, then 5 mg, then increases of 2.5 mg after at least 4 weeks on each dose, through 7.5, 10 and 12.5 mg to a 15 mg weekly maximum. The maintenance doses for weight reduction are 5, 10 or 15 mg; for sleep apnea, 10 or 15 mg.

How many units is a Zepbound vial dose?

Every brand single-dose Zepbound vial holds its dose in 0.5 mL, which is the 50-unit mark on a U-100 syringe. Doses from the four-dose multi-dose vial are 0.6 mL, or 60 units. The vial strength changes with your dose; the volume does not.

How many units is 2.5 mg of tirzepatide?

It depends entirely on your specific vial's concentration (mg/mL), which is set by the compounding pharmacy and is not standardized. At 10 mg/mL, 2.5 mg is 25 units; at 5 mg/mL, the same 2.5 mg dose is 50 units. Always use the concentration printed on your own vial, not a chart from another prescription.

How do I convert a compounded GLP-1 mg dose to syringe units?

Divide your prescribed mg dose by your vial's labeled concentration in mg/mL to get the volume in mL, then multiply by 100 (since a U-100 insulin syringe reads 100 units per mL). Units = (mg dose ÷ mg/mL concentration) × 100.

Why isn't there one standard units chart for tirzepatide or semaglutide?

Because compounded vial concentrations vary by pharmacy and even by batch — unlike brand-name pens, which use a fixed concentration. A units chart is only valid for the exact concentration it was built for; using it with a different vial can significantly over- or under-dose you.

References

U.S. Food and Drug Administration (2026). ZEPBOUND (tirzepatide) Prescribing Information — Dosage and Administration; Dosage Forms and Strengths (SPL effective August 28, 2026). DailyMed, U.S. National Library of Medicine. https://www.dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=487cd7e7-434c-4925-99fa-aa80b1cc776b
U.S. Food and Drug Administration (2026). WEGOVY (semaglutide) Prescribing Information — Dosage and Administration (SPL effective June 18, 2026). DailyMed, U.S. National Library of Medicine. https://www.dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ee06186f-2aa3-4990-a760-757579d8f77b

Medical disclaimer: This content is for general educational purposes only and is not medical advice, diagnosis, or treatment. Always consult a licensed healthcare professional before starting, stopping, or changing any treatment.