Guide · Updated November 2026

Tirzepatide Dosage Chart: How Many Units Is Each mg?

Q: What syringe size should I use for compounded tirzepatide?

Whatever size your pharmacy ships with your prescription. Smaller doses are generally easier to measure accurately on a smaller-capacity syringe (0.3 mL or 0.5 mL) because the unit markings are spaced further apart.

"How many units is 5mg of tirzepatide?" has no single answer. It depends entirely on the concentration printed on your vial, which varies by pharmacy. Brand-name Mounjaro and Zepbound come in fixed-dose presentations with their own instructions, so a compounded units chart does not apply to them. This guide covers the FDA-approved dosing schedule, the conversion formula for compounded vials, and example math across a range of concentrations. Checked against the current Mounjaro and Zepbound labels and FDA pages on November 4, 2026.

Why “Units” Comes Up at All

Mounjaro and Zepbound now come in four presentations, according to the current labels: pre-filled single-dose pens, single-dose vials holding one 0.5 mL dose, multi-dose vials, and single-patient-use KwikPens. The multi-dose vials and KwikPens hold four doses of 0.6 mL each, and each strength is made so that 0.6 mL equals the labeled dose (Mounjaro label, Zepbound label). Zepbound is sold through LillyDirect. If you use a brand vial, draw the volume in Lilly’s instructions for use with the syringe they specify, not a number from this page.

The “units” question comes almost entirely from compounded tirzepatide, which is often dispensed as a multi-dose vial that you draw from yourself using a small insulin syringe. Compounded tirzepatide is not FDA-approved and is not a generic version of Mounjaro or Zepbound. The FDA declared the tirzepatide shortage resolved, and its temporary flexibility for compounders ended in March 2025 (FDA). It is a copy of the active ingredient mixed by a compounding pharmacy, and because pharmacies mix it at different strengths, the same prescribed dose can look like a completely different number of units depending on which vial is in your fridge.

This page is a reference for understanding that math, not a substitute for the dosing instructions your prescriber and pharmacy gave you. If the number you calculate does not match what is printed on your pharmacy label, trust the label and call the pharmacy before you draw anything up. The FDA has received reports of people taking 5 to 20 times the intended dose of compounded semaglutide after mix-ups between units, milliliters and milligrams (FDA alert). The same kind of error can happen with any compounded vial.

I have been on brand Mounjaro since 2024, so I have never had to draw a dose myself. But readers ask me this question constantly, usually after switching pharmacies or comparing notes with someone else on the same mg dose who reports a completely different unit count. The mismatch is almost always the concentration, not an error.

The FDA-Approved Dose Levels

The Mounjaro and Zepbound labels set a six-step dose ladder: start at 2.5 mg weekly for 4 weeks, then go to 5 mg, and increase in 2.5 mg steps only after at least 4 weeks on the current dose, if needed (Mounjaro label). Your prescriber decides whether and when you step up. Compounded products have no FDA-approved dosing, so follow your prescriber.

Dose	Typical Minimum Duration	Status
2.5 mg	4 weeks	Starting dose, for treatment initiation only
5 mg	4 weeks	First therapeutic dose
7.5 mg	4 weeks	Titration step or maintenance
10 mg	4 weeks	Titration step or maintenance
12.5 mg	4 weeks	Titration step or maintenance
15 mg	Ongoing	Maximum FDA-approved dose

Our Mounjaro dosage titration guide covers what each of these steps feels like in practice, dose by dose. This page is only about converting the mg number on your prescription into a units number on a syringe, for the vials where that step is necessary.

Both labels carry a boxed warning about thyroid C-cell tumors, and tirzepatide is contraindicated if you or a family member has had medullary thyroid carcinoma or if you have MEN 2. The labels also warn about pancreatitis, gallbladder disease and kidney injury from dehydration, and Zepbound should be stopped if pregnancy is recognized (Zepbound label).

The Conversion Formula

Compounded tirzepatide vials are drawn up with a standard U-100 insulin syringe, where the barrel is marked in units and 100 units always equals 1 mL, regardless of what is dissolved in that milliliter. The concentration on your vial label (in mg per mL) is what turns a units mark into a specific dose.

Units = (Prescribed dose in mg ÷ Vial concentration in mg/mL) × 100

Two examples make the point:

A 5 mg dose drawn from a 10 mg/mL vial: (5 ÷ 10) × 100 = 50 units
The same 5 mg dose drawn from a 20 mg/mL vial: (5 ÷ 20) × 100 = 25 units

Same prescription, same 5 mg, half the number on the syringe. Neither number is wrong. They are two different concentrations delivering the same dose. This is exactly why a units chart copied from a forum post or a different pharmacy’s website can lead someone to draw the wrong amount.

Before you draw anything: Check the concentration (mg/mL) printed on your specific vial label. Compounding pharmacies do not use a single industry-standard concentration. If your pharmacy's instructions and the chart below disagree, the pharmacy's label is correct, not this page.

Units by Common Concentration

Concentrations vary by pharmacy, and some pharmacies pick a concentration so doses land on clean, easy-to-read numbers. The table below shows the formula applied to a range of example concentrations. It is not a list of what any pharmacy uses. Use it to sanity-check your own label, not to replace it.

Prescribed Dose	5 mg/mL	10 mg/mL	12.5 mg/mL	20 mg/mL	30 mg/mL
2.5 mg	50 units	25 units	20 units	12.5 units	8.3 units
5 mg	100 units	50 units	40 units	25 units	16.7 units
7.5 mg	150 units*	75 units	60 units	37.5 units	25 units
10 mg	200 units*	100 units	80 units	50 units	33.3 units
12.5 mg	250 units*	125 units*	100 units	62.5 units	41.7 units
15 mg	300 units*	150 units*	120 units*	75 units	50 units

*Exceeds the 100-unit capacity of a standard 1 mL (100-unit) insulin syringe. A dose marked with an asterisk means either the concentration is too dilute for that dose to fit in one syringe, or your pharmacy uses a larger syringe or a different draw method. This is a sign to call your pharmacy, not a math error to work around yourself.

Notice that fractional units (8.3, 16.7, 33.3, 41.7) show up at the 30 mg/mL concentration. Standard insulin syringes are marked in whole-unit or half-unit increments, not tenths. If your calculation lands on a fraction, your pharmacy has either rounded it in your instructions or chosen a different concentration for your specific dose. A fraction you cannot see marked on your syringe is a reason to call the pharmacy, not a reason to estimate.

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Syringe Sizes and Why They Matter

Insulin syringes come in three common sizes, and picking the wrong one makes small doses hard to read accurately:

Syringe Size	Total Units	Best For
0.3 mL (30-unit)	30 units	Small doses, marked in 1-unit increments, easiest to read precisely at low volumes
0.5 mL (50-unit)	50 units	Mid-range doses
1 mL (100-unit)	100 units	Larger doses, coarser gradations that make small doses harder to measure precisely

A 12.5-unit dose drawn on a 100-unit syringe is a short, hard-to-read line near the bottom of the barrel. The same 12.5-unit dose drawn on a 30-unit syringe fills almost half the barrel and is much easier to measure accurately. Ask your pharmacy which syringe size ships with your specific concentration and dose, and use that one rather than whatever insulin syringe you may have on hand from another prescription.

Common Mistakes People Make

Using a chart from a different pharmacy. The most common error is applying a units chart found online to a vial from a pharmacy that mixes at a different concentration. Always match the chart to the exact mg/mL printed on your label.

Using this chart for brand vials or KwikPens. Do not. Brand single-dose vials hold one 0.5 mL dose. Brand multi-dose vials and KwikPens deliver four 0.6 mL doses at a concentration matched to the labeled strength. Use Lilly’s instructions for use, not this chart.

Confusing mL with units. On any U-100 insulin syringe, 100 units equals 1 mL, so 0.5 mL is always 50 units, whether the syringe holds 0.3 mL, 0.5 mL or 1 mL. A smaller barrel only spaces the markings further apart. It does not change what a unit means. If your instructions are written in mL, ask your pharmacy to restate them in units for the syringe they ship.

Rounding aggressively. A fractional unit result is a signal to call the pharmacy, not a cue to round to the nearest whole number on your own. Compounding pharmacies that use uneven concentrations usually provide written, dose-specific draw instructions for exactly this reason.

FAQ

How many units is 5mg of tirzepatide?

It depends entirely on your vial’s concentration. At 10 mg/mL, 5 mg is 50 units. At 20 mg/mL, the same 5 mg is 25 units. There is no single correct answer without knowing the mg/mL printed on your specific vial.

Why don’t Mounjaro or Zepbound require unit conversion?

Brand-name Mounjaro and Zepbound come as single-dose pens, single-dose vials (one 0.5 mL dose), and multi-dose vials or KwikPens (four 0.6 mL doses). Each strength is made so the labeled volume equals the labeled dose, and Lilly’s instructions for use tell you how to give it. Unit conversion from a chart is only relevant for compounded tirzepatide dispensed in multi-dose vials.

Is compounded tirzepatide the same as Mounjaro or Zepbound?

No. Compounded tirzepatide is not FDA-approved and is not a generic version of Mounjaro or Zepbound. It is prepared by a compounding pharmacy and is meant to contain the same active ingredient, but it has not gone through FDA review for safety, effectiveness, or manufacturing quality the way the brand products have. Whether a compounded product is appropriate for a given patient is a decision for a licensed prescriber, not something this chart determines.

What if my calculated dose comes out to a fraction of a unit?

Call your pharmacy before drawing anything. A fractional result usually means the concentration on your vial does not divide evenly into your prescribed dose, and your pharmacy should have already given you rounded, dose-specific instructions. Do not estimate a fractional unit by eye on the syringe.

What syringe size should I use for compounded tirzepatide?

Whatever size your pharmacy ships with your prescription. As a general rule, smaller doses are easier to measure accurately on a smaller-capacity syringe (0.3 mL or 0.5 mL) because the unit markings are spaced further apart. A 1 mL syringe is better suited to larger-volume draws.

This guide is for general information only, not medical advice, and does not tell you what dose to take or how to administer it. Compounded tirzepatide is not FDA-approved and is not a generic version of Mounjaro or Zepbound. Only a licensed prescriber and your dispensing pharmacy can tell you the correct dose and draw volume for your specific prescription. Full details in our disclaimer.

Guides:

Medications: Compounded Tirzepatide · Mounjaro · Zepbound

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What we checked

This AI-assisted public-source desk check reviewed the current Mounjaro and Zepbound prescribing information, the FDA’s alert on dosing errors with compounded GLP-1 vials, and the FDA’s update on tirzepatide compounding policy on November 4, 2026, and rechecked the arithmetic in the chart. This is not a clinical review and it is not medical advice. Prices and policies change, so confirm them with the provider or your prescriber before you act.