Compounded tirzepatide dosage: prescription mg to syringe units

A compounded tirzepatide dose is written in milligrams on the prescription, the vial label states a concentration in mg/mL, and the syringe reads in units: units = mg ÷ (mg/mL) × 100. Below are the approved 2.5–15 mg steps converted to units at four common vial concentrations, and a converter for any other.

Compounded tirzepatide has no FDA label of its own, so this page publishes no compounded schedule. It takes the three numbers a vial prescription gives you, shows where each one comes from, converts the approved milligram steps into syringe units, and ends with what to write down every week so a vial change never silently moves a syringe mark.

What a compounded prescription actually specifies#

A compounded tirzepatide prescription resolves to three numbers, and only one of them is arithmetic. The dose in milligrams comes from the prescriber. The concentration in mg/mL comes from the pharmacy label — printed outright on a pre-mixed vial, or implied by the milligrams of powder in a dry vial plus the millilitres the pharmacy tells you to add. The beyond-use date comes from that same label, and it is the only expiry that applies to the vial.

Two of those three numbers are the whole conversion: dose ÷ concentration × 100 is the syringe reading on a U-100 insulin syringe, where 100 units is 1 mL. The third number never enters the formula, but it decides whether the vial in front of you is usable at all, which is why it belongs in the same log entry. Where the syringe itself comes from is a separate question; the guide to pen needles and syringes covers why a vial needs a U-100 syringe rather than a pen needle.

Tirzepatide compound dosage chart in units#

Compounded tirzepatide has no FDA label. The milligram steps on your prescription are set by your prescriber; the approved ladder below is the only published reference for what those steps look like, and the chart converts those steps to units. If your prescription uses different numbers, the converter takes any dose.

The approved ladder is 2.5 mg once weekly for four weeks, then 5 mg, with further increases in 2.5 mg increments after at least four weeks on the current dose, up to a 15 mg maximum — from the Zepbound prescribing information (checked 2026-09-02). Every step, its role, and the four-week floor are laid out in the tirzepatide dosage chart, and the Zepbound dosage chart covers the same rungs with that label’s maintenance dosages.

The four concentrations below are strengths compounded vials commonly carry — 5, 10, 17 and 25 mg/mL — chosen to show the range, not recommended by anyone. A vial at any other mg/mL moves every number in its column, and the converter under the table takes that case.

† More than 100 units — that volume does not fit in one 1 mL U-100 syringe, which stops at 100 units. At 5 mg/mL only the first two steps fit a single syringe; at 10 mg/mL the last two run over; at 17 and 25 mg/mL every step fits. Exactly 100 units is a full 1 mL draw, which is where 5 mg at 5 mg/mL and 10 mg at 10 mg/mL land. The 17 mg/mL column does not land on whole units — 14.7, 29.4, 44.1, 58.8, 73.5 and 88.2 are rounded to one decimal, and how finely a particular syringe can be read depends on the gradations printed on its barrel.

The converter runs the same formula for any dose and any concentration, so a prescription that does not use the approved steps, or a vial at 8 or 12 mg/mL, gets the same answer the table would. The full units calculator also runs it backwards — from a syringe mark to milligrams — for checking a draw that has already been made.

Dry vial: concentration comes from the water#

A dry vial has no concentration until the diluent goes in, because the number printed on it is milligrams of powder, not mg/mL. The water volume decides the strength: 10 mg of tirzepatide with 1 mL of bacteriostatic water makes 10 mg/mL, and the same 10 mg with 2 mL makes 5 mg/mL. The dose does not change between those two — 2.5 mg is still 2.5 mg — but the syringe mark doubles from 25 units to 50. That volume is the pharmacy’s instruction, printed with the vial or given when it was dispensed, and this page does not choose it. The reconstitution calculator does the two-step arithmetic — water volume to concentration, then concentration to units — and can also work backwards from a round number of units to the water volume that produces it. Whatever concentration you end up with is the number to write on the vial and in the log, because from that point the powder figure on the label is no longer the one that matters.

Multi-dose vial: counting what’s left#

A multi-dose vial is one container that several weekly doses come out of, so the running question is how much is left — in milligrams, because that is the unit of the prescription, and in units, because that is what the syringe shows. Both follow from the same two numbers: what the vial held to begin with and what each draw took.

1. 🏷️ Step 1

   Start from the label

   Total mg in the vial, or vial mg ÷ diluent mL if it started dry. A 20 mg vial at 10 mg/mL holds 2 mL, which is 200 units of liquid in total.

2. ➖ Step 2

   Subtract each dose in mg

   Two 5 mg draws take 10 mg out. Remaining: 20 − 10 = 10 mg. Milligrams first, because that is the figure the prescription and the log share.

3. 💉 Step 3

   Convert the remainder to units

   10 mg ÷ 10 mg/mL × 100 = 100 units, or 1 mL — enough for two more 5 mg doses at 50 units each, if every draw was exact.

4. 📅 Step 4

   Check it against the beyond-use date

   Doses that fall after the BUD on the pharmacy label are not doses, however many milligrams the subtraction says remain in the vial.

The arithmetic assumes every draw was exact. In practice a little liquid stays in the needle hub and the syringe dead space on each draw, so the last dose in a vial can come up short of what the subtraction predicts. Whether a short final draw counts as a dose, and what to do with the vial when it does not, are questions for the pharmacist who dispensed it — not for a subtraction. Writing the remaining milligrams into the log after every injection is what makes the shortfall visible before the week it matters.

What to write in the log#

A compounded vial adds numbers to the weekly entry that a pen never needed. The guide to what to track on GLP-1 covers the four entries every injection gets — date, dose, site, one weigh-in — and a vial prescription needs four numbers of its own next to the dose.

Log units and milligrams together, never one alone: 50 units means nothing next month without the concentration that produced it, and a milligram figure by itself is not what you drew. The tirzepatide tracker page shows how those fields sit next to a brand pen entry in the same history, so a switch between containers does not break the record. On the phone, the GLP-1 shot tracker app keeps the four numbers with each injection date, reminds you on shot day, and remembers which vial and which concentration the current run is on.

What this page cannot tell you#

It cannot tell you what dose to be on. The milligrams in every table came from the approved product label, and the milligrams on your prescription came from your prescriber; if the two differ, the prescription wins and the table is only an illustration. Nothing here suggests raising, lowering, holding, or spacing a dose, and it does not say when a step should change — that call depends on response and tolerability and belongs to the prescriber.

It does not translate between products. A compounded vial and a brand pen or vial are prescribed separately, and no label publishes an equivalence between them. Moving from one to the other is a prescribing decision with its own instructions, and this page does not do arithmetic across that line.

It does not set a storage window. Compounded vials carry a beyond-use date assigned by the pharmacy, and the room-temperature windows printed for Mounjaro and Zepbound pens and vials describe a different product in a different container. The GLP-1 fridge timer counts down those brand-label windows, which is useful if a brand pen is also in the fridge, and says nothing about a compounded vial — for that, the pharmacy label is the whole answer.

It says nothing about where a vial came from, how it was prepared, or how to mix and draw from it. Every one of those is a question for the pharmacy that dispensed the vial or the prescriber who wrote for it, and a web page is the wrong place to get any of them answered.

What it does hand you is a concentration and a units figure, and those two numbers are worth writing down every time the vial changes — because a new vial at a new strength silently changes every syringe mark that follows.

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