Compounded to Brand Dose Conversion: Turning Your "Units" Into a Wegovy or Zepbound Dose

When patients move off compounded semaglutide or tirzepatide, almost every guide tells them the same thing: bring your dosing records and let your prescriber decide where to land. That is correct — but it skips the part that actually trips people up. Most compounded prescriptions were written in “units,” and a unit count, by itself, does not tell anyone what dose you were on.

This page is the missing math. It explains why “I was taking 25 units” is an incomplete sentence, the one calculation that completes it, and how to turn the result into something a Wegovy or Zepbound prescriber can use. For the broader move — new prescription, access paths, cost, and timing — see our full guide on switching from compounded to brand. If your refill was just cancelled and you are weighing all your options, start at what to do when your compounded GLP-1 is discontinued.

We are an independent publication, not a prescriber or pharmacy. Nothing here is medical advice or a dosing instruction. The calculation below is arithmetic to help you describe your own history accurately; the dose you actually receive is a clinical decision for a licensed professional.

Why “25 units” doesn’t tell anyone your dose

Compounded GLP-1s were typically supplied as a liquid in a multidose vial, and patients drew their weekly dose with an insulin syringe. Those syringes are marked in units, not milligrams. On a standard U-100 insulin syringe, 100 units equals 1 mL of liquid, so one unit is simply 0.01 mL of whatever is in the vial.

That is the trap: a unit measures volume, not drug. How much semaglutide or tirzepatide sits in that 0.01 mL depends entirely on the vial’s concentration, and compounders used a wide range of concentrations. The FDA has explicitly warned that this is a source of real-world dosing errors, noting that instructions for compounded semaglutide may tell patients to inject in “units” — “the volume of which may vary depending on the concentration” — rather than in milligrams or milliliters (FDA dosing-errors alert).

So when a new prescriber asks what dose you were on and you answer “25 units,” you have told them the volume you injected but not the dose you received. The two are only connected through one number: the concentration.

The one calculation that matters

To convert your compounded dose into a milligram figure, you need exactly one piece of information your unit count is missing — the concentration, written in milligrams per milliliter (mg/mL). With it, the conversion is a single line of arithmetic:

Weekly dose (mg) = concentration (mg/mL) × units × 0.01

The × 0.01 step converts units to millilitres (because 1 unit = 0.01 mL on a U-100 syringe). If you prefer to think in two steps: first divide your units by 100 to get millilitres, then multiply by the concentration.

Where to find your concentration:

• The vial label or box — usually printed as a strength such as “5 mg/mL,” or as a total like “10 mg/2 mL” (which is the same as 5 mg/mL).
• Your prescription or the patient instructions that came with the shipment.
• The compounding pharmacy or telehealth provider — they know the concentration they dispensed and can tell you over the phone.

If you genuinely cannot find the concentration, your unit count cannot be converted, and that is worth saying plainly to your new prescriber rather than guessing.

Why the same units can be three different doses

Here is what makes the concentration so important. Take an identical injection — 25 units, or 0.25 mL — and run it through three concentrations a compounder might have used for semaglutide:

Same syringe, same number on the plunger — and a dose that ranges from a low-titration step all the way to the maximum maintenance dose. This is precisely why a unit count handed over without a concentration can lead a prescriber to place you far from where you actually were.

For reference, here is the milligram value of common semaglutide concentrations across a range of unit volumes:

The same logic applies to tirzepatide, which compounders supplied at higher concentrations. A patient injecting 30 units (0.30 mL) of a 20 mg/mL tirzepatide vial was taking 6 mg weekly — between Zepbound’s 5 mg and 7.5 mg steps. Because tirzepatide concentrations varied even more widely than semaglutide, the formula matters more, not less: do not assume your concentration matches anyone else’s.

Mapping your milligram dose onto the branded ladder

Once you have a real milligram figure, you can see where it sits on the fixed branded ladders. The branded products do not offer custom doses — they step in set increments:

• Wegovy (semaglutide): 0.25 mg → 0.5 mg → 1 mg → 1.7 mg → 2.4 mg, with a higher-intensity 7.2 mg option. See our Wegovy dose escalation guide for what each step involves.
• Zepbound (tirzepatide): 2.5 mg → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mg. Our Zepbound dose escalation guide covers the standard titration.

Two honest caveats about this mapping:

Your dose will usually fall between two rungs. Compounded titration was continuous; branded titration is stepped. A calculated 1.25 mg weekly semaglutide lands between the 1 mg and 1.7 mg Wegovy steps, and there is no automatic rule for which way it rounds. That is a clinical judgment based on how you tolerated your dose and whether you have had a gap — not a lookup.

There is no official conversion chart. Because compounded products were never standardized, no regulator or manufacturer publishes an authoritative compounded-to-branded equivalence. Your calculated milligram figure is an accurate description of what you were taking; turning it into a branded starting dose is the prescriber’s call. We explain how that decision tends to go in the dose alignment section of our switching guide.

The salt-form asterisk

There is one more reason to treat your calculated number as a strong estimate rather than an exact equivalence. FDA-approved Wegovy and Ozempic contain base semaglutide. Some compounded products used salt forms — semaglutide sodium or semaglutide acetate — which the FDA says have not been shown to have the same chemical and pharmacologic properties as the approved active ingredient (FDA concerns about unapproved GLP-1 drugs).

In practice, that means if your compounded vial was a salt form, even a correctly calculated milligram figure may not translate milligram-for-milligram to branded semaglutide. It does not make the calculation useless — it remains the best available starting point — but it is a reason to describe your product accurately (including the salt form, if the label states one) and let your prescriber weigh it. For more on how the compounded and branded products differ, see compounded vs brand semaglutide and compounded vs brand tirzepatide.

Continue or restart? The gap rule

A correct milligram figure makes the next question answerable: will a prescriber continue near that dose, or restart you low? The biggest single factor, beyond the prescriber’s own caution, is how long you have been off the drug. Semaglutide and tirzepatide both clear over roughly a week per dose, so a short, well-timed switch carries meaningful drug levels into the first branded injection. A gap beyond about two weeks lets levels fall, and the prescribing guidance points toward reinitiating titration to limit gastrointestinal side effects.

The takeaway is practical: the milligram number tells the prescriber where you were, and the gap tells them how safely they can pick up there. Bring both. Our guide on what to do when your compounded GLP-1 is discontinued covers getting dose continuation agreed in writing before you pay, and our GLP-1 maintenance dose explainer covers where most people settle long-term.

What to hand your prescriber

You do not need to solve the dose yourself — you need to give the prescriber a complete picture instead of a unit count. Put four things on one page:

• Your calculated weekly dose in milligrams, with the concentration you used to get it (for example: “25 units of a 5 mg/mL vial = 1.25 mg/week”).
• The product details, including the salt form if the label names one.
• Your titration history — the doses you stepped through and how long you held each, and how you tolerated them.
• The date of your last injection, so the prescriber can judge any treatment gap.

That is the difference between “I was on 25 units” and “I was on 1.25 mg of semaglutide weekly, tolerated well, last dose six days ago.” The first restarts a guessing game; the second lets a prescriber make an informed decision — and is the simplest protection against losing months of titration. Once the dose conversation is settled, our switching from compounded to brand guide covers the brand cash-pay routes, where Wegovy through NovoCare runs $349/month(as of May 2026) a month and Zepbound vials through LillyDirect start at $299/month.

This article is editorial and informational only. The calculation provided is general arithmetic to help you describe your own dosing history; it is not a dosing instruction, a recommendation, or medical advice. Concentrations, salt forms, and individual tolerance vary, and no compounded-to-branded conversion is officially established. Decisions about what dose to take, and how and when to switch products, belong to you and a licensed healthcare professional.