GLP-1 Units to mg Converter
Medically reviewed by Dr. Chhaya Makhija, MD, DipABLM — October 2026
Convert a dose your prescriber has already set between milligrams and units on a U-100 syringe, using the concentration printed on your own vial.
Why a “unit” means something different here
A unit marking on an insulin syringe measures volume, not drug. The marks are calibrated so that 100 units fill exactly 1 millilitre. For U-100 insulin one unit always carries the same amount of insulin, because that concentration is standardised across manufacturers.
GLP-1 medicines have no equivalent standard. A vial may be 1 mg/mL, 2.5 mg/mL, 5 mg/mL or something else entirely, and the figure differs between suppliers and between refills from the same supplier. The same 20 units therefore carries a different amount of drug depending on which vial it came from.
The underlying arithmetic is identical to the one our units to mL calculator performs for insulin, and the same U-100 markings are being read. Only the assumption of a fixed concentration disappears. If you are unsure which markings your syringe carries, the insulin syringe calculator explains the sizes and what each line represents.
That is the whole reason this conversion causes trouble. A unit number that was correct last month is not automatically correct for a new vial. The arithmetic is simple; the error happens when the concentration is assumed instead of read.
Units on a U-100 syringe by dose and concentration
Every figure below is the same calculation: milligrams divided by milligrams per millilitre, multiplied by 100. The concentrations shown are examples to illustrate the arithmetic, not a list of products.
| Dose | 1 mg/mL | 2 mg/mL | 2.5 mg/mL | 5 mg/mL | 10 mg/mL |
|---|---|---|---|---|---|
| 0.25 mg | 25 u | 12.5 u | 10 u | 5 u | 2.5 u |
| 0.5 mg | 50 u | 25 u | 20 u | 10 u | 5 u |
| 1 mg | 100 u | 50 u | 40 u | 20 u | 10 u |
| 2.5 mg | 250 u | 125 u | 100 u | 50 u | 25 u |
| 5 mg | 500 u | 250 u | 200 u | 100 u | 50 u |
Read across a row and the point becomes obvious: one dose maps to five different unit numbers. Read down a column and a fixed unit number maps to five different doses. Neither the dose nor the unit count means anything without the concentration beside it.
Pens are dialled, not drawn
If your medicine came as a pen device, this converter does not apply to it. A pen is dialled to a dose and delivers that dose directly, so there is no syringe marking to translate. Applying syringe arithmetic to a pen is a route to the wrong amount.
The conversion question arises almost entirely with vials, where a dose has to be drawn up by hand. If you are unsure which you have, the pharmacy that dispensed it can tell you in a sentence.
Everything on this page is arithmetic rather than advice. For the insulin tools this conversion is built on, see our unit conversion calculators.
Limitations & Safety Notes
This page performs one calculation and makes no clinical recommendation. It does not set doses, suggest increases, or indicate whether a dose is appropriate for anyone.
The concentration must come from the label on the vial in your hand. Concentrations are not standardised for these medicines and vary between suppliers and between batches. An assumed concentration produces a confidently wrong answer.
The FDA has received reports of adverse events, some requiring hospitalisation, that may be related to dosing errors with compounded semaglutide, including confusion between millilitres, milligrams and units. If the arithmetic here disagrees with what you were told to inject, do not inject. Contact the prescriber or pharmacy and resolve the difference first.
Sources
- U.S. Food and Drug Administration. FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products (July 2024). Link
- Syringe conversion follows the U-100 standard used throughout this site: 100 units per millilitre. See our units to mL calculator for the same arithmetic applied to insulin concentrations.
Written by Ryan Mitchell · Last updated: October 2026
Frequently Asked Questions: GLP-1 Units and mg
How many mg is 50 units of semaglutide?
It depends entirely on the concentration of your vial, so the question has no single answer. On a U-100 syringe, 50 units is 0.5 mL. If the vial is 1 mg/mL that 0.5 mL holds 0.5 mg; if it is 2.5 mg/mL the same 50 units holds 1.25 mg; if it is 5 mg/mL it holds 2.5 mg. Read the concentration from your own label and the converter above does the arithmetic.
How do I convert mg to units?
Divide the dose in mg by the concentration in mg/mL to get millilitres, then multiply by 100, because a U-100 syringe marks 100 units per millilitre. A 1 mg dose from a 2.5 mg/mL vial is 1 divided by 2.5, which is 0.4 mL, which is 40 units.
Why do syringe units not mean the same thing for GLP-1 as for insulin?
A unit on an insulin syringe is a volume marking, not a fixed amount of drug. For U-100 insulin one unit always means the same quantity because the concentration is standardised. GLP-1 medicines have no such standard, so the same unit marking carries a different amount of drug from one vial to another.
Does this work for Ozempic, Wegovy, Mounjaro or Zepbound pens?
No. Those are pen devices where the dose is dialled on the pen, not drawn into a syringe. This converter applies to a vial measured with a syringe. Using syringe arithmetic on a pen dose is a common source of error.
Is 10 units the same dose every time?
Only if the concentration never changes. If a refill arrives at a different concentration, the same 10 units delivers a different amount of drug. Check the concentration on every new vial rather than reusing a unit number that worked before.