GLP-1 Units to mg Dosage Chart: Semaglutide & Tirzepatide

Compounded semaglutide and tirzepatide are prescribed in milligrams but drawn into the syringe in units — and getting that conversion wrong is one of the most common compounded GLP-1 dosing errors. The reason is that the vial is liquid, the syringe is a U-100 insulin syringe, and the relationship between "units on the syringe" and "milligrams of drug delivered" depends entirely on the concentration printed on the vial label. This article is the complete static reference: the formula, the lookup tables for every common compounded concentration of semaglutide and tirzepatide, and the worked math behind the most-searched dosing questions on Google. If you want an interactive version, the same math powers our GLP-1 unit converter.

The formula (the only one you need)

Every standard insulin syringe sold in the US is labeled U-100, which means 100 units = 1 mL. One unit is therefore exactly 0.01 mL of liquid. This is the global insulin-syringe standard set by the FDA and used by BD, Easy Touch, ReliOn, and every other major brand^[5][6].

A compounded GLP-1 vial is a known concentration of active drug dissolved in sterile water — for example, 5 mg/mL tirzepatide or 10 mg/mL semaglutide. The concentration is printed on the vial label by the compounding pharmacy. To translate between "mg of drug" and "units on the syringe," use:

That is the entire math. Everything else in this article is the result of applying those two equations to every common dose at every common concentration.

Common compounded concentrations (2026)

Compounding pharmacies do not all use the same concentration. The most common ones we have observed across US 503A compounding pharmacies as of 2026 are:

• Semaglutide: 2 mg/mL, 5 mg/mL, 10 mg/mL, and 25 mg/mL. The 2 mg/mL and 5 mg/mL strengths are by far the most common; the 10 mg/mL and 25 mg/mL strengths show up in higher-titration kits and stack vials.
• Tirzepatide: 5 mg/mL, 10 mg/mL, 20 mg/mL, 30 mg/mL, and 40 mg/mL. The 5 mg/mL and 10 mg/mL strengths are the most common starting kits; 20-40 mg/mL appear in maintenance and high-dose vials so the patient can draw fewer units per injection.

These are the columns in the reference tables below. If your vial is a concentration that is not listed, plug the number into the formula above (or use the interactive calculator) to get an exact answer.

Semaglutide: complete units-by-dose reference table

For each FDA-style titration dose of semaglutide (0.25 mg starter through 2.4 mg Wegovy maintenance dose^[1]), here are the unit measurements at every common compounded concentration. Read across the row for your dose, find your vial concentration column, and that is the unit mark to draw to on the U-100 insulin syringe.

A few of these values do not land on a clean syringe gradation — for example, 1.7 mg at 25 mg/mL works out to 6.8 units, which a U-100 syringe with 1-unit gradations cannot draw precisely. In practice, your pharmacy should ship you a concentration that produces clean unit values for your prescribed dose. If your math gives you a fractional unit smaller than your syringe gradation, call the pharmacy before injecting.

Tirzepatide: complete units-by-dose reference table

Same format for tirzepatide, covering the standard FDA-titration doses from 2.5 mg starter through 15 mg Zepbound maintenance^[3][4].

Notice how dramatically the unit value drops as concentration rises. A 5 mg dose draws 100 units on a 5 mg/mL vial but only 12.5 units on a 40 mg/mL vial. Same drug, same milligrams, eight-fold difference in syringe volume. This is exactly why you cannot share unit instructions between patients on different concentrations.

Worked example: How many units is 2.5 mg of tirzepatide?

This is the most-searched compounded GLP-1 dosing question on Google. The answer depends entirely on your vial concentration. Plugging 2.5 mg into the formula units = (mg × 100) / concentration:

• 5 mg/mL tirzepatide: (2.5 × 100) / 5 = 50 units
• 10 mg/mL tirzepatide: (2.5 × 100) / 10 = 25 units
• 20 mg/mL tirzepatide: (2.5 × 100) / 20 = 12.5 units
• 30 mg/mL tirzepatide: (2.5 × 100) / 30 ≈ 8.3 units (round to nearest 0.5)
• 40 mg/mL tirzepatide: (2.5 × 100) / 40 ≈ 6.25 units

The 5 mg/mL and 10 mg/mL answers (50 and 25 units) are the ones most patients land on, because those are the two most common starter-kit concentrations.

Worked example: How many mg is 40 units of semaglutide?

Inverse formula: mg = (units × concentration) / 100. Plugging in 40 units of semaglutide:

• 2 mg/mL semaglutide: (40 × 2) / 100 = 0.8 mg
• 5 mg/mL semaglutide: (40 × 5) / 100 = 2.0 mg
• 10 mg/mL semaglutide: (40 × 10) / 100 = 4.0 mg
• 25 mg/mL semaglutide: (40 × 25) / 100 = 10.0 mg

This is the safety lesson in one example: 40 units delivers 0.8 mg on the lowest common concentration but 12.5x more drug on the highest. The Wegovy maintenance dose is 2.4 mg^[1], so a patient who accidentally drew 40 units from a 25 mg/mL vial would receive roughly four times the maximum FDA-labeled weekly dose. This is why concentration is the load-bearing field on a compounded vial label.

Worked example: How many mg is 50 units of semaglutide?

• 2 mg/mL semaglutide: (50 × 2) / 100 = 1.0 mg
• 5 mg/mL semaglutide: (50 × 5) / 100 = 2.5 mg
• 10 mg/mL semaglutide: (50 × 10) / 100 = 5.0 mg
• 25 mg/mL semaglutide: (50 × 25) / 100 = 12.5 mg

Note that 5.0 mg and 12.5 mg of semaglutide both exceed the 2.4 mg Wegovy maximum FDA-labeled dose^[1] and the 2.0 mg Ozempic maximum dose^[2]. If you are drawing 50 units and your vial is 10 mg/mL or 25 mg/mL, stop and verify with your prescriber before injecting.

Worked example: How many mg is 20 units of tirzepatide?

• 5 mg/mL tirzepatide: (20 × 5) / 100 = 1.0 mg
• 10 mg/mL tirzepatide: (20 × 10) / 100 = 2.0 mg
• 20 mg/mL tirzepatide: (20 × 20) / 100 = 4.0 mg
• 30 mg/mL tirzepatide: (20 × 30) / 100 = 6.0 mg
• 40 mg/mL tirzepatide: (20 × 40) / 100 = 8.0 mg

20 units is a common "round number" instruction from telehealth clinicians, and the resulting milligram dose spans 1.0 mg (a sub-starter dose) to 8.0 mg (between the 7.5 mg and 10 mg titration steps of Zepbound^[3]). Same syringe mark, eight different milligram outcomes.

Why concentration matters (the only safety point)

The single most important takeaway from this entire reference page is: the same number of units delivers a different milligram dose at every concentration. A unit is a volume measurement on the syringe, not a dose of drug. The drug content of that volume is set by the vial concentration, which is set by the compounding pharmacy.

Telehealth platforms often instruct patients in units rather than milligrams ("draw to the 25 mark") because units are what the patient actually has to do. That works only as long as the concentration in the vial does not change. The most common dosing-error scenarios we see are:

• The pharmacy switched concentrations between refills and the patient kept drawing the old unit count.
• A patient on tirzepatide assumed semaglutide unit instructions translate (they do not — the concentrations are different).
• A patient stacked vials from two pharmacies with different concentrations and used the unit count from the wrong vial.
• A friend or partner started on the same drug at a different concentration and the patient used their unit count.

Every one of those errors is preventable by re-reading the vial label and re-running the unit conversion every time you open a new vial.

How to find your concentration

The concentration should be printed on the vial label by the compounding pharmacy. Look for a value formatted like 5 mg/mL, 10 mg/mL, or 2.5 mg/mL. It is usually printed near the drug name and the lot number. If the label only lists the total mg in the vial and the total mL, divide the two:

For example, a vial labeled "25 mg total / 5 mL" is a 5 mg/mL vial. A vial labeled "10 mg total / 2 mL" is a 5 mg/mL vial. A vial labeled "20 mg total / 2 mL" is a 10 mg/mL vial.

If the concentration is not on the label and you cannot derive it from total mg and total mL, call the pharmacy before injecting. Do not guess. Do not assume it is the same as your last vial. Do not assume it is the same as a friend's vial. The compounding pharmacy keeps the concentration on file for every batch they ship.

Use the interactive calculator instead

Static tables answer the most common cases, but if your dose or concentration is off the chart, our interactive tool runs the same formula in real time and shows you the exact unit mark to draw to (rounded to the nearest 0.5 unit, since that is what an insulin syringe can actually deliver):

• GLP-1 Unit Converter — interactive mg ↔ units calculator with rounding to the nearest syringe gradation. Same engine as the tables on this page; built for the cases the tables do not cover.

Frequently asked questions

What does "units" mean on a syringe?

On a U-100 insulin syringe, 100 units equals exactly 1 mL of liquid^[5]. Each unit is therefore 0.01 mL. The unit is a volume marking, not a dose of drug. The actual milligrams of GLP-1 you draw depends on the concentration of your vial.

Are insulin syringe units the same across brands?

Yes, as long as the syringe is labeled U-100— the global standard for insulin syringes from BD, Easy Touch, ReliOn, and every other major brand. 100 units always equals 1 mL on a U-100 syringe^[6]. U-40 and U-500 syringes exist for veterinary insulin and concentrated human insulin and are not used for compounded GLP-1s. If your compounded GLP-1 kit shipped with a syringe, it is U-100.

Can I use a tuberculin syringe instead?

A tuberculin syringe is graduated in mL rather than units. 0.1 mL on a tuberculin syringe equals 10 units on a U-100 insulin syringe (since 1 unit = 0.01 mL). Tuberculin syringes use a longer, larger-gauge needle that is more painful for subcutaneous injection, so insulin syringes are preferred for compounded GLP-1 administration. The math is identical — you just convert your prescribed unit count to mL by dividing by 100.

How precise are unit measurements?

Standard U-100 insulin syringes are graduated in 1-unit or 0.5-unit increments depending on the syringe size. The smallest 0.3 mL syringes typically have 0.5-unit gradations; the standard 1 mL syringes typically have 1-unit gradations. You cannot reliably draw a fractional unit smaller than the gradation, which is why pharmacies generally ship a concentration that produces clean unit values for the prescribed dose.

What if my pharmacy gives me a different concentration than expected?

Different compounding pharmacies use different concentrations, and the same pharmacy can change concentrations between refills. Always re-read the vial label on every new vial and recalculate your unit dose using the formula above (or the interactive unit converter). Drawing the same number of units from a vial at a different concentration will deliver a different milligram dose. If the concentration changed unexpectedly, call your prescriber and the pharmacy before injecting.

Related research and tools

• GLP-1 Unit Converter (interactive) — the live calculator that runs the same formula as this page, with rounding to the nearest syringe gradation
• Compounded GLP-1 reconstitution and mixing guide — how concentration is set in the first place when you reconstitute a freeze-dried vial with bacteriostatic water
• How to inject a GLP-1: step-by-step technique — once you have the unit count, this is the injection procedure
• Wegovy pen vs compounded vial: practical differences — why brand-name pens dose in mg automatically and compounded vials force you to do this math

Important disclaimer. This article is educational and does not constitute medical advice. The conversion math is verified against FDA-approved labels for Wegovy, Ozempic, Zepbound, and Mounjaro and against the BD U-100 insulin syringe specification, but the clinical decision of what dose to inject is the prescriber's and the patient's responsibility. Always verify your vial concentration on the label, recalculate the unit count for every new vial, and consult your prescribing clinician before changing your dose. If your pharmacy ships a vial at a concentration you did not expect, call them before injecting.