What does U-100 actually mean?

The syringe is graduated at 100 units per mL, so each unit mark equals 0.01 mL. The “units” have nothing to do with the drug — they are a volume scale borrowed from insulin dosing. That is why the same mg dose reads differently at different concentrations.

My vial says “2.5 mg/0.5 mL” — what do I enter?

Divide first: 2.5 mg ÷ 0.5 mL = 5 mg/mL, and enter 5. Per-volume labels are the most common source of unit confusion the FDA has documented in compounded semaglutide overdose reports — when in doubt, read the label to your pharmacist.

Can I use any syringe I have at home?

No. This math only works on U-100 insulin syringes. A U-40 syringe over-delivers 2.5× at the same mark, and an mL-graduated syringe needs the mL figure, not units. Your pharmacy dispenses the right syringe — ask them, not a drawer.

What if my dose needs more than 1 mL?

Stop and call the pharmacy. Weekly GLP-1 doses at typical concentrations draw well under 1 mL; a bigger volume usually means the concentration was misread or the vial was mislabeled. FDA case reports include 5–20× overdoses from exactly this scenario.

Does this work for Ozempic or Wegovy pens?

No — pens meter the dose mechanically; you never draw or count units. This converter is for vial-and-syringe dispensing, which is how most compounded semaglutide and tirzepatide ships. Pen users can ignore units entirely.

Semaglutide & tirzepatide dose converter: mg ↔ units

Convert a dose in milligrams to units on a U-100 syringe for any vial concentration, with the full table for semaglutide and tirzepatide.

How many units is my dose? · Data: U-100 syringe math · FDA labels · Checked August 27, 2026

This tool explains labeled dosing math. It never replaces your prescription — confirm your vial’s concentration and your syringe type with your pharmacy before drawing anything.

Your prescription

Runs in your browser — nothing is stored or sent.

Molecule

Vial concentration (on the label)

or enter:mg/mL

Prescribed dose (mg per injection)

or enter:mg

A “2.5 mg per 0.5 mL” label is a 5 mg/mL concentration — divide the mg by the mL before entering it.

Semaglutide 0.25 mg · 5 mg/mL vial

U-100 insulin syringe

5 units

0.05 mL draw volume

0 u255075100 u

Draw to the 5-unit mark. Marks on a U-100 syringe are 1 unit = 0.01 mL.

Reverse check — units to mg:units at 5 mg/mL = 0.25 mg

Cite this result: “0.25 mg of semaglutide from a 5 mg/mL vial is 5 units (0.05 mL) on a U-100 syringe” — GLP1.health dose converter, glp1.health/tools/dose-converter, data as of August 27, 2026.

Semaglutide conversion table — units on a U-100 syringe

Dose	1 mg/mL	2.5 mg/mL	5 mg/mL
0.25 mg	25 u · 0.25 mL	10 u · 0.10 mL	5 u · 0.05 mL
0.5 mg	50 u · 0.50 mL	20 u · 0.20 mL	10 u · 0.10 mL
1 mg	100 u · 1.00 mL	40 u · 0.40 mL	20 u · 0.20 mL
1.7 mg	—	68 u · 0.68 mL	34 u · 0.34 mL
2.4 mg	—	96 u · 0.96 mL	48 u · 0.48 mL

Labeled escalation doses per the Wegovy prescribing information. “—” = draw volume over 1 mL; confirm with your pharmacy.

Tirzepatide conversion table — units on a U-100 syringe

Dose	5 mg/mL	10 mg/mL
2.5 mg	50 u · 0.50 mL	25 u · 0.25 mL
5 mg	100 u · 1.00 mL	50 u · 0.50 mL
7.5 mg	—	75 u · 0.75 mL
10 mg	—	100 u · 1.00 mL
12.5 mg	—	—
15 mg	—	—

Labeled escalation doses per the Zepbound prescribing information. “—” = draw volume over 1 mL; confirm with your pharmacy.

How this converter works

A U-100 syringe is graduated for insulin: 100 units per mL, so 1 unit = 0.01 mL. Compounded GLP-1s are usually dispensed in vials and drawn with these syringes, which is why prescriptions written in mg have to be translated: units = (mg ÷ mg/mL) × 100, and draw volume = mg ÷ mg/mL.

The dose lists come from the FDA labels — Semaglutide (0.25 → 2.4 mg) and Tirzepatide (2.5 → 15 mg). The tool refuses to output a result when the computed draw exceeds 1 mL or the dose exceeds the highest labeled dose — both are red flags the FDA’s alert on compounded dosing errors tells patients to resolve with a pharmacist, not a calculator.

Limits: concentrations vary by pharmacy and can change between refills of the same program; some pharmacies dispense U-40 or mL-graduated syringes where this math does not apply. This tool never suggests a dose — it only translates the one on your label.

The three numbers to check before every injection

Concentration on the vial, in mg/mL

If the label reads “mg per 0.5 mL,” convert it first. New refill, new check — it can change.

Syringe type — U-100 or not

This math is U-100 only. A U-40 syringe or an mL-graduated syringe reads completely differently.

The dose on your prescription, in mg

FDA case reports document 5–20× overdoses from confusing units, mg and mL. When any number surprises you, call the pharmacy.

Questions

Unit questions, answered directly

It depends entirely on concentration: 25 units from a 1 mg/mL vial, 10 units from 2.5 mg/mL, 5 units from 5 mg/mL — always on a U-100 syringe. There is no universal answer, which is exactly why the vial label matters more than any chart.

This tool explains labeled dosing math; it never replaces your prescription or your pharmacist. Never adjust a dose without your prescriber. If you may have injected more than prescribed, contact your prescriber or Poison Control (1-800-222-1222) now.

Data sources · cited with retrieval dates

FDA prescribing informationThe labels for every product a tool names, on the label holder’s own site
Manufacturer cash programsNovoCare, LillyDirect and TrumpRx published self-pay prices
CMS NADACNational Average Drug Acquisition Cost, weekly file

NADAC figures are pharmacy acquisition costs, not retail prices and not what you will pay. This content is educational and is not medical advice.

The data behind this tool · 7 pages

GLP-1 medications Dulaglutide online Exenatide online Liraglutide online Orforglipron online Semaglutide online Tirzepatide online