Free GLP-1 Safety Tool
GLP-1 Unit Converter
Convert milligrams, millilitres and syringe units accurately using your medication concentration, while understanding what those numbers actually mean.
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The label always wins. Every number on this page depends on the concentration printed on your vial. If a result here disagrees with what your prescriber or pharmacist told you to draw, do not inject. Call them.
How to Convert mg to Units for a GLP-1
Divide your dose in milligrams by your vial's concentration in mg/mL to get the volume in millilitres, then multiply by 100 to get insulin syringe units. A U-100 syringe always holds 100 units in 1 mL. For example, 1 mg from a 5 mg/mL vial is 0.2 mL, which is 20 units.
That is the entire calculation, and it never changes. What changes is the concentration, and that is why the same prescribed dose produces a different number of units for different people. The concentration is the only variable, and it is printed on your label.
| Step | Formula | Example: 1 mg at 5 mg/mL |
|---|---|---|
| 1. Volume | dose (mg) ÷ concentration (mg/mL) | 1 ÷ 5 = 0.2 mL |
| 2. Units | volume (mL) × 100 | 0.2 × 100 = 20 units |
| 3. Check | does it fit and land on a line? | 20 units fits a 30-unit syringe |
Safety tip: run the calculation in the direction you are actually working. If your pharmacist told you a number of units, convert units back to mg and check it matches the dose your prescriber wrote.
Why Concentration Matters More Than Anything Else
Concentration is how much drug is dissolved in each millilitre of liquid, written as mg/mL. It is the number that turns a dose into a volume. Two vials can contain identical medication at different strengths, so the same 1 mg dose might be 40 units from one vial and 20 units from another.
This is the single most common source of anxiety, and of genuine error, with compounded GLP-1 medication. A units figure is meaningless without the concentration it came from. If you switch pharmacies, switch vials, or your pharmacy reformulates, you must redo the conversion rather than reuse a number you remember.
| Concentration | Volume to draw | Units on a U-100 syringe |
|---|---|---|
| 1 mg/mL | 1.00 mL | 100 units |
| 2.5 mg/mL | 0.40 mL | 40 units |
| 5 mg/mL | 0.20 mL | 20 units |
Safety tip: never carry a units number across to a new vial. Read the concentration on the new label first, every single time.
How to Read an Insulin Syringe
Insulin syringes are marked in units, not millilitres, and U-100 syringes hold 100 units per 1 mL. They come in 30-unit (0.3 mL), 50-unit (0.5 mL) and 100-unit (1 mL) barrels. Smaller barrels spread fewer units over the same length, which makes small GLP-1 doses far easier to measure accurately.
The practical consequence is that the best syringe is the smallest one your dose fits inside. A 20-unit dose on a 100-unit syringe sits near the bottom of a barrel marked in 2-unit steps. The same dose on a 30-unit syringe, marked in 1-unit steps, spans two thirds of the barrel and is much harder to misread.
| Syringe | Holds | Typical markings | Best for |
|---|---|---|---|
| 30-unit | 0.3 mL | 1-unit steps | Small doses, the easiest to read accurately |
| 50-unit | 0.5 mL | 1-unit steps | Mid-range doses up to 50 units |
| 100-unit | 1 mL | 2-unit steps | Large volumes, hardest to read for small doses |
Safety tip: draw to the line, not between lines. If your dose lands between two markings, that is a signal to call your pharmacy, not to estimate.
Can You Inject Too Much by Converting Incorrectly?
Yes, and concentration is almost always how it happens. If you assume 2.5 mg/mL when your vial is actually 5 mg/mL, the same 40 units delivers 2 mg instead of 1 mg, which is double your dose. The medication did not change. The strength of the liquid did, and the syringe cannot tell the difference.
This is why the concentration on the label outranks every other number, including this page. An overdose of a GLP-1 typically means severe nausea, prolonged vomiting and dehydration, and it carries a risk of low blood sugar in people also taking insulin or a sulfonylurea. If you think you have injected too much, contact your prescriber or a poison information service straight away.
- Read the concentration on the label before every new vial, not just the first one
- Convert in both directions and check the two answers agree
- Confirm the units figure with the person who dispensed it before your first injection from a new vial
- Never reuse a units number from a forum, a friend, or an older vial
- If the dose does not land on a whole marking, stop and ask rather than rounding
Safety tip: the label wins. If your label and this calculator disagree, your label is right and something you entered here is wrong.
Compounded vs Brand-Name: Why Only One Needs Converting
Brand pens such as Ozempic, Wegovy, Mounjaro and Zepbound measure the dose for you. You dial or press in milligrams and never count units, so no conversion applies. Compounded medication is dispensed in vials at concentrations that vary by pharmacy, which is exactly why unit conversion exists at all.
That difference matters for safety, not just convenience. A pen removes the measurement step, and with it the most common way people get their dose wrong. A vial hands that step back to you, which is manageable, but only if you treat the concentration on the label as the source of truth every single time.
| Product | How the dose is measured | Do you count units? |
|---|---|---|
| Ozempic | Dial the pen in mg | No |
| Wegovy | Single-dose pen, fixed dose | No |
| Mounjaro | Single-dose pen or vial, full dose | No |
| Zepbound | Single-dose pen or vial, full dose | No |
| Compounded semaglutide | You draw it from a multi-dose vial | Yes |
| Compounded tirzepatide | You draw it from a multi-dose vial | Yes |
Semaglutide vs Tirzepatide: Units Are Not Comparable
Never compare units between the two drugs. Semaglutide is dosed in fractions of a milligram, up to 2.4 mg weekly, while tirzepatide runs from 2.5 mg to 15 mg. Compounded tirzepatide is also usually more concentrated. The result is that 20 units of one is nothing like 20 units of the other.
Units are a measure of volume, not of strength. They tell you how much liquid is in the barrel, and nothing at all about how much drug is in that liquid. Two people can inject the identical 20 units and receive completely different amounts of completely different medication.
Safety tip: whenever you see a units figure online, treat it as meaningless unless it comes with both the drug and the concentration.
GLP-1 Conversion Charts and Common Questions
Every answer below assumes a U-100 insulin syringe, where 100 units equals 1 mL. None of them mean anything without your concentration, so read your label first and use the chart that matches it.
mg to Units
The answer always depends on your concentration. Here is every common semaglutide dose at the three concentrations compounding pharmacies dispense most often, on a U-100 insulin syringe.
| Dose | At 1 mg/mL | At 2.5 mg/mL | At 5 mg/mL |
|---|---|---|---|
| 0.25 mg | 25 units | 10 units | 5 units |
| 0.5 mg | 50 units | 20 units | 10 units |
| 1 mg | 100 units | 40 units | 20 units |
| 1.7 mg | 170 units (2 syringes) | 68 units | 34 units |
| 2.4 mg | 240 units (3 syringes) | 96 units | 48 units |
| 5 mg (tirzepatide) | Not applicable | 200 units | 100 units |
- How many units is 0.25 mg?
- At 2.5 mg/mL, 0.25 mg is 10 units. At 5 mg/mL it is 5 units, and at 1 mg/mL it is 25 units. A 5-unit dose is very small to measure, so a 30-unit syringe is far safer than a 100-unit one here.
- How many units is 0.5 mg?
- At 2.5 mg/mL, 0.5 mg is 20 units. At 5 mg/mL it is 10 units, and at 1 mg/mL it is 50 units. This is why 0.5 mg equals 20 units only sometimes, and why the answer is worthless without a concentration attached.
- How many units is 1 mg?
- At 2.5 mg/mL, 1 mg is 40 units. At 5 mg/mL it is 20 units, and at 1 mg/mL it fills an entire 100-unit syringe. Same prescription, three different numbers on the barrel.
- How many units is 1.7 mg?
- At 2.5 mg/mL, 1.7 mg is 68 units, and at 5 mg/mL it is 34 units. At 1 mg/mL it would be 170 units, which does not fit in a single syringe, so a more concentrated vial is the correct answer rather than two injections.
- How many units is 2.4 mg?
- At 2.5 mg/mL, 2.4 mg is 96 units, which only just fits a 100-unit syringe. At 5 mg/mL it is 48 units, which is far more comfortable to draw. At the maintenance dose, concentration stops being a detail and starts deciding whether the dose fits at all.
- How many units is 5 mg of tirzepatide?
- At 5 mg/mL, 5 mg is 100 units, a full syringe. At 10 mg/mL it is 50 units, and at 20 mg/mL it is 25 units. Compounded tirzepatide is usually supplied concentrated for exactly this reason.
Units to mg
Working backwards from the syringe: multiply your units by the concentration, then divide by 100. The same units figure means a completely different dose at a different strength.
| Units | At 2.5 mg/mL | At 5 mg/mL | At 10 mg/mL |
|---|---|---|---|
| 10 units | 0.25 mg | 0.5 mg | 1 mg |
| 20 units | 0.5 mg | 1 mg | 2 mg |
| 30 units | 0.75 mg | 1.5 mg | 3 mg |
| 50 units | 1.25 mg | 2.5 mg | 5 mg |
| 100 units | 2.5 mg | 5 mg | 10 mg |
- 10 units equals how many mg?
- 0.25 mg at 2.5 mg/mL, 0.5 mg at 5 mg/mL, or 1 mg at 10 mg/mL. Ten units is a tenth of a millilitre, and how much medication sits in that tenth is entirely down to your vial.
- 20 units equals how many mg?
- 0.5 mg at 2.5 mg/mL, 1 mg at 5 mg/mL, or 2 mg at 10 mg/mL. If someone tells you 20 units is a standard dose, they are telling you about their vial, not yours.
- 30 units equals how many mg?
- 0.75 mg at 2.5 mg/mL, 1.5 mg at 5 mg/mL, or 3 mg at 10 mg/mL. Thirty units is 0.3 mL, which fills a 30-unit syringe exactly.
- 50 units equals how many mg?
- 1.25 mg at 2.5 mg/mL, 2.5 mg at 5 mg/mL, or 5 mg at 10 mg/mL. Note that 2.5 mg of semaglutide would be above the maximum approved weekly dose of 2.4 mg, which is the kind of mismatch worth catching before you inject.
- 100 units equals how many mg?
- 2.5 mg at 2.5 mg/mL, 5 mg at 5 mg/mL, or 10 mg at 10 mg/mL. One hundred units is a full millilitre, the entire barrel of a 100-unit syringe.
Concentration
- Why does concentration matter so much?
- Because it is the only thing standing between your dose in milligrams and the number on your syringe. Get it wrong and every unit you draw is wrong by the same factor. Assuming 2.5 mg/mL when the vial is 5 mg/mL doubles your dose.
- Why do pharmacies use different strengths?
- Compounding pharmacies formulate independently, so vial strength varies by pharmacy, batch and the dose range they expect you to need. Higher concentrations keep the injection volume small at maintenance doses. It is normal, and it is why you must re-check every new vial.
- What concentration is compounded semaglutide?
- Commonly 1, 2, 2.5 or 5 mg/mL, but there is no single standard and your pharmacy may use another. The only reliable source is the label on your own vial, never a chart, a forum or this page.
- What concentration is compounded tirzepatide?
- Often 5, 10 or 20 mg/mL, because tirzepatide doses run much higher than semaglutide and a dilute vial would make the injection volume impractical. As always, your label is the authority.
- What does mg/mL actually mean?
- How many milligrams of medication are dissolved in each millilitre of liquid. A 5 mg/mL vial holds 5 mg in every millilitre, so half a millilitre holds 2.5 mg. It describes the strength of the liquid, not the size of your dose.
Syringes
- What is a 30-unit syringe?
- A 0.3 mL insulin syringe, usually marked in 1-unit steps. It is the easiest to read for small GLP-1 doses because those few units are spread across the full length of the barrel.
- What is a 50-unit syringe?
- A 0.5 mL insulin syringe, typically marked in 1-unit steps. A comfortable middle ground for doses up to 50 units.
- What is a 100-unit syringe?
- A 1 mL insulin syringe, usually marked in 2-unit steps. It holds the most liquid but is the hardest to read precisely, so it is a poor choice for a 5 or 10-unit dose.
- How do I read an insulin syringe?
- The numbers on the barrel are units, not millilitres, and on a U-100 syringe 100 units equals 1 mL. Draw until the top of the plunger seal sits exactly on your line, at eye level, with no air bubble.
- Why did my pharmacy change my syringe?
- Usually because your dose or your concentration changed and the old barrel no longer fits it well. A dose that outgrows a 30-unit syringe needs a 50 or 100-unit one, and a smaller dose is safer to measure on a smaller barrel.
Injection Safety
- Can I inject too much?
- Yes, most often by using the wrong concentration in the conversion. Believing your vial is 2.5 mg/mL when it is 5 mg/mL doubles every dose you draw. Check the label before every new vial, and confirm your first draw with your pharmacist.
- What if I used the wrong concentration?
- Work out what you actually injected: units divided by 100, multiplied by the true concentration. If that is more than your prescribed dose, contact your prescriber or a poison information service now. Expect nausea and vomiting, watch for dehydration, and do not take your next dose until you have spoken to them.
- What if my dose lands between two markings?
- Do not estimate and do not round up. A dose that does not land on a line usually means the concentration and the syringe are mismatched, and the fix is a different vial or a different barrel. Ask your pharmacist.
- How do I double check my prescription?
- Convert in both directions. Take the units you plan to draw, convert them back to milligrams at your concentration, and confirm the result equals the dose your prescriber wrote. If the two disagree, do not inject.
- What should the pharmacy label tell me?
- The drug, the concentration in mg/mL, the total volume in the vial, your prescribed dose and how it is to be measured. If the concentration is missing from the label, call the pharmacy and ask for it before you inject.
By Medication
- How do I convert Ozempic to units?
- You do not. Ozempic is a pre-filled pen: you dial the dose in milligrams and the pen measures it. Never draw a pen into an insulin syringe. Unit conversion applies only to multi-dose vials.
- How do I convert Wegovy to units?
- There is nothing to convert. Wegovy comes as a single-dose pen that delivers its full fixed dose, so there is no measurement step and no units to count.
- How do I convert Mounjaro to units?
- Mounjaro single-dose pens and vials each contain one full dose, so a partial measurement is not part of the approved instructions. If you have been given a multi-dose compounded vial instead, convert using the concentration on that vial's label.
- How do I convert Zepbound to units?
- The same as Mounjaro: single-dose pens and vials deliver one full dose and need no conversion. Only compounded multi-dose vials require you to measure units yourself.
- How do I convert compounded medication?
- Divide your dose in mg by the concentration on your vial to get millilitres, then multiply by 100 for units on a U-100 syringe. This is the only category where you truly need this page.
Common Questions
- Why doesn't everyone use the same units?
- Because units measure liquid, not medication. The number of units you draw depends on how concentrated your vial is, and compounding pharmacies use different concentrations. There is no universal units figure for any GLP-1 dose.
- Can two people use different units for the same dose?
- Yes, and this is completely normal. One person drawing 40 units at 2.5 mg/mL and another drawing 20 units at 5 mg/mL are injecting the identical 1 mg dose.
- Why is my vial different from last time?
- Pharmacies change formulations, and a new prescription may be filled at a different strength. Never assume the new vial matches the old one. Read the concentration and redo the conversion before your first injection from it.
- Is 0.5 mg equal to 20 units?
- Only at 2.5 mg/mL. At 5 mg/mL, 0.5 mg is 10 units, and at 1 mg/mL it is 50 units. This exact question is the reason unit conversion errors happen, because the answer people remember was true for someone else's vial.
Where this fits in your GLP-1 journey
Each Calqulate tool answers one urgent question. Together they are a single operating system for your treatment.
Save your setup, then track every injection
This conversion solves the syringe in your hand today. Calqulate Vitals remembers your concentration and syringe, logs every injection you draw, charts your drug level between doses, and turns those weekly numbers into a picture of whether your treatment is actually working.
- Your concentration and syringe, saved
- Every injection on one timeline
- Drug-level curves between weekly shots
- Fat vs. muscle trend and plateau risk
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Sources and references
This page is built from public clinical guidance and peer-reviewed research. Always confirm decisions with a licensed clinician.
- 1.FDA: Medications containing semaglutide, including compounding information
- 2.FDA: Compounded tirzepatide, information for patients and providers
- 3.Ozempic (semaglutide) Prescribing Information (Novo Nordisk / FDA)
- 4.Wegovy (semaglutide) Prescribing Information (Novo Nordisk / FDA)
- 5.Mounjaro (tirzepatide) Prescribing Information (Eli Lilly / FDA)
- 6.Zepbound (tirzepatide) Prescribing Information (Eli Lilly / FDA)
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Medical Disclaimer: Calqulate Vitals provides educational information only. This converter performs arithmetic on numbers you enter and cannot see your vial, your syringe or your prescription. It is not medical advice, is not a dosing instruction, and does not replace your prescriber or pharmacist. Always confirm your concentration and your dose against the label and with the person who dispensed it. Never change your prescribed dose. If you believe you have injected the wrong amount, contact your prescriber or a poison information service immediately.
Tool Information
June 2026
Dr. Jaydeep Sanghani
Meet Akabari
Dr. Jaydeep Sanghani
MBBS, MD, DNB(Anaesth.), PDCC(CCM), DrNB(CCM)
AIIMS Bhubaneswar · AIIMS Rishikesh
Critical care specialist and anesthesiologist with advanced training from AIIMS. Reviews health calculators at Calqulate to ensure medical accuracy and evidence-based standards.
About the authors
Meet Akabari
·Co-Founder, Calqulate.net