Free tool · Compounded GLP-1 dosing
Your dose is in milligrams. Your syringe counts in units.
Enter your dose and the numbers on your vial. The tool shows how many units to draw.
Compounded GLP-1s are not FDA-approved
The FDA does not review compounded drugs for safety, effectiveness or quality before they are sold. This page is education, not medical advice. Follow your prescriber and pharmacist.
1. Your medication
The same drug as Zepbound and Mounjaro. Compounded versions are not FDA-approved.
2. Your dose, in milligrams
The number your prescriber gave you, like 2.5 mg. If you were only given units, ask for your dose in milligrams.
3. What your vial label says about the tirzepatide
Use the tirzepatide number only. Do not add in the additive.
4. Is anything else in the vial?
An additive does not change your units. Leave its strength blank if you do not know it.
Draw this much
2.5 mg of tirzepatide = 0.25 mL of liquid = 25 units on a U-100 syringe
Tap the syringe you have. The biggest number on the barrel is its size. This tool is for U-100 syringes. If yours does not say U-100, call your pharmacy.
2.5 mg ÷ 10 mg per mL = 0.25 mL. On a U-100 syringe, 1 mL is 100 units, so 0.25 mL is 25 units.
Each injection also has 0.125 mg of Vitamin B12.
If you find yourself drawing 250 units, stop. That is ten times your dose.
Were you told a number of units?
Enter it to see the dose in milligrams. This uses the vial strength above, 10 mg per mL.
Got a new vial?
A refill can be a different strength. Enter the new vial's tirzepatide strength to see if your units change. If the label shows total mg in total mL, divide the mg by the mL.
Zepbound and Mounjaro dose steps, from this vial
At 10 mg per mL. Check the strength on every new vial.
| Dose | mL | Units |
|---|---|---|
| 2.5 mg | 0.25 | 25 |
| 5 mg | 0.5 | 50 |
| 7.5 mg | 0.75 | 75 |
| 10 mg | 1 | 100 |
| 12.5 mg | 1.25 | 125 (more than 1 mL) |
| 15 mg | 1.5 | 150 (more than 1 mL) |
Latest guidance
The lowest dose that works
The American Diabetes Association's 2026 Standards of Care say to decide your long-term plan with your prescriber. One option it names is staying on the lowest effective dose to keep weight off. The Zepbound and Wegovy labels say to consider how well a dose works and how well you tolerate it when choosing a maintenance dose. A higher dose is not automatically better.
What a microdose looks like
Microdosing usually means taking less than the label's starting dose. Move the slider to see it from your vial.
30-unit syringe
1 mg is 10 units from this vial. The label's starting dose, 2.5 mg, is 25 units.
Doses below the label's starting dose are off-label. The Zepbound label says its 2.5 mg starting dose is for getting started and is not approved as a dose to stay on.
Some people try to take less from a brand-name pen by counting clicks. The Ozempic and Zepbound KwikPen instructions both say not to set a dose by counting clicks.
Small doses are small amounts of liquid, which are harder to measure. Talk to your prescriber before taking any dose that is not on your prescription.
Check before you inject
This tool only does math on the numbers you enter. Have your pharmacist confirm your units before you use a new vial.
Why milligrams become units
Milligrams are the medicine
Your dose in milligrams is the amount of drug. It is the number on brand-name labels, and the number that goes up when your dose goes up.
Units are the liquid
Compounded vials are drawn with an insulin syringe, which is marked in units. On a U-100 syringe, 100 units is 1 mL. A unit measures liquid, not medicine.
The label connects them
The strength on your vial, in mg per mL, turns milligrams into units. Strengths differ between pharmacies, and one pharmacy can sell more than one. The same 2.5 mg is 25 units from a 10 mg/mL vial, about 31 units from 8 mg/mL, and 12.5 units from 20 mg/mL. A number of units means nothing without the strength.
Additives
Some compounded vials also contain another ingredient, like vitamin B12. It is mixed into the same liquid, so it does not change your units. Use the GLP-1's strength, not the additive's.
How brand-name pens compare
Brand-name pens measure the dose for you. With a compounded vial, you measure it yourself.
Single-dose pens: Zepbound, Wegovy
One pen, one dose, already set. You press it to your skin and it injects. Zepbound: unlock, press and hold up to 10 seconds, listen for two clicks, and check that the gray plunger shows. Wegovy: press firmly, listen for two clicks, and hold until the yellow bar stops moving.
Multi-dose pens: Ozempic, Zepbound KwikPen
One pen holds several doses. You turn a knob to set each one. The Ozempic pen shows your dose in milligrams. The Zepbound KwikPen holds four doses, and you turn the knob until it stops. Neither is set by counting clicks.
Brand-name vials: Zepbound
Single-dose vials hold 0.5 mL at every strength. You draw the whole amount with a syringe. The liquid stays the same and the strength changes.
Compounded vials
One strength, many doses. You measure each dose in units, and the number depends on the vial. The strength stays the same and the liquid changes.
What has gone wrong
In July 2024 the FDA reported dosing errors with compounded semaglutide vials. Patients took 5 to 20 times their dose. One patient told to take 5 units took 50. One prescriber meant 5 units and wrote 25. Some patients needed hospital care. In 2023 a poison control center reported three cases, and two of those people took ten times their dose.
Before every new vial
- Read the strength on the label. It can change between refills.
- Check that your syringe says U-100.
- Get your dose in milligrams and units, in writing.
- If your units do not match this tool, ask your pharmacy before you inject.
- Put used syringes straight into a sharps container. How to get rid of sharps safely.
Sources
7 references
- US Food and Drug Administration. FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products. July 26, 2024. fda.gov. The 5 to 20 times overdoses, the 5-unit (0.05 mL) dose taken as 50 units, the prescriber who wrote 25 units for 5, hospital care, strengths that vary between compounders, and that compounded drugs are not FDA-reviewed for safety, effectiveness or quality.
- Lambson JE, Flegal SC, Johnson AR. Administration errors of compounded semaglutide reported to a poison control center: case series. Journal of the American Pharmacists Association. 2023;63(5):1643–1645. doi:10.1016/j.japh.2023.06.017. Three cases, two of them tenfold dosing errors.
- Zepbound (tirzepatide) Prescribing Information. Eli Lilly and Company. DailyMed. The 2.5 to 15 mg dose steps, the 2.5 mg starting dose not approved for maintenance, the 0.5 mL single-dose vials, and the Instructions for Use for the single-dose pen and the KwikPen, including not counting clicks.
- Mounjaro (tirzepatide) Prescribing Information. Eli Lilly and Company. DailyMed. The same 2.5 to 15 mg dose steps.
- Wegovy (semaglutide) Prescribing Information. Novo Nordisk. DailyMed. The 0.25, 0.5, 1, 1.7 and 2.4 mg steps, the 7.2 mg dose, considering response and tolerability when choosing a maintenance dose, and the pen Instructions for Use.
- Ozempic (semaglutide) injection Prescribing Information. Novo Nordisk. DailyMed. The 2 mg step and the pen Instructions for Use, including not setting a dose by counting clicks.
- American Diabetes Association Professional Practice Committee for Diabetes. 8. Obesity and weight management for the prevention and treatment of diabetes: Standards of Care in Diabetes 2026. Diabetes Care. 2026;49(Suppl 1):S166–S182. doi:10.2337/dc26-S008. Deciding the long-term plan together, including staying on the lowest effective dose to keep weight off.
Coaching
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