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Semaglutide & tirzepatide calculator: mg to mL to units
Got a vial and a dose in mg, but your syringe says "units"? Plug in your own numbers and see the exact math, step by step. No guessing, no mix-ups.
Your result and the full math will show here.
Always follow your prescriber and pharmacist; double-check with them. This tool does math only. It never suggests a dose, and it's for U-100 insulin syringes only (100 units = 1 mL).
The math, plainly
- Concentration (mg/mL) = total mg in the vial ÷ mL of liquid in it. If your label already says mg/mL, use that.
- mL to draw = your prescribed dose in mg ÷ concentration in mg/mL.
- Units on a U-100 syringe = mL × 100.
That's it. Three steps, and the concentration is the one that matters most: the same mg dose is a different number of units in a different-strength vial.
Why people mix these up
Milligrams (mg) measure the drug. Milliliters (mL) and syringe "units" measure liquid. The FDA has received reports of dosing errors with compounded semaglutide where people confused mg, mL and units, including patients told to draw 5 units (0.05 mL) on a U-100 syringe who drew 50 units instead. FDA says compounded concentrations can vary, even from one compounder, and that patients should talk with their prescriber or compounder about how to measure their dose. The FDA-approved pens (Ozempic, Wegovy) are dosed in mg and come prefilled.
New to these drugs? Read the semaglutide guide and the tirzepatide guide for label dosing straight from the FDA, or compare all four GLP-1s. Buying from a pharmacy you don't know? See how to tell if a source is legit.
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Units calculator FAQ
How many units is 1 mL on an insulin syringe?
On a U-100 insulin syringe, 1 mL is 100 units, so 0.1 mL is 10 units and 0.01 mL is 1 unit. 'Units' on the syringe are a measure of volume, not of drug.
How do I convert mg to units?
Divide your prescribed dose in mg by your vial's concentration in mg per mL to get mL. Multiply mL by 100 to get units on a U-100 syringe. The concentration is the number that changes everything, so take it from your own vial label or pharmacy.
Why does the same dose come out to different units?
Because concentrations vary. FDA notes that compounded semaglutide can come in different concentrations, even from the same compounder, so the same mg dose can be a different number of units.
Does this calculator tell me what dose to take?
No. It only converts the dose your prescriber gave you. It never suggests a dose. Always follow your prescriber and pharmacist and double-check with them.
Sources: FDA alert on compounded semaglutide dosing errors; FDA's concerns with unapproved GLP-1 drugs.
Not medical advice. Education only. We don't sell anything or tell you what to take. Label doses are there so you can follow along with your prescriber. Talk to a licensed clinician about your health.