If you use a reconstituted vial of semaglutide, tirzepatide, or another GLP-1, this free calculator converts your prescribed dose in milligrams into the number of units to draw on a standard U-100 insulin syringe — instantly, with the concentration and doses-per-vial worked out for you.
Math: concentration = vial mg ÷ water mL; volume = dose mg ÷ concentration; units = volume mL × 100 (a U-100 syringe has 100 units per mL). Always confirm dosing with your prescriber and the instructions that came with your medication. This tool does not account for pre-filled fixed-dose pens.
Important: This tool is for educational use to check arithmetic only. Dosing GLP-1 medications incorrectly can be dangerous. Always follow the exact instructions from your prescriber and pharmacist, and never change your dose without medical guidance.
Converting a milligram dose into syringe units takes three steps:
The calculator above does this automatically and also flags doses that won't fit in a 1 mL syringe or exceed the liquid in your vial, which usually signals a mixing error to re-check.
First find the concentration of your reconstituted vial: divide the total mg of peptide by the mL of bacteriostatic water you added (mg ÷ mL = mg/mL). Then divide your prescribed dose by that concentration to get the volume in mL, and multiply by 100 to get units on a standard U-100 insulin syringe. For example, a 5 mg vial mixed with 2 mL of water is 2.5 mg/mL; a 0.25 mg dose is 0.1 mL, which is 10 units.
A standard U-100 insulin syringe is marked in units, where 100 units equals 1 mL. So 10 units = 0.1 mL and 50 units = 0.5 mL. GLP-1 doses drawn from a reconstituted vial are commonly measured this way because the volumes are very small.
No — the branded pens (Wegovy, Ozempic, Mounjaro, Zepbound) are pre-filled, fixed-dose devices, so you don't draw units yourself. This calculator is for reconstituted vials (often compounded semaglutide or tirzepatide) where you measure each dose with an insulin syringe. For projected weight loss with the branded medications, use our medication calculators below.
No. This is an educational tool to double-check the arithmetic. Always follow the exact dosing, reconstitution, and injection instructions provided by your prescriber and pharmacist. If a result looks unexpected, do not inject — confirm with your healthcare provider first.