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GLP-1 Dose Calculator: mg → units

Compounded semaglutide and tirzepatide come in vials, and the dose is prescribed in milligrams (mg) — but you draw it up in units on an insulin syringe. This converts one to the other using your vial’s concentration. It is a math aid only: your prescriber and the vial label are the source of truth.

mg

The milligram amount your prescriber told you to take (e.g. 0.25 mg, 2.5 mg).

mg/mL
Not sure of your concentration?

It’s printed on your vial label. If the label lists a total amount and a total volume instead — for example “10 mg / 2 mL” — divide the mg by the mL: 10 ÷ 2 = 5 mg/mL. If you can’t find it or aren’t sure, stop and ask your pharmacy — do not guess.

How the conversion works

Insulin syringes are marked in units, where a U-100 syringe holds 100 units per millilitre. So to turn a milligram dose into units you divide the dose by the vial’s concentration (to get millilitres), then multiply by 100:

units = (dose in mg ÷ concentration in mg/mL) × 100

Example: a 0.25 mg dose from a 2.5 mg/mL vial is 0.25 ÷ 2.5 = 0.1 mL = 10 units. The only variable that changes the answer is your vial’s concentration — which is exactly why you must read it off your own label rather than assume.

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