0.25 mg of semaglutide is 10 units at 2.5 mg/mL, 5 units at 5 mg/mL, or 2.5 units at 10 mg/mL, because units depend on your vial’s concentration, not on the dose alone: draw volume = 0.25 mg / concentration, and units on U-100 = draw volume x 100. Which of those applies depends on how your vial was reconstituted.
How many units is 0.25 mg of semaglutide?
draw volume = 0.25 mg / concentration in mg per mL
units on U-100 = draw volume x 100Three worked examples, all for the same 0.25 mg:
- A 5 mg vial in 2 mL is 2.5 mg per mL. 0.25 / 2.5 = 0.1 mL, so 10 units.
- A 10 mg vial in 2 mL is 5 mg per mL. 0.25 / 5 = 0.05 mL, so 5 units.
- A 10 mg vial in 1 mL is 10 mg per mL. 0.25 / 10 = 0.025 mL, so 2.5 units.
The third case is worth pausing on. Two and a half units is a small reading, and a half unit either way is a twenty percent difference in what you drew. The semaglutide calculator flags a draw that small, because the arithmetic is fine and the measurement is not.
If your vial has a printed concentration in mg per mL rather than a dry weight, skip the reconstitution step entirely: enter that concentration as if the vial were one millilitre at that strength, and the same division applies.
Where 0.25 mg comes from
Zero point two five milligrams once weekly is the starting step printed on the US labelling for both branded semaglutide products, held for four weeks before any increase. The Ozempic label then moves to 0.5 mg once weekly, with a maximum of 2 mg once weekly. The Wegovy label steps 0.25, 0.5, 1, 1.7 and 2.4 mg, four weeks at each step. Both schedules, with their sources, are reproduced on the semaglutide page, and reading a GLP-1 titration schedule explains how to read a ladder like that without turning it into advice.
This site does not tell you which schedule applies to you, and a compounded vial is not the labelled product. The arithmetic is the same; the decision is not arithmetic.
Check it the other way round
The fastest sanity check is micrograms per unit. At 5 mg per mL, a U-100 unit carries 50 mcg. A 0.25 mg dose is 250 mcg, and 250 divided by 50 is 5 units, which matches the second example above. Two routes to the same number is how you catch a slipped decimal point, and it is the method described in how to convert mg to units.
In short: 0.25 mg of semaglutide converts to units by dividing by your vial’s concentration in mg per mL, then multiplying by 100 on a U-100 syringe, which is why the same 0.25 mg dose can read as 2.5, 5 or 10 units.