Quick math example
A 5 mg vial mixed with 2 mL gives 2.5 mg/mL. A 0.25 mg dose is 0.1 mL, which equals 10 units on a U-100 syringe.
10 mg semaglutide vial examples
A 10 mg vial in 2 mL gives 5 mg/mL (5,000 mcg/mL). A 0.25 mg dose is 0.05 mL, or 5 units on a U-100 syringe.
Because the concentration is double the 5 mg / 2 mL setup, every draw is half the volume for the same dose.
- 10 mg / 2 mL = 5,000 mcg/mL
- 0.25 mg = 250 mcg → 0.05 mL = 5 units
- 0.5 mg = 500 mcg → 0.1 mL = 10 units
When semaglutide users move to a 10 mg vial
The 10 mg vial typically becomes more practical once weekly doses reach 1 mg or above. At those doses, a 5 mg vial empties in about four weeks; a 10 mg vial doubles that runway without changing the math.
It is also the sensible size at the 1.7 mg and 2.4 mg maintenance doses. At 2.4 mg/week, a 5 mg vial holds barely two weeks of doses; a 10 mg vial holds about four. With BAC water at 2 mL (5 mg/mL), a 2.4 mg dose is 0.48 mL — about half a 1 mL syringe — which is easier to draw cleanly than at higher concentrations.
Smaller doses are still entirely workable from a 10 mg vial: at 5 mg/mL, a 0.25 mg starter draw is just 5 units, but the precision tolerance on a U-100 syringe at 5 units is tight.
- Practical once weekly doses reach 1 mg+
- Holds ~4 weeks of doses at 2.4 mg/week maintenance
- Trade-off: starter doses (0.25 mg = 5 units) are at the bottom of U-100 readability
How the semaglutide calculation works
The calculator first converts the vial amount from mg to mcg, then divides by the BAC water volume to find concentration. Your target dose is divided by that concentration to return mL and syringe units.
For GLP-1 compounds, small dose changes can meaningfully change the draw volume. Re-run the calculation whenever vial size, water amount, syringe type, or target dose changes.
- Concentration = vial mcg / water mL
- Dose volume = target dose mcg / concentration
- U-100 units = dose volume mL x 100
Semaglutide 5 mg vial with 2 mL example
A 5 mg semaglutide vial mixed with 2 mL gives a concentration of 2.5 mg/mL, or 2,500 mcg/mL.
A 0.25 mg dose is 250 mcg. At 2,500 mcg/mL, that dose is 0.1 mL, which equals 10 units on a U-100 syringe.
- 5 mg / 2 mL = 2.5 mg/mL
- 0.25 mg = 250 mcg
- 250 mcg / 2,500 mcg per mL = 0.1 mL = 10 U-100 units
Semaglutide 10 mg vial with 2 mL example
A 10 mg semaglutide vial mixed with 2 mL gives a concentration of 5 mg/mL, or 5,000 mcg/mL.
A 0.5 mg dose is 500 mcg. At 5,000 mcg/mL, that dose is 0.1 mL, which equals 10 U-100 units.
- 10 mg / 2 mL = 5 mg/mL
- 0.5 mg = 500 mcg
- 500 mcg / 5,000 mcg per mL = 0.1 mL = 10 U-100 units
Use with compounded or lyophilized vials
This page is intended for situations where you need to calculate a dose from a vial and diluent volume. Pre-filled commercial pens usually do not require this math.
Follow the label, pharmacy directions, and clinician instructions for storage, titration, and beyond-use dates.