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.
5 mg semaglutide vial examples
A 5 mg vial in 2 mL gives 2.5 mg/mL (2,500 mcg/mL). A 0.25 mg starting dose is 0.1 mL, or 10 units on a U-100 syringe.
A 0.5 mg dose at the same concentration is 0.2 mL, or 20 units.
- 5 mg / 2 mL = 2,500 mcg/mL
- 0.25 mg = 250 mcg → 0.1 mL = 10 units
- 0.5 mg = 500 mcg → 0.2 mL = 20 units
Why 5 mg is the common semaglutide starter vial
Most semaglutide titration schedules begin at 0.25 mg per week and step upward at 4-week intervals. A 5 mg vial holds about twenty 0.25 mg doses, which covers roughly five months of starter dosing — well beyond the beyond-use window of a single reconstituted vial.
In practice, a 5 mg vial usually carries you through the 0.25 mg and 0.5 mg titration weeks with one reconstitution. By the time doses move past 1 mg per week, the per-dose volume is large enough that the same vial empties faster, and many users transition to a 10 mg vial to reduce handling.
- Holds ~20 doses at the 0.25 mg starter step
- Most users complete weeks 1–8 of titration on a single 5 mg vial
- Plan a vial change once weekly doses pass 1 mg
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.