Reconstitution chart: 5 mg vial
| BAC water added | Concentration | Draw for 0.25 mg dose | Draw for 0.5 mg dose |
|---|---|---|---|
| 1 mL | 5,000 mcg/mL | 5 units | 10 units |
| 1.5 mL | 3,333 mcg/mL | 7.5 units | 15 units |
| 2 mL | 2,500 mcg/mL | 10 units | 20 units |
| 2.5 mL | 2,000 mcg/mL | 12.5 units | 25 units |
Draws are U-100 insulin syringe units (100 units = 1 mL). Formula: dose in mcg ÷ (vial mcg ÷ water mL) × 100. The calculator above handles any other combination.
About Semaglutide
Semaglutide is a GLP-1 receptor agonist and the active ingredient in Ozempic, Wegovy, and Rybelsus from Novo Nordisk. The injectable brand products are FDA approved for type 2 diabetes and chronic weight management, and they ship as pre-filled pens with the dose already measured for you. Reconstitution math only enters the picture with compounded or research-grade semaglutide, which arrives as a freeze-dried powder in a plain glass vial with no markings.
The FDA-approved products follow a slow ramp. Wegovy starts at 0.25 mg once weekly and steps up through 0.5 mg, 1 mg, and 1.7 mg before reaching the 2.4 mg maintenance dose, with about a month at each step. That schedule exists because the common side effects, mostly nausea and digestive upset, hit hardest when the dose climbs too fast. This calculator never picks your dose. It only converts the dose you and your prescriber settled on into a syringe draw.
Semaglutide has a half-life of about one week, which is why it is injected once weekly. It is also the compound where dosing mistakes are best documented: the FDA has logged reports of people taking 5 to 20 times the intended amount of compounded semaglutide because of confusion between mg, mcg, and mL. That is exactly the error the step-by-step math display above is built to catch. Keep reconstituted vials in the refrigerator.
Quick facts
- Status: FDA approved as Ozempic, Wegovy, Rybelsus (compounded and research vials are a separate, unapproved supply chain)
- Half-life: about 7 days, injected once weekly
- Common gray-market vial sizes: 2, 5, and 10 mg
- Storage: refrigerate after reconstitution