VialSemaglutide Reconstitution Calculator
Compounded semaglutide usually arrives as a lyophilized (powder) or liquid vial that you dilute before drawing with an insulin syringe. Two vials with the same strength can end up at completely different concentrations depending on how much diluent is added — so the math has to be re-run for every new vial. This free calculator does it in one tap.
Reference dose escalation, once weekly
The escalation below is the one published in the clinical labelling: a slow ramp to the maintenance dose, spaced out specifically to limit gastrointestinal side effects. Notice that the three lowest doses are initiation and escalation steps only — none of them is approved as a maintenance dose.
| Weekly dose | Published window | Role |
|---|---|---|
| 0.25 mg | Weeks 1–4 | Initiation only — not a maintenance dose |
| 0.5 mg | Weeks 5–8 | Escalation step |
| 1 mg | Weeks 9–12 | Escalation step |
| 1.7 mg | Weeks 13–16 | Lowest maintenance option |
| 2.4 mg | Week 17 on | Preferred maintenance dose |
This table describes the branded prescription medicine, not compounded or research material, which follows no approved schedule. Semaglutide is prescription-only: your own starting dose, pace of increase and maintenance dose are decided by your prescriber. VialDose is a unit converter — it cannot tell you what your dose should be.
Source: Wegovy dose escalation schedule, EMA public assessment report and Novo Nordisk product monograph (Table 2). Weekly doses above 2.4 mg are not recommended. Escalation may be delayed by 4 weeks if a step is not tolerated.
Worked example (round numbers)
A 5 mg vial mixed with 1 mL of diluent gives 5 mg/mL. If your prescribed dose is 0.25 mg, the draw is 0.25 ÷ 5 = 0.05 mL = 5 units on a 100U insulin syringe. Add 2 mL of diluent instead and the concentration drops to 2.5 mg/mL, so the same 0.25 mg becomes 0.25 ÷ 2.5 = 0.1 mL = 10 units — twice the volume, and markedly easier to measure.
Notice the direction: more diluent means a larger draw for the same dose. Small doses are easier to hit accurately at a lower concentration. This is exactly why the concentration step can't be skipped — same vial, same prescribed dose, completely different needle reading depending on how much water went in.
Three mistakes this calculator prevents
- Carrying over an old concentration. Every vial gets its own math. There is no "default" concentration.
- Unit confusion. mg and mcg differ by 1,000×. The tool converts between mg and mcg automatically and blocks any attempt to mix IU with mass units.
- Over-draws. If the target exceeds the vial contents or the draw exceeds the syringe capacity, the calculator blocks and explains — it never rounds a bad number into a plausible one.
Related guides
The VialDose app logs doses, rotates sites and counts down vial volume — private by design.