📊 Ozempic (Semaglutide) Dosage Calculator
Select your titration phase, vial size, and bacteriostatic water volume — concentration, draw volume, and syringe units calculated instantly for each weekly injection.
Semaglutide Reconstitution & Dose Calculator
Ozempic (semaglutide) is a GLP-1 receptor agonist used clinically for type 2 diabetes management and, at higher doses (Wegovy formulation), for chronic weight management. Compounded or research-grade semaglutide is supplied as a lyophilised powder requiring reconstitution with bacteriostatic water before subcutaneous injection. The titration schedule follows a deliberate step-up protocol — starting at 0.25 mg per week and escalating over 12+ weeks — specifically to minimise gastrointestinal side effects as the body adapts to GLP-1 signalling.
This calculator handles the conversion maths in real time. Select your current titration phase, enter your vial size and BAC water volume, choose your syringe — and the calculator returns your exact concentration, draw volume in mL, and the precise unit mark on a U-100 insulin syringe.
You have a 5 mg semaglutide vial, add 2 mL BAC water, and want the Phase 2 dose of 0.5 mg (500 mcg) on a 0.5 mL U-100 syringe.
- Concentration = (5 × 1,000) ÷ 2 = 2,500 mcg/mL
- Volume = 500 ÷ 2,500 = 0.2 mL
- U-100 draw = 0.2 × 100 = pull to the 20-unit mark
- Doses per vial = floor(5,000 ÷ 500) = 10 doses
Select your current titration phase
Semaglutide vial size
Bacteriostatic water added
What syringe volume are you using?
Select your phase and inputs above to generate your draw guide.
Standard 4-phase titration protocol with 4 weeks per phase. Escalation may be paused if tolerability is a concern — individual GI response varies significantly between patients.
| Phase | Weeks | Weekly Dose | Injections | 2 mg Vials | 5 mg Vials | Draw (2 mL BAC / 5 mg vial) |
|---|---|---|---|---|---|---|
| Phase 1 | 1–4 | 0.25 mg (250 mcg) | 4 | 1 | 1 | 10 units U-100 |
| Phase 2 | 5–8 | 0.5 mg (500 mcg) | 4 | 1 | 1 | 20 units U-100 |
| Phase 3 | 9–12 | 1 mg (1,000 mcg) | 4 | 2 | 1 | 40 units U-100 |
| Phase 4 | 13+ | 2 mg (2,000 mcg) | ongoing | 4+ | 2+ | 80 units U-100 |
Draw values above use a 5 mg vial + 2 mL BAC water = 2,500 mcg/mL. Use the calculator above for exact values based on your specific vial and reconstitution volume.
Ozempic Calculator — Frequently Asked Questions
How do I reconstitute compounded semaglutide?
Draw your chosen bacteriostatic water volume into an insulin syringe or sterile draw syringe. Insert the needle into the lyophilised powder vial and inject slowly against the glass wall — never directly onto the powder. Gently swirl the vial until the powder dissolves completely; the resulting solution should be clear and colourless. Never shake the vial as agitation can degrade the peptide. Label the vial immediately with the reconstitution date and store refrigerated at 2–8°C. Use within 28 days.
Why does semaglutide titration start at 0.25 mg rather than the therapeutic dose?
The 0.25 mg Phase 1 dose is a tolerability step, not a clinically therapeutic dose. Semaglutide significantly slows gastric emptying; jumping straight to 0.5 mg or higher commonly causes severe nausea, vomiting, and gastroparesis symptoms. Four weeks at 0.25 mg allows GI motility receptors to adapt, making subsequent higher doses far better tolerated. Some protocols extend Phase 1 to 8 weeks if tolerability remains suboptimal at the end of week 4.
How much BAC water should I use to reconstitute a semaglutide vial?
Target a draw volume that is easy to measure accurately — ideally between 10 and 40 units on your syringe. For a 5 mg vial at the Phase 2 dose of 0.5 mg: 2 mL BAC water gives 2,500 mcg/mL, producing a 20-unit draw — comfortable and precise. Using only 1 mL doubles concentration to 5,000 mcg/mL, halving the draw to 10 units — at this small volume, even a 1-unit measurement error creates a 10% dose variance. More BAC water → lower concentration → larger, more accurate draws. Use the calculator above to find the volume that suits your dose and syringe.
What is the difference between Ozempic, Wegovy, and compounded semaglutide?
All three contain semaglutide but differ in indication, approved dose ceiling, and formulation. Ozempic (0.5–2 mg/week) is FDA-approved for type 2 diabetes management. Wegovy (0.25–2.4 mg/week) is the same molecule in a higher-dose formulation approved specifically for chronic weight management. Compounded semaglutide is produced by licensed compounding pharmacies as a research-grade lyophilised vial; it is not FDA-approved but uses the same active compound. The reconstitution maths in this calculator apply identically to all three when supplied as a powder vial.
How long does a reconstituted semaglutide vial last?
Once reconstituted with bacteriostatic water and stored refrigerated at 2–8°C, the solution is stable for 28 days — the standard window for BAC water-preserved peptides. At Phase 1 (0.25 mg/week), a 5 mg vial yields 20 doses but you have only 28 days to use them, meaning multiple vials are needed for a full phase unless dose frequency is higher. At Phase 2 (0.5 mg/week), 4 doses per vial fits neatly within 28 days. Always label and date every vial on reconstitution day — using expired solution is a research integrity risk.
What syringe needle gauge and length are recommended for semaglutide injections?
For subcutaneous (SC) self-injection, 29–31 gauge needles at 4 mm or 6 mm (5/16") length are standard for insulin-style syringes. Preferred injection sites include the abdomen (at least 2 inches from the navel), the outer thigh, and the upper arm. Rotate sites every injection to prevent lipodystrophy and localised tissue thickening. Use a fresh needle for each injection — reusing causes tip burring, increased pain, and elevated infection risk. Dispose of all sharps immediately in a proper sharps container.