Calculators / Retatrutide
Retatrutide reconstitution calculator
Enter your vial size, bacteriostatic water, and target dose — get the concentration, the exact U-100 syringe draw, and how many doses the vial holds. No account, no vendor ties, numbers never leave your browser.
How the math works
Three formulas, checked twice — the same engine that powers the Zyra Labs app:
- concentration (mg/mL) = peptide in vial (mg) ÷ BAC water (mL)
- draw volume (mL) = dose ÷ concentration
- U-100 units = draw volume (mL) × 100
Worked example: 20 mg Retatrutide + 2 mL water = 10 mg/mL. A 4 mg dose is then 4 mg ÷ 10 mg/mL = 0.4 mL = 40 units on a U-100 insulin syringe.
Retatrutide quick facts
| Half-life | ≈ 6 days |
|---|---|
| Typical route (published research) | SubQ · weekly |
| Common vial sizes | 5 mg · 10 mg · 20 mg · 30 mg |
Source: Retatrutide phase-2 pharmacokinetics (Jastreboff, NEJM 2023; half-life ≈6 days)
See also: Retatrutide half-life & clearance curve · Retatrutide dose charts (mg → units)
Frequently asked
How much BAC water should I add to a 20 mg Retatrutide vial?
There is no single correct amount — the water volume sets the concentration, not the dose. Adding 2 mL to 20 mg gives 10 mg/mL, which puts a 4 mg draw at 40 units on a U-100 insulin syringe. More water = larger, easier-to-measure draws; less water = smaller draws.
How many units is 4 mg of Retatrutide?
It depends entirely on your concentration. At 10 mg/mL (20 mg + 2 mL), 4 mg is 40 units on a U-100 syringe. Use the calculator above with your own vial and water volumes.
What is the half-life of Retatrutide?
Retatrutide's reported half-life is ≈ 6 days. See our cited half-life reference for the decay curve and clearance math.
Is this medical advice?
No. This calculator performs general arithmetic on values you enter, for research and educational purposes. It never recommends doses and we never answer sourcing questions.
Guides for Retatrutide
Track the whole protocol, not just one draw
The Zyra Labs app logs doses, schedules reminders, estimates medication levels from published half-lives, and keeps everything on your device. Free to start.
Zyra Labs is a research and educational utility. Nothing on this page is medical advice, a dosing recommendation, or an endorsement of any compound. We never sell or source compounds and refuse sourcing questions. Consult a qualified clinician for decisions about your health.