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How-to · reconstitution
Put 1 mL of bacteriostatic water into the 30 mg Retatrutide vial. That makes 30.00 mg/mL. A 2 mg dose is then 6.7 units on a U-100 syringe.
More water makes a weaker mix and a bigger draw. Less water makes a stronger mix and a smaller one. The amount of Retatrutide in the glass never changes. Only the number of marks it takes does.
Retatrutide is an experimental weekly injection being tested for weight loss. It acts on three hormone signals linked to appetite and metabolism.
| Water added | Concentration | Per U-100 unit | Example: 2 mg = |
|---|---|---|---|
| 1 mL | 30.00 mg/mL | 300 mcg | 6.7 units |
| 2 mL | 15.00 mg/mL | 150 mcg | 13.3 units |
Straight arithmetic: concentration = 30 mg ÷ water, and 1 U-100 unit = 0.01 mL. The example column shows the math at 2 mg; it is not a dose recommendation.
Which volume to use is a practical choice rather than a dose. Pick the one that puts your draw somewhere you can actually read it on the syringe. The flags in the last column mark where that fails. “Hard to measure” means the draw is too small to judge by eye. “Won’t fit” means it is bigger than one U-100 syringe holds.
The table above uses one worked example. These are the published quantities, converted into marks on a U-100 barrel at each water volume for a 30 mg vial. Where a quantity was never studied by injection, the row says so.
1–12 mg once weekly, under the skin.
| Water added | Concentration | Draw, low to high |
|---|---|---|
| 1 mL | 30.00 mg/mL | 3.3 to 40.0 units |
| 2 mL | 15.00 mg/mL | 6.7 to 80.0 units |
Human trialJastreboff AM et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. N Engl J Med 2023;389:514-26 (PMID 37366315) · retrieved 2026-08-12
The vial holds fifteen worked doses. Both water options put the draw between syringe lines, while the two smaller vial sizes land on whole units.
The vial size and worked amount do not divide evenly with either water option. The exact draw falls between syringe lines in both cases.
As a share of the draw the gap is small, because these draws are not tiny. The page still shows the exact figure rather than rounding for you, which is what makes the gap visible instead of assumed.
The vial divides into fifteen worked amounts, but no published source says how long the mixed solution keeps. Fifteen doses does not establish fifteen weeks of use.
Compounds with a labeled window get a wastage answer on these pages. This one gets a count and a caveat.
Read against the highest amounts the trials used, this vial holds only a few doses and the draws grow toward the middle of the barrel.
Read against the lowest arms it is more than a season’s worth of a compound no regulator anywhere has approved.
The table shows the offered water volumes. The calculator does the same arithmetic for any volume and any syringe, and shows its working line by line.
Open the Retatrutide calculator →The arithmetic on this page is only half the question. These are the pages that carry the other half.