Calculator
Retatrutide Dosage Calculator
The arithmetic on this page is the same arithmetic as any other reconstitution: milligrams in the vial, milliliters of water, and the dose you have already decided on. What is different about retatrutide is everything around the arithmetic, so that comes first.
Before you calculate anything, three things about retatrutide
- It is not approved. A search of the FDA's drug approval database returns no match for retatrutide, for any indication, in any country the agency covers. Nothing sold under that name has been through an approval.
- The published evidence in obesity is one trial of 338 people. Four phase 3 obesity trials have since finished — 2,335 participants, 1,152, 1,946 and 445 — and not one has released a result, in a journal or on the trial registry. The −24.2% figure everyone quotes is from that 338-person phase 2 at 48 weeks. The only phase 3 that has published, in type 2 diabetes, came in at −15.3%.
- A DailyMed listing is not an approval. Retatrutide does appear there, and sellers cite that as legitimacy. Every one of those records is a label submitted by a single cross-border e-commerce company — including one for a transdermal 'slimming patch' claiming to deliver a peptide through the skin. Anyone can file a listing; nobody checked it.
Read the full Retatrutide evidence page for the trial data and sourcing behind these facts.
This tool does not recommend a dose
Enter your own numbers
Calculator
Total peptide mass printed on the vial label.
How much diluent you mixed into the vial.
Nothing here is suggested — this is the dose you have already decided on.
Enter all three numbers above — vial strength, water added, and your target dose, each greater than zero — to see the result.
Read this too
What this calculator does not tell you
It does not know your real concentration
It does not know whether a quantity is appropriate
It does not verify sterility, purity, or legality
The arithmetic
How the math works
Three numbers go in: the peptide amount printed on the vial (mg), the bacteriostatic water you mixed into it (mL), and the dose you have already decided on (mg).
Concentration = vial strength (mg) ÷ water added (mL), in milligrams per milliliter.
Syringe units = (target dose (mg) ÷ concentration (mg/mL)) × 100 — because a standard insulin syringe is marked so that 100 units equal 1 mL. That assumption is fixed, shown on the page, and never hidden in the arithmetic.
For the longer version, including where a straightforward division goes wrong, read the full worked example, checked against the label.
Glossary
Key terms
- Reconstitution
- Adding a liquid — usually bacteriostatic water — to a freeze-dried (lyophilized) peptide powder to turn it into an injectable solution.
- Concentration (mg/mL)
- How much peptide sits in each milliliter of the mixed solution — the exchange rate between a mass and a volume.
- Bacteriostatic water
- Sterile water with a small amount of benzyl alcohol added as a preservative, which lets a multi-dose vial be entered repeatedly rather than used once and discarded.
- Syringe units (U-100)
- The markings on a standard U-100 insulin syringe, where 100 units equal 1 milliliter. A different syringe, such as a U-40, uses a different scale entirely.
- Draw volume
- The volume of mixed solution — in milliliters — that contains your target dose. This is what the syringe-unit figure is converted from.
- Vial strength
- The total mass of peptide printed on the vial's label, in milligrams — before any water is added.
Questions
Frequently asked questions
What is the correct retatrutide dose?
This calculator does not answer that, and no honest page can. The published trials tested 1 mg, 4 mg, 8 mg and 12 mg weekly in a 338-person phase 2, and escalated gradually because the gastrointestinal effects scaled with the amount given. That is a description of what a trial did under supervision, not a schedule for anyone to follow. The tool converts a dose you have already decided on with a clinician into syringe units; it has no dose of its own to offer.
Is retatrutide legal to buy?
It has no FDA approval for any indication, so there is no legitimate prescription route to it. What is sold online as retatrutide is sold for research use, which is a legal category describing what a seller may ship without a prescription — not a purity standard, not a quality guarantee, and not a signal that approval is coming.
Why does retatrutide show up on DailyMed if it is not approved?
Because DailyMed publishes labels that companies submit, and submission is not review. The retatrutide records there come from one cross-border e-commerce labeler, and the set includes a microneedle 'slimming patch.' Presence in a federal database is the exact signal a seller wants you to misread, which is why it is worth checking who filed the label.
How many units is a retatrutide dose?
That depends entirely on how much water you mixed into the vial, which is why it cannot be answered as a fixed number. A 10 mg vial in 2 mL of bacteriostatic water is 5 mg/mL, so a 2.5 mg dose is 0.5 mL, which is 50 units on a standard U-100 syringe. Change the water volume and every unit figure changes with it. Enter your own numbers above.
Medical disclaimer: This content is for general educational purposes only and is not medical advice, diagnosis, or treatment. Always consult a licensed healthcare professional before starting, stopping, or changing any treatment.