How the Retatrutide calculator works
There is no licensed product. Vials sold under this name are lyophilized powder labelled in milligrams. The quick-fill buttons in the calculator are the vial sizes Retatrutide is commonly labelled in (5 mg and 10 mg). If yours is different, type it in.
Amounts of Retatrutide are usually written in milligrams (mg), so the calculator opens in mg.
For a field-by-field walkthrough and a guide to syringe types, see the main peptide calculator.
Retatrutide concentration table
Each labelled vial size at the same three round water volumes used across this site. It shows how the arithmetic behaves and is not a suggestion of what to use.
| Vial | Water added | Concentration | Each mark holds |
|---|---|---|---|
| 5 mg vial | 1 mL | 5 mg/mL | 0.5 mg per 10 units |
| 5 mg vial | 2 mL | 2.5 mg/mL | 0.25 mg per 10 units |
| 5 mg vial | 3 mL | 1.67 mg/mL | 0.167 mg per 10 units |
| 10 mg vial | 1 mL | 10 mg/mL | 1 mg per 10 units |
| 10 mg vial | 2 mL | 5 mg/mL | 0.5 mg per 10 units |
| 10 mg vial | 3 mL | 3.33 mg/mL | 0.333 mg per 10 units |
Every row for a given vial holds the same total. To compare volumes for a specific reading, use the BAC water calculator.
The formula, step by step
The “Try example numbers” button uses one fixed rule on every page: the smallest labelled vial, 2 mL of water, and whatever amount lands on the 10-unit mark. The amount is a by-product of that rule and not a typical or suggested Retatrutide dose.
- Concentration: 5 mg ÷ 2 mL = 2.5 mg/mL.
- The 10-unit mark is 10 ÷ 100 = 0.1 mL, which holds 0.1 × 2.5 = 0.25 mg.
- Run it forwards to check: 0.25 mg ÷ 2.5 mg/mL = 0.1 mL, and 0.1 × 100 = 10 units.
Retatrutide: general reference
General educational reference for research purposes only. None of it is a recommendation, none of it is medical advice, and none of it is used by the calculator, which works only on the numbers you enter.
Retatrutide (LY3437943) is a single peptide that activates three receptors: GIP, GLP-1 and glucagon. It is being developed by Eli Lilly. It is an investigational medicine, which means it has not been approved anywhere.
Phase 2 results were published in the New England Journal of Medicine in 2023, and results from the phase 3 TRIUMPH programme were reported in 2026. Lilly has said it plans to apply to the FDA for approval in 2027.
Because it is unapproved, there is no licensed retatrutide product. Outside a clinical trial, a vial sold under that name is unregulated, and no regulator has checked what it contains.
- Class
- Triple GIP, GLP-1 and glucagon receptor agonist, investigational
- Group
- GLP-1 family
- Also known as
- LY3437943
- Molecular weight
- About 4,731 Da
- Half-life
- About 6 days. Published clinical-trial pharmacokinetics give a half-life of approximately 6 days.
- Regulatory status
- Investigational, not approved. Retatrutide is not approved by the FDA, the EMA or any other regulator. It is legally available only to people taking part in clinical trials.
- Labelled vial sizes
- 5 mg and 10 mg
Arithmetic slips to watch for with Retatrutide
There is no label to check against
With an approved medicine, the concentration is printed by the manufacturer and checked by a regulator. With an unlicensed vial the only figure is the seller’s stated milligrams. The calculator’s answer can only ever be as reliable as that number.
Units are not milligrams
Units measure volume. With 2 mL of water, 10 units holds 0.25 mg from a 5 mg vial but 0.5 mg from a 10 mg vial. A unit count does not carry over from one vial size to another.
Watch the decimal point
Amounts are written in milligrams with decimals, so a misplaced decimal point changes the amount by ten times. The “Show the math” panel prints every step.
What this page does not do
The calculator performs mathematical conversions only. It does not recommend, suggest or verify any Retatrutide dose or schedule, it does not say how much water to add, and it does not say what Retatrutide is for, whether it is safe, or whether it is legal where you live. It is not medical advice, diagnosis or treatment, and Peptrack does not sell, supply or endorse any substance.
Always confirm measurements with a licensed healthcare provider or pharmacist. See the full disclaimer.
Sources
- Jastreboff et al. (2023), triple-hormone-receptor agonist retatrutide for obesity, a phase 2 trial, New England Journal of Medicine
- BioPharma Dive: Lilly, with new data, to seek FDA approval of retatrutide
- ClinicalTrials.gov: TRIUMPH phase 3 study NCT05929066
Facts last checked: September 2026. Regulatory status changes, so check the regulator’s own pages for the current position.
