Retatrutide Dosage Calculator

How to Use the Retatrutide Dosage Calculator

The calculator turns four inputs into a clean result. Select the amount of retatrutide in your vial, the bacteriostatic water you added to reconstitute it, your target dose in milligrams, and your syringe size. It returns the vial concentration, the exact units to draw on a U-100 insulin syringe, and how many doses the vial holds.

Retatrutide is measured in milligrams, so most targets enter directly. Change any value and the result updates instantly, so you can compare a 10 mg and a 20 mg vial, or 1 ml against 2 ml of water, without redoing the arithmetic.

How This Calculator Works

The calculator runs three steps, and you can check each one by hand.

Concentration = vial amount ÷ water added. Draw volume = your target dose ÷ concentration. Syringe units = draw volume × 100 on a U-100 insulin syringe.

Worked in arbitrary numbers: say your target is 2 mg, drawn from a 10 mg vial reconstituted with 2 ml of bacteriostatic water. Concentration is 10 mg ÷ 2 ml, which is 5 mg/ml. Draw volume is 2 mg ÷ 5 mg/ml, which is 0.4 ml. Units are 0.4 ml × 100, which is 40 units.

The 2 mg here is an example input to show the arithmetic, not a suggested dose.

Every figure above appears in the result box, concentration, draw volume, and units side by side, so you can verify the conversion yourself rather than trusting a single number.

Retatrutide research vials commonly come in 5 mg, 10 mg, 15 mg, and 20 mg sizes, and the vial size drives every downstream number. Concentration is the peptide amount divided by the bacteriostatic water you add. A 10 mg vial reconstituted with 2 ml of water gives 5 mg/ml, while the same 10 mg vial in 1 ml gives 10 mg/ml. The more water you add, the more dilute the solution and the larger the volume you draw for the same dose, which is why a thinner mix is easier to measure at low doses and a stronger mix keeps the draw small at high doses.

Enter your real vial size and water volume, since changing either one changes the units you draw. For the reconstitution math common to every peptide, see the main peptide calculator.

Retatrutide is dosed in milligrams, given once weekly, and stepped up gradually rather than started at full strength. Because it is investigational, there is no approved dose, only what researchers have tested. The Phase 2 trial published in the New England Journal of Medicine studied a weekly range reaching 12 mg at the top end, escalated over several weeks to reduce gastrointestinal effects. That is a description of trial design, not a usage guide, and this calculator does not select any figure for you. It converts a target you already have. One consequence worth planning for: as the target rises across a titration, the draw volume grows, and a high dose from a dilute vial can exceed a single syringe. For what the trials actually found, see the retatrutide peptide guide.

Retatrutide, known in research as LY3437943, is an investigational peptide developed by Eli Lilly that acts on three hormone receptors at once, GLP-1, GIP, and glucagon. That triple-agonist design is what separates it from the single and dual agonists in the weight-loss class. It is not FDA approved and remains in late-stage clinical trials. This page is the calculation tool. For what retatrutide is, how the three-receptor mechanism works, what the trials showed, its side effects, and how it compares to semaglutide and tirzepatide, see the retatrutide peptide guide.

The calculator's accuracy depends entirely on your inputs, and retatrutide has one risk built into how it is used. Because the dose climbs across a titration, the same vial and water combination that gives a small, easy draw at the start can push past a single syringe near the top of the range. Two habits reduce the risk. First, confirm the vial size printed on your product against what you enter, since a 10 mg vial entered as 20 mg halves every dose you draw. Second, if the calculator flags that your draw exceeds the syringe, either use a larger syringe, reconstitute with less water for a stronger solution, or split the dose across two injections at separate sites. The result box shows the concentration and the exact units together, so you can check the volume against the math.

This calculation gives you the exact volume to draw, but accuracy depends on the right supplies and correct reconstitution. Before measuring a dose, review how to take a peptide shot for syringe setup and injection technique, and how to reconstitute peptides for the mixing steps. For the compound itself, see the retatrutide peptide guide.

Retatrutide Dosage Calculator FAQ