Retatrutide 15 mg Vial: Reconstitution and Dosing Chart

How much bacteriostatic water to add to a 15 mg vial of Retatrutide, the concentration you get, and a full dose-to-units chart.

Medically reviewed by Juan Pablo Frías, MD · 3 Oct 2026 · DisclosureGLP-1 / GIP / glucagon triple agonistUpdated 3 Oct 2026

Vial size: 15 mg
With 2 mL water: 7.5 mg/mL; common choice
10 units contain: 0.75 mg; at 2 mL, U-100
Whole vial: 200 units; 2 mL on a U-100 scale

How much water to add

Bacteriostatic water only changes the concentration, not the amount of Retatrutide in the vial. More water means more units per dose (easier to read), less water means fewer.

Retatrutide 15 mg vial: concentration by water added
Water added	Concentration	10 units contain	1 mg is	Whole vial
1 mL	15 mg/mL	1.5 mg	6.7 u	100 u
2 mL	7.5 mg/mL	0.75 mg	13.3 u	200 u
2.5 mL	6 mg/mL	0.6 mg	16.7 u	250 u
3 mL	5 mg/mL	0.5 mg	20 u	300 u

Calculator and full dosing table

Preset to the 15 mg vial. Change any value; the table below the result updates with it.

1Vial size

2Bacteriostatic water added

3Dose per injection

4Syringe (U-100)

Draw to

26.67units

= 0.27 mL on a 1 mL U-100 insulin syringe

15 mg vial2 mL water2 mg dose

Concentration: 7.5 mg/mL
Doses per vial: 7
Weeks (1 dose/wk): 7

Math only. It does not recommend a dose.

Dosing table for a 15 mg vial

Syringe units (U-100) for each dose, by how much bacteriostatic water you add.

Retatrutide: U-100 syringe units per dose for a 15 mg vial
Dose	1 mL water	2 mL water	2.5 mL water	3 mL water
0.5 mg	3.33	6.67	8.33	10
1 mg	6.67	13.33	16.67	20
2 mg	13.33	26.67	33.33	40
4 mg	26.67	53.33	66.67	80
6 mg	40	80	100	120
8 mg	53.33	106.67	133.33	160
10 mg	66.67	133.33	166.67	200
12 mg	80	160	200	240

How the math works

Concentration is the vial's milligrams divided by the water you add. Volume to draw is your dose divided by that concentration. On a U-100 syringe, 1 mL is 100 units, so units = mL × 100.

15 mg ÷ 2 mL = 7.5 mg/mL
2 mg ÷ 7.5 mg/mL = 0.27 mL
0.27 mL × 100 = 26.67 units

26.67 units · 0.27 mL · 2 mg from 15 mg + 2 mL

Math only. The amounts in these tables are reference values for the arithmetic, not dose recommendations.

Common questions

How much water goes in a 15 mg vial of Retatrutide?

That choice only changes the concentration. With 2 mL, a 15 mg vial is 7.5 mg/mL; with 1 mL it is 15 mg/mL. Less water means fewer units per dose and harder-to-read marks for small doses.

How many units is 1 mg from a 15 mg vial?

With 2 mL of water, 1 mg is 13.3 units on a U-100 syringe. With other water amounts, see the table.

How many doses are in a 15 mg vial?

Divide the vial size by the dose (in the same unit). The calculator on this page shows the number of whole doses for any dose you pick.

More on Retatrutide

DosageDoses used in published trials, the titration pattern and a units chart.CalculatorVial, water and dose to syringe units.Side effectsWhat labels and studies report, and what is unknown.ResultsStudy outcomes and when they were measured.PricePrice per mg and per week from dated listings. No vendor links.Legal statusFDA, compounding and WADA status with dates.

Sources

1Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial (Jastreboff AM et al.)New England Journal of Medicine · 2023PMID 37366315Accessed 2 Oct 2026
2Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity (TRIUMPH-1; Jastreboff AM et al.)New England Journal of Medicine · 2026PMID 42814954Accessed 2 Oct 2026
3A Phase 2 Study of Once-Weekly LY3437943 Compared With Placebo in Participants Who Have Obesity or Are Overweight With Weight-Related Comorbidities (NCT04881760; arms and posted results)ClinicalTrials.gov (U.S. National Library of Medicine) · 2021clinicaltrials.govAccessed 2 Oct 2026
4Metric (SI) Prefixes (NIST Reference on Constants, Units, and Uncertainty)National Institute of Standards and Technology (NIST) · 2025physics.nist.govAccessed 2 Oct 2026
5BASAGLAR (insulin glargine) injection, prescribing information (DailyMed)U.S. Food and Drug Administration / DailyMed (Eli Lilly and Company label) · 2026dailymed.nlm.nih.govAccessed 2 Oct 2026

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