How much bacteriostatic water do I add to a retatrutide vial?

Use the volume in your product's instructions or from your prescriber or pharmacist. The water doesn't change how much retatrutide is in the vial, only the concentration: a 10 mg vial with 2 mL is 5 mg/mL, and adding more water makes each unit on the syringe hold less.

How do I convert retatrutide from mg to syringe units?

Divide the amount in mg by the concentration in mg/mL to get mL, then multiply by 100 for a U-100 insulin syringe (50 for U-50, 40 for U-40). The calculator on this page does it when you enter the amount from your prescriber or label.

How should I store retatrutide after mixing?

Follow the vial label. Research products don't come with FDA-reviewed stability data, so keep the vial away from heat and light, write the mixing date on it, and don't use it if the solution turns cloudy or has particles.

Retatrutide reconstitution calculator

Concentration and syringe-unit math for retatrutide vials (5, 10, 20 and 30 mg), with the calculator set up for a 10 mg vial and 2 mL of diluent. Change both to match your own vial.

Investigational, not FDA-approvedGLP-1 and incretin compounds

Retatrutide is an investigational agonist of three hormone receptors (GIP, GLP-1 and glucagon) being studied by Eli Lilly in clinical trials.

Investigational, not FDA-approved. Retatrutide has no current FDA-approved label, so there is no official dose and this page doesn't list one. Products sold for “research use only” are not reviewed by the FDA for identity, purity or sterility. This page is arithmetic only. If you have a lab report, our COA guide shows how to check it.

Reconstitution calculator

Enter the numbers from your own vial, and pick the syringe in your hand. Check the U- number and size printed on the syringe box.

Concentration

5 mg/mL

5,000 mcg/mL

Draw volume

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Syringe units

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U-100 1 mL, holds 100

Draws in the vial

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1Concentration: 10 mg ÷ 2 mL = 5 mg/mL
2Draw volume: amount in mg ÷ 5 mg/mL = draw mL
3Syringe units: draw mL × 100 units per mL (U-100) = units

Math only, not dosing advice. Follow your prescriber or label. Real vials give slightly less than the full-draw count: a little liquid stays in the vial and needle. Your last setup is saved in this browser only; Clear removes it.

Save your vial in Caliper and it remembers the concentration and use-by date you entered, alongside your dose log. The calculator above is a browser tool and is not part of the app.

Save my vial in Caliper

The calculator starts with a 10 mg vial and 2 mL of diluent as an example setup, not a recommendation. Enter the vial size on your label and the volume you actually added. The amount field starts empty: Caliper never suggests an amount.

Retatrutide concentration by vial size

Vial mg ÷ mL of diluent = mg per mL. Plain arithmetic for retatrutide label sizes; the volumes are examples, not recommendations.

Retatrutide: mg/mL by vial size and diluent volume
Vial	1 mL	2 mL	3 mL
5 mg	5 mg/mL	2.5 mg/mL	1.667 mg/mL
10 mg	10 mg/mL	5 mg/mL	3.333 mg/mL
20 mg	20 mg/mL	10 mg/mL	6.667 mg/mL
30 mg	30 mg/mL	15 mg/mL	10 mg/mL

Syringe units to mg at 5 mg/mL

What a given number of U-100 units holds when a 10 mg vial has 2 mL added. This is a unit conversion, like a map scale, not a dose. A different vial size or volume changes every row, so use the calculator for your own numbers.

10 mg vial + 2 mL (5 mg/mL): conversion only
U-100 units	mL	mg	mcg
5 units	0.05	0.25	250
10 units	0.1	0.5	500
20 units	0.2	1	1,000
25 units	0.25	1.25	1,250
50 units	0.5	2.5	2,500

Mixing and storing retatrutide

Retatrutide vials are sold in several sizes, and the size changes every number: a 10 mg vial with 2 mL is 5 mg/mL, while a 20 mg vial with 2 mL is 10 mg/mL, so the same number of units holds twice as much. Check the vial size on the label (and the lab report, if you have one) before entering it.

Add the diluent slowly down the inside wall of the vial and let the powder dissolve; swirling gently is gentler on the peptide than shaking. Use the volume your instructions give, and enter that same volume in the calculator.

Research vials don't come with FDA-reviewed storage or stability data. Follow the storage line on the vial label, keep the vial away from heat and light, and write the date on it when you mix it. Our storage guide covers fridge temperatures, use-by dates and travel.

Status: Not FDA-approved for any use. The FDA states that retatrutide is not a component of any FDA-approved drug, has not been found safe and effective for any condition, and cannot be used in compounding under federal law. There is no official label, so this page has no dosing information.

More detail: how to reconstitute peptides and how to store peptides and GLP-1s. To convert units you've already drawn, use the units-to-mg converter.

FAQ

How much bacteriostatic water do I add to a retatrutide vial?: Use the volume in your product's instructions or from your prescriber or pharmacist. The water doesn't change how much retatrutide is in the vial, only the concentration: a 10 mg vial with 2 mL is 5 mg/mL, and adding more water makes each unit on the syringe hold less.
How do I convert retatrutide from mg to syringe units?: Divide the amount in mg by the concentration in mg/mL to get mL, then multiply by 100 for a U-100 insulin syringe (50 for U-50, 40 for U-40). The calculator on this page does it when you enter the amount from your prescriber or label.
Does this page give a retatrutide dose?: No. Retatrutide has no current FDA-approved label, so there is no official dose, and this page doesn't list one. The calculator only converts the numbers you enter.
Is retatrutide FDA-approved?: Not FDA-approved for any use. The FDA states that retatrutide is not a component of any FDA-approved drug, has not been found safe and effective for any condition, and cannot be used in compounding under federal law. There is no official label, so this page has no dosing information.
How should I store retatrutide after mixing?: Follow the vial label. Research products don't come with FDA-reviewed stability data, so keep the vial away from heat and light, write the mixing date on it, and don't use it if the solution turns cloudy or has particles.

Related compounds

Calculators by vial size

The same arithmetic for any compound, with a 1, 2 and 3 mL concentration table.

Related guides

Sources

Updated October 17, 2026

For adults 18+. Educational math only, not medical advice. This page does not recommend any dose, dilution, syringe or compound, and doesn't say where to get one. Always follow your prescriber's instructions and the product label, and ask a pharmacist if a number doesn't look right.