How much bacteriostatic water to reconstitute 10mg retatrutide?

There is no official answer, because retatrutide has no approved label. As arithmetic only: 10 mg in 1 mL is 10 mg/mL (2 mg reads 20 units), in 2 mL is 5 mg/mL (2 mg reads 40 units), and in 3 mL is 3.333 mg/mL (2 mg reads 60 units). More water lowers the concentration and raises the unit reading for the same mg. Research vials sold online are unapproved products.

How do you reconstitute retatrutide?

This page does not give preparation or handling steps. Retatrutide is investigational, it is not approved by any regulator per Lilly's Aug 12, 2026 release, and FDA warning letters call research-labeled vials unapproved new drugs. What the chart covers is the concentration arithmetic: mg ÷ mL, then units on a U-100 scale.

What is the concentration of a 10 mg retatrutide vial with 2 mL of water?

10 mg ÷ 2 mL = 5 mg/mL. On a U-100 scale, 100 units equal 1 mL, so each unit corresponds to 0.05 mg and 10 units to 0.5 mg. A 200-unit total volume holds the full 10 mg.

How many units is 2 mg of retatrutide?

It depends on concentration: 20 units at 10 mg/mL, 40 units at 5 mg/mL, 60 units at 3.333 mg/mL and 80 units at 2.5 mg/mL. The formula is dose mg ÷ concentration mg/mL × 100. The units chart guide lists every Phase 3 step at these concentrations.

What is GLP-3 reconstitution?

GLP-3 is a street name for retatrutide, not a scientific term; an FDA warning letter dated Aug 24, 2026 cites a product sold as GLP-3R. The vial arithmetic is the same as for any other vial: concentration = mg ÷ mL and units = dose ÷ concentration × 100. Products sold under that name are unapproved.

Retatrutide Reconstitution Chart (Vial × Water → Units)

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Short answer

Concentration = vial mg ÷ water mL, and U-100 units = dose mg ÷ concentration × 100. Example: 10 mg in 2 mL of water is 5 mg/mL, so 2 mg reads 40 units, while 12 mg would need 240, beyond a 100-unit syringe. Arithmetic only; retatrutide is unapproved and trial-only, as of Oct 19, 2026.

On this page11 sections

Concentration by vial size and water volume
Units matrix: 5 to 60 mg vials
How water volume changes the reading
Rounding to the nearest 0.5 unit
The 2-unit readability floor
Syringe capacity: 30, 50 and 100 units
Dead space
Legal status: research vials are unapproved products
Related charts
FAQ
Sources

Key facts (as of Oct 19, 2026)
Item	Value	Source
Approval status	Not approved for human use by any regulator (Lilly, Aug 12, 2026)	Eli Lilly, Aug 12, 2026
FDA on research-use-only labeling	Retatrutide sold for research purposes only is an unapproved new drug (warning letter, Dec 10, 2024)	FDA, Dec 10, 2024
FDA on compounding	Compounded retatrutide does not qualify for the 503A or 503B exemptions	FDA, Sep 9, 2025
Street name in an FDA letter	Sold as GLP-3R and called an unapproved new drug (Aug 24, 2026)	FDA, Aug 24, 2026
Listings Lilly reported to platforms	More than 14,000, in over 100 countries	Eli Lilly, Aug 12, 2026
Phase 3 trial dose strengths	2, 4, 6, 9 and 12 mg once weekly	Eli Lilly, Dec 11, 2025
Planned U.S. submission	Biologics License Application planned for Q1 2027	Eli Lilly, Sep 29, 2026

Also useful: Retatrutide mg to units, Reconstitution (any vial).

From vial to syringe: a retatrutide worked example in three steps

Vial and water
10 mg + 2 mL
The mg in the vial never changes; water only sets how spread out it is.
Concentration
10 ÷ 2 = 5 mg/mL
Milligrams in every milliliter of solution.
Units on a U-100 syringe
2 mg ÷ 5 = 0.4 mL = 40 U
100 units = 1 mL, so units = mL × 100 (rounded to 0.5 U).

This chart is lab arithmetic for a research vial: how many milligrams per milliliter a given vial and water volume produce, and what a given mg amount reads on a U-100 scale. It is not a preparation guide. Retatrutide is investigational, it is not approved by any regulator (Eli Lilly, Aug 12, 2026), and it is legally available only to participants in Eli Lilly clinical trials. Background is on the retatrutide hub.

Concentration by vial size and water volume

Concentration (C) is the vial’s labeled mg divided by the mL of liquid it is dissolved in. On a U-100 scale, 100 units equal 1 mL, so one unit corresponds to C ÷ 100 mg.

Concentration (mg/mL) and mg per unit for common research vial sizes at 1, 2 and 3 mL (arithmetic)
Vial	1 mL	2 mL	3 mL	mg per unit at 2 mL
5 mg	5 mg/mL	2.5 mg/mL	1.667 mg/mL	0.025 mg
10 mg	10 mg/mL	5 mg/mL	3.333 mg/mL	0.05 mg
15 mg	15 mg/mL	7.5 mg/mL	5 mg/mL	0.075 mg
20 mg	20 mg/mL	10 mg/mL	6.667 mg/mL	0.1 mg
30 mg	30 mg/mL	15 mg/mL	10 mg/mL	0.15 mg
60 mg	60 mg/mL	30 mg/mL	20 mg/mL	0.3 mg

Total volume sets the total units: 1 mL is 100 units, 2 mL is 200 units and 3 mL is 300 units, whatever the vial size. The reconstitution calculator computes any vial and volume, and the general reconstitution tool works for other compounds.

Units matrix: 5 to 60 mg vials

Each table below takes one vial size and shows the U-100 reading for each mg amount at 1, 2 and 3 mL. The mg amounts include the Phase 3 trial dose strengths of 2, 4, 6, 9 and 12 mg (Eli Lilly, Dec 11, 2025). A dash means the reading would exceed 100 units or the amount exceeds the vial.

Retatrutide research vials: U-100 unit readings by vial mg, water mL and mg amount. Arithmetic for research and education only.

5 mg vial: U-100 units to draw for each dose (1 mL = 5 mg/mL; 2 mL = 2.5 mg/mL; 3 mL = 1.667 mg/mL)
Dose	1 mL water5 mg/mL	2 mL water2.5 mg/mL	3 mL water1.667 mg/mL
0.5 mg	10 U	20 U	30 U
1 mg	20 U	40 U	60 U
2 mg	40 U	80 U	—
4 mg	80 U	—	—
6 mg	—	—	—
9 mg	—	—	—
12 mg	—	—	—

10 mg vial: U-100 units to draw for each dose (1 mL = 10 mg/mL; 2 mL = 5 mg/mL; 3 mL = 3.333 mg/mL)
Dose	1 mL water10 mg/mL	2 mL water5 mg/mL	3 mL water3.333 mg/mL
0.5 mg	5 U	10 U	15 U
1 mg	10 U	20 U	30 U
2 mg	20 U	40 U	60 U
4 mg	40 U	80 U	—
6 mg	60 U	—	—
9 mg	90 U	—	—
12 mg	—	—	—

15 mg vial: U-100 units to draw for each dose (1 mL = 15 mg/mL; 2 mL = 7.5 mg/mL; 3 mL = 5 mg/mL)
Dose	1 mL water15 mg/mL	2 mL water7.5 mg/mL	3 mL water5 mg/mL
0.5 mg	3.5 U (raw 3.33)	6.5 U (raw 6.67)	10 U
1 mg	6.5 U (raw 6.67)	13.5 U (raw 13.33)	20 U
2 mg	13.5 U (raw 13.33)	26.5 U (raw 26.67)	40 U
4 mg	26.5 U (raw 26.67)	53.5 U (raw 53.33)	80 U
6 mg	40 U	80 U	—
9 mg	60 U	—	—
12 mg	80 U	—	—

20 mg vial: U-100 units to draw for each dose (1 mL = 20 mg/mL; 2 mL = 10 mg/mL; 3 mL = 6.667 mg/mL)
Dose	1 mL water20 mg/mL	2 mL water10 mg/mL	3 mL water6.667 mg/mL
0.5 mg	2.5 U	5 U	7.5 U
1 mg	5 U	10 U	15 U
2 mg	10 U	20 U	30 U
4 mg	20 U	40 U	60 U
6 mg	30 U	60 U	90 U
9 mg	45 U	90 U	—
12 mg	60 U	—	—

30 mg vial: U-100 units to draw for each dose (1 mL = 30 mg/mL; 2 mL = 15 mg/mL; 3 mL = 10 mg/mL)
Dose	1 mL water30 mg/mL	2 mL water15 mg/mL	3 mL water10 mg/mL
0.5 mg	1.5 U (raw 1.67)	3.5 U (raw 3.33)	5 U
1 mg	3.5 U (raw 3.33)	6.5 U (raw 6.67)	10 U
2 mg	6.5 U (raw 6.67)	13.5 U (raw 13.33)	20 U
4 mg	13.5 U (raw 13.33)	26.5 U (raw 26.67)	40 U
6 mg	20 U	40 U	60 U
9 mg	30 U	60 U	90 U
12 mg	40 U	80 U	—

60 mg vial: U-100 units to draw for each dose (1 mL = 60 mg/mL; 2 mL = 30 mg/mL; 3 mL = 20 mg/mL)
Dose	1 mL water60 mg/mL	2 mL water30 mg/mL	3 mL water20 mg/mL
0.5 mg	1 U (raw 0.83)	1.5 U (raw 1.67)	2.5 U
1 mg	1.5 U (raw 1.67)	3.5 U (raw 3.33)	5 U
2 mg	3.5 U (raw 3.33)	6.5 U (raw 6.67)	10 U
4 mg	6.5 U (raw 6.67)	13.5 U (raw 13.33)	20 U
6 mg	10 U	20 U	30 U
9 mg	15 U	30 U	45 U
12 mg	20 U	40 U	60 U

Units = dose mg ÷ (vial mg ÷ water mL) × 100, rounded to the nearest 0.5 U; the raw value is shown in brackets when rounding changed it. A dash means the draw would exceed a 100-unit syringe or the vial. Arithmetic only; not dosing advice.

How water volume changes the reading

Water does not change how many milligrams are in the vial. It changes how spread out they are. Doubling the volume halves the concentration, and that doubles the unit reading for the same mg. Take a 10 mg vial:

One 10 mg vial at three water volumes, unit readings for the Phase 3 dose strengths (arithmetic; dash = over 100 U)
mg amount	1 mL (10 mg/mL)	2 mL (5 mg/mL)	3 mL (3.333 mg/mL)
0.5 mg	5 U	10 U	15 U
2 mg	20 U	40 U	60 U
4 mg	40 U	80 U	— (120 U)
6 mg	60 U	— (120 U)	— (180 U)
9 mg	90 U	— (180 U)	— (270 U)
12 mg	— (120 U)	— (240 U)	— (360 U)

Two effects pull in opposite directions. Less water gives smaller readings, so larger mg amounts still fit under 100 units; more water gives larger readings, which are easier to read precisely for small amounts. The inverse formula shows the trade-off directly: water mL = vial mg × units ÷ (dose mg × 100). For a 10 mg vial, 2 mg reads 20 units at 1 mL and 60 units at 3 mL.

Rounding to the nearest 0.5 unit

U-100 scales are marked in 1-unit or 2-unit steps, so our tools round every reading to the nearest 0.5 unit, the finest step a person can reasonably read. Most combinations in the matrix land on whole numbers, but not all:

4 mg at 15 mg/mL (30 mg in 2 mL) is 26.67 units, shown as 26.5. That reading corresponds to 3.975 mg, 0.6% under 4 mg.
2 mg at 6.667 mg/mL (20 mg in 3 mL) is exactly 30 units, with no rounding error.
9 mg at 20 mg/mL (60 mg in 3 mL) is exactly 45 units.

The rounding error is tiny for readings above about 20 units and grows as the reading shrinks.

The 2-unit readability floor

Below 2 units, a half-unit rounding step is a large share of the reading. Our calculators flag any result under 2 units:

0.5 mg at 30 mg/mL (60 mg in 2 mL) is 1.67 units, shown as 1.5. That reading corresponds to 0.45 mg, 10% under.
0.5 mg at 60 mg/mL (60 mg in 1 mL) is 0.83 units, shown as 1. That corresponds to 0.6 mg, 20% over.

The same 0.5 mg reads 10 units at 5 mg/mL, where a half-unit step is 5% of the reading. High-concentration combinations are the ones where small amounts become hard to read.

Syringe capacity: 30, 50 and 100 units

U-100 syringes come in 30-unit (0.3 mL), 50-unit (0.5 mL) and 100-unit (1 mL) sizes. A reading above the capacity cannot be shown in one measurement. At 5 mg/mL, the 4 mg Phase 3 step reads 80 units, which fits only the 100-unit size. At 10 mg/mL, the 6 mg step reads 60 units, above both the 30-unit and 50-unit sizes. At 20 mg/mL, the 12 mg step reads 60 units, while at 5 mg/mL it would be 240 units, over any single U-100 syringe. The units calculator warns when a reading exceeds the selected capacity.

Dead space

Dead space is liquid that stays in the hub and needle after a measurement and never leaves the syringe. It does not change the concentration or the unit reading, but it does use up volume. The calculators take dead space as an optional input in units. As a hypothetical: a 10 mg vial in 2 mL holds 200 units of liquid. At 40 units per reading it yields 5 full readings with no dead space. If each measurement also lost 2 units, the arithmetic becomes 200 ÷ 42 = 4.76, so only 4 full readings. The value of 2 units here is an example input, not a measured figure for any product.

Legal status: research vials are unapproved products

Retatrutide vials sold online as “research peptides” are not trial drug and are not approved products. The FDA has said so in writing several times:

FDA warning letters that address retatrutide (fetched from fda.gov)
Date	What the letter says
Dec 10, 2024	Retatrutide labeled for research purposes only is still an unapproved new drug
Sep 9, 2025	Compounded retatrutide does not qualify for the 503A or 503B compounding exemptions
Mar 31, 2026	Retatrutide sold as “GLP-1-R peptide” is an unapproved new drug
Aug 24, 2026	Retatrutide sold as “GLP-3R” is an unapproved new drug

Sources: (FDA, Dec 10, 2024) (FDA, Sep 9, 2025) (FDA, Mar 31, 2026) (FDA, Aug 24, 2026). On Aug 12, 2026, Lilly said no retatrutide medicine had been approved by any regulator, announced six new U.S. lawsuits against sellers, and said it had reported more than 14,000 websites, ads, posts and listings in over 100 countries (Eli Lilly, Aug 12, 2026). Lilly plans to submit a U.S. Biologics License Application in Q1 2027 (Eli Lilly, Sep 29, 2026). The labeled mg on an unapproved vial is a seller’s claim; no regulator has checked it, so arithmetic built on it inherits that uncertainty.

The units chart lists mg-to-units readings at fixed concentrations. The dosage chart shows the trial ladders behind the 2, 4, 6, 9 and 12 mg strengths, which Lilly reported as escalating from 2 mg every 4 weeks (Eli Lilly, May 21, 2026).

Frequently asked questions

How much bacteriostatic water to reconstitute 10mg retatrutide?: There is no official answer, because retatrutide has no approved label. As arithmetic only: 10 mg in 1 mL is 10 mg/mL (2 mg reads 20 units), in 2 mL is 5 mg/mL (2 mg reads 40 units), and in 3 mL is 3.333 mg/mL (2 mg reads 60 units). More water lowers the concentration and raises the unit reading for the same mg. Research vials sold online are unapproved products.
How do you reconstitute retatrutide?: This page does not give preparation or handling steps. Retatrutide is investigational, it is not approved by any regulator per Lilly's Aug 12, 2026 release, and FDA warning letters call research-labeled vials unapproved new drugs. What the chart covers is the concentration arithmetic: mg ÷ mL, then units on a U-100 scale.
What is the concentration of a 10 mg retatrutide vial with 2 mL of water?: 10 mg ÷ 2 mL = 5 mg/mL. On a U-100 scale, 100 units equal 1 mL, so each unit corresponds to 0.05 mg and 10 units to 0.5 mg. A 200-unit total volume holds the full 10 mg.
How many units is 2 mg of retatrutide?: It depends on concentration: 20 units at 10 mg/mL, 40 units at 5 mg/mL, 60 units at 3.333 mg/mL and 80 units at 2.5 mg/mL. The formula is dose mg ÷ concentration mg/mL × 100. The units chart guide lists every Phase 3 step at these concentrations.
What is GLP-3 reconstitution?: GLP-3 is a street name for retatrutide, not a scientific term; an FDA warning letter dated Aug 24, 2026 cites a product sold as GLP-3R. The vial arithmetic is the same as for any other vial: concentration = mg ÷ mL and units = dose ÷ concentration × 100. Products sold under that name are unapproved.

Sources

Lilly calls on online platforms, payment companies and regulators to shut down the illegal retatrutide black market. Eli Lilly and Company (via PR Newswire), Aug 12, 2026. Accessed Oct 19, 2026.
Lilly's triple agonist, retatrutide, delivered substantial weight loss and A1C reduction, underscoring its potential promise for people with obesity and type 2 diabetes. Eli Lilly and Company (via PR Newswire; also investor.lilly.com), Sep 29, 2026. Accessed Oct 19, 2026.
Lilly's triple agonist, retatrutide, delivered weight loss of up to an average of 71.2 lbs along with substantial relief from osteoarthritis pain in first successful Phase 3 trial. Eli Lilly and Company (via PR Newswire), Dec 11, 2025. Accessed Oct 19, 2026.
Warning Letter: Prime Vitality, Inc. dba Prime Peptides, MARCS-CMS 695156. U.S. Food and Drug Administration (CDER), Dec 10, 2024. Accessed Oct 19, 2026.
Warning Letter: ASN-LABS, MARCS-CMS 716459. U.S. Food and Drug Administration, Sep 9, 2025. Accessed Oct 19, 2026.
Warning Letter: Gram Peptides, MARCS-CMS 721806. U.S. Food and Drug Administration, Mar 31, 2026. Accessed Oct 19, 2026.
Warning Letter: Peak Performance Peptides, MARCS-CMS 735127. U.S. Food and Drug Administration, Aug 24, 2026. Accessed Oct 19, 2026.
Lilly's triple agonist, retatrutide, delivered powerful weight loss in pivotal Phase 3 obesity trial. Eli Lilly and Company (via PR Newswire; also investor.lilly.com), May 21, 2026. Accessed Oct 19, 2026.