Retatrutide 10mg Dosage Chart: Units and Weeks Per Vial

Retatrutide 10mg Dosage Chart: Units to Draw at 1, 2 and 3mL

Find the water you added on the left and your dose across the top. Each cell is the mark to draw to on a U-100 insulin syringe, with the volume in mL underneath.

The full grid as an image. Amber cells with a dagger are over 100 units; grey cells are doses larger than the vial holds. Download the chart (PNG).

† Over 100 units, so more than 1mL, which is more than one standard 1mL U-100 syringe holds in a single draw. n/a: 12mg is more than the 10mg in the vial. All values assume the vial holds exactly 10mg.

The unit marks come from the U-100 standard. U-100 means 100 units per mL (the strength printed on Lilly's Humulin N label). So 100 units is a full 1mL syringe, and the largest dose one 100-unit draw can hold from this vial is 10mg at 1mL, 5mg at 2mL and 3.33mg at 3mL.

Other vial sizes: the 20mg vial dosage chart and the 30mg vial dosage chart. For any other vial and water combination, the dose-to-units calculator does the conversion.

How to Read the Grid

Pick the row for the water you mixed in, then the dose column. Worked example: 4mg from a vial mixed with 2mL. The concentration is 10 / 2 = 5mg per mL, so 4mg is 4 / 5 = 0.8mL, which is 80 units. The shortcut gives the same answer: 4 x 2 x 10 = 80.

What Each Water Volume Does to the Draw

The water volume changes the size of each draw, never the amount of retatrutide in the vial. At 1mL the marks are smallest: every dose up to 10mg stays at or under 100 units, but 1mg is only 10 units. 2mL sits in the middle: 2mg is 40 units and 4mg is 80, while 8mg and 9mg run past 100. 3mL gives the largest marks at low doses (2mg is 60 units), but 4mg already reaches 120 units.

The mixing itself is covered in the step-by-step reconstitution guide, and the full reconstitution chart lists other vial sizes side by side.

Is There a 10mg Retatrutide Dose?

Not in the trials that define retatrutide dosing. The Phase 2 obesity trial (Jastreboff et al., NEJM 2023) assigned participants to 1, 4, 8 or 12mg once weekly. Its registry record lists two starting groups each for the 4mg and 8mg arms, while the 12mg arm started at 2mg (ClinicalTrials.gov NCT04881760). The Phase 3 TRIUMPH-1 trial assigned 2,339 adults with obesity and without diabetes to 4, 9 or 12mg weekly, or placebo, for 80 weeks (NEJM, published online September 2026). The published TRIUMPH-1 design starts every retatrutide arm at 2mg and steps up every four weeks along a 2, 4, 6, 9, 12mg ladder, stopping at the assigned dose (Giblin et al., Diabetes Obes Metab 2026). Neither trial had a 10mg arm, and neither ladder has a 10mg step.

So a search for a 10mg dosage almost always means the vial. Research vials are labeled by total content, and 10mg is one of several sizes sold. In the grid, the 1mg column matches the Phase 2 1mg arm and the 9mg column is a TRIUMPH-1 dose. Doses below 2mg are covered in microdosing retatrutide.

Retatrutide has no FDA approval. FDA states that it cannot be used in compounding under federal law, and FDA has warned companies selling retatrutide products falsely labeled as for research purposes, calling such products of unknown quality and possibly harmful. That matters here. Every table on this page assumes exactly 10mg in the vial, and for a product FDA describes as of unknown quality, that is an assumption, not a known fact.

How Many Doses and Weeks Does a 10mg Vial Hold?

Two limits decide how long a vial lasts: the 10mg inside it, and how long a multi-dose vial should stay in use after the first puncture. The table counts weekly doses under both, assuming the vial holds exactly 10mg and nothing is lost in the vial or syringe.

* Weekly draws on days 0, 7, 14 and 21, counted from the first puncture. FDA's wording (within 28 days after first use) does not say whether a draw on day 28 itself counts. This page treats day 28 as the discard day. If a day-28 draw counts, five weekly draws fit, which changes only the 1mg row (5 draws, 5mg unused) and the 2mg row (5 draws, 0mg unused). Doses by weight = 10mg divided by the dose, rounded down.

Dark bars count doses by weight; light bars count weekly draws on days 0, 7, 14 and 21. The two match from 4mg upward and differ at 2mg and 1mg.

Where the 28 days comes from. On its page about unapproved GLP-1 drugs, FDA notes that compounded GLP-1 medications may be dispensed in multi-dose vials. It generally recommends that multi-dose vials of sterile medications be used within 28 days of first use because contamination risk rises after that, and it tells consumers to discard such a vial within 28 days even if medication remains. Retatrutide has no FDA label, so there is no approved in-use period for a mixed retatrutide vial. This page uses FDA's 28 days as a planning boundary, not as retatrutide stability data, and counts day 28 as the discard day.

At 2mg or Less: Where the 28-Day Window Comes In

By weight, a 10mg vial holds five 2mg doses or ten 1mg doses. With day 28 as the discard day, four weekly draws fit, so at 2mg the fifth dose would fall on the discard day and 2mg is left. If a day-28 draw counts, all five 2mg doses fit and the vial and the window run out together. At 1mg the window limits either way: 6mg is left after four draws, 5mg after five.

At 4mg and Above: The Vial Runs Out First

At 4mg the vial supplies two doses and leaves 2mg, not enough for a third. At 8mg it supplies one dose with 2mg left, and at 9mg one dose with 1mg left. The last full dose comes out by day 7, long before day 28, so the window never comes into play. Below 2mg, time is the limit; from 4mg up, the 10mg is. 2mg is the borderline case, and how day 28 is counted decides it.

What a 10mg Vial Cannot Do

Supply a 12mg dose. 12mg is 1.2 times the vial's entire content, so a single 10mg vial cannot provide even one dose at the top Phase 2 and TRIUMPH-1 level. A 9mg dose fits once, with 1mg left.

Fit the larger doses into one standard syringe at 2 or 3mL. At 2mL, 8mg is 160 units; at 3mL, 4mg is already 120 units. Each is more than the 100 units a 1mL U-100 syringe holds, which is why those cells carry a dagger in the grid.

The Phase 2 Ladder Against 10mg Vials

The Phase 2 12mg arm stepped through 2, 4, 8 and 12mg, four weeks at each level (the trial protocol specifies 4-week increments). The trial counts the first injection as Week 0, so the protocol puts the first 12mg dose at Week 12; this page counts the first injection as week 1, so the same dose appears below as week 13. Suppose 10mg vials are the only size on hand and each dose comes from a single vial. A new vial is opened only when the current one can't supply the next dose, because too little is left or it has reached the 28-day mark. The arithmetic looks like this:

By weight alone, 56mg is 5.6 vials, so six would do if leftovers could be combined. Because no dose here draws from two vials, 2mg stays behind in every vial (once at 2mg, twice at 4mg, four times at 8mg), which pushes the count to seven. The 28-day window changes neither count: in this sequence no vial is drawn from more than 21 days after its first puncture, and with combined leftovers six vials still suffice. This shows the limits of the vial size, not a plan to follow.

Reverse Lookup: How Many mg Did the Syringe Draw?

Read the syringe mark on the left and the water volume across the top. For a 10mg vial the formula is mg = units / (10 x mL of water).

The same mark means a different dose at each water volume. Take 40 units: that is 4mg from a vial mixed with 1mL, 2mg with 2mL and 1.33mg with 3mL. Misremember how much water went in, and a planned 2mg draw at 40 units turns into 4mg or 1.33mg. Every reading on this page depends on that one number, so it is worth noting the day you mix.

Video: Retatrutide Trial Doses Explained

Dr. Alex Tatem, a physician, walks through the doses used in retatrutide trials and why the amount in a research vial is uncertain (18:26).

Investigational Drug Notice

References

1. Jastreboff AM, Kaplan LM, Frías JP, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial. N Engl J Med. 2023;389(6):514-526. DOI: 10.1056/NEJMoa2301972. PMID 37366315. (Phase 2 dose arms and the 2, 4, 8, 12mg escalation.)
2. ClinicalTrials.gov. A Study of LY3437943 in Participants Who Have Obesity or Are Overweight (NCT04881760). clinicaltrials.gov/study/NCT04881760. (Registered arms, including the two starting groups for the 4mg and 8mg arms.) Study Protocol J1I-MC-GZBF(b), section 4.1.1.1, posted on the same record: Prot_000.pdf. (Doses increased at 4-week increments until the maintenance dose was reached.)
3. Jastreboff AM, Kaplan LM, Davies MJ, et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity. N Engl J Med. Published online September 29, 2026. DOI: 10.1056/NEJMoa2604169. PMID 42814954. (TRIUMPH-1: 4, 9 and 12mg weekly versus placebo for 80 weeks.)
4. ClinicalTrials.gov. TRIUMPH-1 (NCT05929066). clinicaltrials.gov/study/NCT05929066. (Phase 3 registry record.)
5. Giblin K, Kaplan LM, Somers VK, et al. Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials. Diabetes Obes Metab. 2026;28(1):83-93. DOI: 10.1111/dom.70209. PMID 41090431. PMCID PMC12673447. (Figure 2A: TRIUMPH-1 escalation from 2mg in 4-week steps through 4, 6 and 9mg to the assigned dose.)
6. U.S. Food and Drug Administration. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss. Content current as of 10/01/2026. fda.gov. (28-day recommendation for multi-dose vials; retatrutide and compounding; products falsely labeled for research purposes.)
7. Eli Lilly and Company. HUMULIN N (insulin isophane human) injectable suspension, Prescribing Information, section 3. DailyMed set ID f6edd793-440b-40c2-96b5-c16133b7a921, effective December 2025. dailymed.nlm.nih.gov. (Cited only for the U-100 definition: 100 units per mL.)

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