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Comparison

Semaglutide vs Retatrutide

An established weekly GLP-1 next to a newer triple-agonist studied for larger weight-loss numbers in early trials.

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Field
Semaglutide
Retatrutide
Category
GLP-1
GLP-1
Common alias
GLP-1 agonist (Ozempic, Wegovy)
Triple agonist (research)
Example vial
5 mg + 2 mL BAC water
10 mg + 2 mL BAC water
Concentration
2.50 mg/mL
5.00 mg/mL
Example dose
0.25 mg
2 mg
Doses per week
1× / week
1× / week
Doses per vial (rounded down)
20
5
Approx vial duration
20.0 weeks
5.0 weeks

Semaglutide and Retatrutide both show up in the same conversations, but they aren't interchangeable. The table above lays the vial math side by side so you can see how concentration, doses-per-vial, and weekly cadence actually compare. The sections below walk through what each one is, how each is studied, and how each shows up in a tracked log — in plain English, no recommendations.

Tiebreakers

Where Semaglutide and Retatrutide actually diverge

SemaglutideRetatrutide
Cadence1/wk1/wk
Concentration on example2.50 mg/mL5.00 mg/mL
Math weeks per vial20.05.0
CategoryGLP-1GLP-1

Bolded values are the higher of the two on numeric rows. Same-value rows aren't a verdict — they're shared properties.

Semaglutide vs Retatrutide: the actual decision

Retatrutide is the new player here, and the framing this page is built around is maturity. Semaglutide has years of large-population real-world data behind it; retatrutide is in late-phase trials with a phase-2 readout that reported about 24 percent average weight loss at 48 weeks in the highest-dose arm — a number larger than anything semaglutide has produced. The trade is what you would expect from a not-yet-approved molecule: less long-term safety data, fewer published edge cases, and prescribing pathways that still depend on which clinic and which compounding pharmacy a reader is working with.

Mechanism is the structural difference. Semaglutide hits GLP-1 alone; retatrutide is a triple agonist covering GLP-1, GIP, and glucagon. The glucagon arm is the unusual one — adding glucagon agonism on top of GLP-1 and GIP is the bet that pushed the trial weight-loss numbers higher, and it is also the source of the most frequently asked question about the molecule in real-world logs (whether the glucagon arm changes liver-fat dynamics in either direction). That question is still being answered in the published literature.

Mechanism, cadence, and what shows up in a log

Dosing cadence is identical at one subcutaneous shot per week, but every other variable in the schedule diverges. Semaglutide's 0.25 mg opening step exists to buy gut tolerance and produces almost no weight-loss signal in the first month. Retatrutide's published trial schedule begins at 2 mg and steps through 4, 8, and 12 mg arms, which means a reader logging the triple-agonist will see meaningful changes in unit count on a U-100 syringe at every titration event rather than a long flat opening. The mg-to-units converter linked below handles either molecule once vial concentration is set, but the unit ranges are not interchangeable across the two ladders.

For someone deciding which of the two to log over a six-month window, the practical question is mostly access and risk tolerance for a still-trial-stage molecule. Semaglutide's data set is mature; retatrutide's is promising but limited. The numbers in the side-by-side table are computed from the same example vial fields as every other comparison on the site, so the dose-per-vial and approximate vial-duration columns are directly comparable.

Semaglutide vs Retatrutide: the numbers, side by side

Start with what actually goes into a syringe. The example Semaglutide vial on this site reconstitutes 5 mg in 2 mL of bacteriostatic water — about 2.50 mg per mL, which yields roughly 20 doses at the 0.25 mg example and lasts about 20.0 weeks at 1 dose per week. The example Retatrutide vial reconstitutes 10 mg in 2 mL (5.00 mg/mL), which yields about 5 doses at 2 mg and stretches roughly 5.0 weeks at 1 dose per week. Those numbers are the starting point most people forget to write down, and they decide everything downstream — refill timing, unit count on the syringe barrel, and whether a 30-mL bac-water bottle stretches across one vial or two.

Category context matters too. Both Semaglutide and Retatrutide sit in the GLP-1 bucket, so the head-to-head questions readers bring here are usually about cadence, titration step size, and which of the two molecules logs more cleanly inside a longer protocol rather than a from-scratch category choice. Cadence helps frame the rest: Semaglutide is logged about 1× per week in the example schedule, Retatrutide about 1×.

The single most-asked-about mistake on each page is worth surfacing here, because they rarely overlap. On the Semaglutide side: Switching to a new vial of the same peptide and reusing the old unit count without re-running the calculation against the new vial's diluent volume. On the Retatrutide side: Reusing a unit count from a previous vial without re-checking the new vial's diluent volume. Both are the kind of thing a tracked log catches early and an untracked routine catches late.

Top Semaglutide question
How is semaglutide reconstituted?

By adding a measured volume of bacteriostatic water to the lyophilized vial through the rubber stopper, then swirling — not shaking — until the powder fully dissolves into a clear solution. The exact diluent volume is up to the user; common choices for a 5 mg vial are 1, 2, or 3 mL.

Top Retatrutide question
How is retatrutide reconstituted?

By drawing a measured volume of bacteriostatic water into a syringe and injecting it slowly into the lyophilized vial through the rubber stopper, then swirling — not shaking — until the powder fully dissolves into a clear solution.

The calculator pages linked below let you swap your own vial size, diluent volume, and dose into the same math — these example numbers exist so the comparison renders with concrete figures instead of placeholders.

Frequently asked questions about Semaglutide vs Retatrutide

How is semaglutide reconstituted?
By adding a measured volume of bacteriostatic water to the lyophilized vial through the rubber stopper, then swirling — not shaking — until the powder fully dissolves into a clear solution. The exact diluent volume is up to the user; common choices for a 5 mg vial are 1, 2, or 3 mL.
How many units of semaglutide are in 0.25 mg?
It depends on the concentration of your vial. On a 5 mg vial reconstituted with 2 mL of bacteriostatic water, 0.25 mg is exactly 10 units on a U-100 insulin syringe. On a 5 mg vial reconstituted with 1 mL, the same dose is 5 units.
Why is semaglutide dosed weekly?
Because its half-life is approximately one week, which keeps blood plasma levels stable on a once-weekly injection schedule. That cadence is part of why semaglutide became attractive relative to earlier GLP-1 peptides that required daily dosing.
How is retatrutide reconstituted?
By drawing a measured volume of bacteriostatic water into a syringe and injecting it slowly into the lyophilized vial through the rubber stopper, then swirling — not shaking — until the powder fully dissolves into a clear solution.
How many units of retatrutide are in 2 mg?
It depends on the concentration of your vial. On a 10 mg vial reconstituted with 2 mL of bacteriostatic water (5 mg per mL), 2 mg is exactly 40 units on a U-100 syringe.
Is retatrutide approved as a pharmaceutical?
Not at the time of writing. Retatrutide is investigational and is currently being studied in pharmaceutical clinical trials. Anything beyond that — including dosing decisions — is a conversation for a licensed healthcare professional, not for a calculator page.

Related on Peptide Pilot

Log Semaglutide and Retatrutide side by side in the app

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