Use this hub when you want the GLP-1 pages only: semaglutide, tirzepatide, retatrutide, the main head-to-head comparisons, and the utility tools people usually need right after the dose math.
Want the broader site first? Start with the calculator homepage. If you already know you are staying inside the GLP-1 side of the site, this page gets you there faster.
Start here when you need dose math, mixing guidance, and the core page for a specific compound.
Semaglutide dose math, reconstitution guidance, titration basics, and common client-facing reference questions.
Tirzepatide dose math, reconstitution help, weekly protocol basics, and quick reference guidance.
Retatrutide dosing math, storage notes, and the main page for this newer triple-agonist compound.
Use these when you want the side-by-side view before deciding which calculator or protocol page to open next.
The main comparison for weekly dosing, mechanism, weight-loss data, and common decision points.
See how the triple-agonist setup compares against the established single-agonist standard.
Compare the newer triple-agonist option against the more established dual-agonist approach.
After the calculator, people usually need one quick utility page to confirm units, storage, or timing.
Translate insulin syringe units into milliliters without reworking the math every time.
Check dosing cadence and timing at a glance when you want the quick reference version.
Review fridge, handling, and mixed-vial storage basics once the peptide is reconstituted.
The peptides on this hub share a mechanism family that separates them from everything else on the site. They are incretin mimetics, meaning they imitate gut hormones the body releases after eating, and they all act on the GLP-1 receptor as at least one of their targets.
What distinguishes them from each other is how many receptor pathways each one touches. Semaglutide is a single agonist acting on GLP-1 alone. Tirzepatide is a dual agonist adding GIP. Retatrutide is a triple agonist adding glucagon on top of both, and unlike the other two it is investigational rather than approved.
That progression matters for how you read the comparison pages. More receptor targets has correlated with larger average weight reduction in trials, but it also means less accumulated safety data for each newer compound, and effects that the earlier ones do not have.
This is the single most common misreading across these pages, so it is worth stating plainly on the hub. Semaglutide tops out at 2.4 mg weekly, tirzepatide at 15 mg weekly, and retatrutide has been studied to 12 mg weekly.
Those numbers do not mean tirzepatide is roughly six times stronger than semaglutide. They are different molecules with different receptor affinities and different potency per milligram. A milligram of one is not equivalent to a milligram of another, and comparing the ceilings tells you nothing useful about relative effect. The meaningful comparison is trial outcomes, which is what the head-to-head pages cover.
The same point applies to switching. There is no conversion factor between these compounds, and standard practice when moving between them is to restart the escalation schedule rather than attempt to match a previous dose.
All three use a multi-month titration schedule, and the reason is consistent across the class. Gastrointestinal side effects, mainly nausea, are most pronounced in the weeks right after a dose increase and ease as the body adapts.
The starting dose of each is therefore not intended to be therapeutic. It is a tolerance-building dose. Escalating faster than the labeled schedule trades a few weeks of time for considerably worse nausea, and is one of the more common reasons people abandon treatment before reaching an effective dose.
There is a pharmacokinetic reason too. With half-lives of roughly 5 to 7 days, these compounds take about four to five half-lives to reach steady levels, which is over a month. Escalating before levels have stabilized means stacking a higher dose on top of a concentration that is still climbing. The half-life chart covers that math in more detail.
Two conversions come up constantly with this group specifically. GLP-1 doses are usually written in micrograms while vials are labeled in milligrams, so the mcg to mg converter handles that mismatch. And because doses are small, the draw often lands in the low tens of units, where the syringe units converter and syringe size choice affect precision more than they would for a larger dose.