StackSensePeptide Half-Life and Timing: A Tracking Cheat Sheet
The most common question in this whole space isn't whether a compound is doing anything. It's timing: is it too early for the next dose, or too late for this one to still matter. Here's what half-life means for tracking, not dosing, and a cheat sheet across the compounds people actually stack.
Why timing questions outnumber every other question
Spend a week in any stacking community and the pattern is obvious. Fewer people are asking "does this work" than are asking "did I wait long enough" or "am I wasting the dose I already took." That question only has an answer if you know two things: roughly how long the compound stays active, and exactly when you last logged one. Most people have neither, because a spreadsheet records the day, not the hour, and nobody remembers half-life numbers off the top of their head.
What half-life means, and what it doesn't
Half-life is the time it takes for a logged amount to fall by roughly half, based on published pharmacokinetic references. After one half-life, about half is estimated to remain. After two, about a quarter. After five, under five percent. That's a curve, not a cliff, and it's a modeled estimate, not a blood test.
Two things follow from that. First, a short half-life (minutes to a few hours) means the compound clears fast, so timing within the day matters more than which day of the week it is. Second, a long half-life (multiple days) means doses overlap, which is exactly why weekly compounds build up over several weeks before leveling off, a pattern researchers call steady state.
The cheat sheet
Research-default half-life references for compounds that come up constantly in stacking logs. These are reference values from published research and community-reported estimates, not lab-verified numbers for any individual, and they are not dosing instructions.
| Compound | Category | Research half-life | What it means for tracking |
|---|---|---|---|
| Retatrutide | GLP-1 / GIP / glucagon | ~6 days (144h) | Long and slow-building; weekly logs are enough, but expect ~4-5 weeks before levels look steady |
| Semaglutide | GLP-1 | ~165h (~1 week) | Similar shape to retatrutide; included here for comparison since it's the most familiar reference point |
| BPC-157 | Repair | ~3-6 hours | Short; exact time and site matter more than which day you're on |
| TB-500 (Thymosin Beta-4) | Repair | ~24h (community estimate) | Longer than BPC-157 and systemic, so entries look sparser on the same timeline |
| GHK-Cu | Copper peptide | ~30-60 min (plasma) | Clears fast in plasma, but the visible effect is a slow signal, judge over weeks of photos and notes, not days |
| CJC-1295 (no-DAC / Mod GRF 1-29) | GH-axis | ~30 min | Short pulse, usually timed around sleep or a fasted window, easy to confuse with the DAC version if not logged separately |
| CJC-1295 (with DAC) | GH-axis | ~6-8 days | Binds to albumin and lingers; infrequent dosing, a completely different rhythm than no-DAC |
| Ipamorelin | GH-axis | ~2-3 hours | Short; usually logged alongside CJC-1295 in the same session |
| Tesamorelin | GH-axis | ~26-38 min (plasma) | Plasma clearance is fast, but the GH pulse it triggers plays out over hours, which is why timing relative to food matters more than the raw number |
Where these come from: retatrutide's ~6-day half-life is from the Phase 2 obesity trial published in the New England Journal of Medicine. Semaglutide's ~165-hour figure is from the DailyMed prescribing label. The rest are research defaults and community-reported estimates gathered from published peptide references, not clinical trial data, and individual results vary. None of this is a dosing instruction.
How to actually use this when you track
A number on a chart like this one is only useful next to your own log. Three habits make the difference:
- Log the time, not just the date. For anything with a half-life under a few hours, "Tuesday" tells you almost nothing. "Tuesday, 9:40pm, fasted" tells you whether the timing was even close to consistent.
- Match your read on "is it working" to the right half-life. A short-half-life compound shows its pattern within days. A multi-day compound needs weeks before a plateau or a trend means anything. Judging a 6-day compound after 3 days is judging noise.
- Don't confuse plasma half-life with felt effect. GHK-Cu and tesamorelin both clear from plasma in under an hour, but what they trigger (tissue response, a GH pulse) plays out on a much slower clock. Track the slow signal, not the fast one.
This is exactly what a decay-curve view is for: plotting your actual logged doses against a compound's reference half-life so you can see overlap and spacing at a glance, instead of doing the math by hand every time someone asks "is it too early for the next one."
Keep it next to the rest of your stack
Almost nobody runs one compound in isolation. A retatrutide protocol sits next to a repair peptide, a copper peptide serum, or a GH-axis stack, each on its own clock. If you're tracking retatrutide timing in one app and a BPC-157 and TB-500 stack in a notebook, you can't see whether a rough week traces back to the GLP-1, the repair peptides, or neither. One timeline is the only way to actually answer that.
Where StackSense fits
Disclosure: we build StackSense, so weigh this accordingly. Dedicated GLP-1 trackers do half-life math for that one drug class well, with real formulas and decay curves. What they don't do is cover the rest of a real stack: repair peptides, copper peptides, GH-axis compounds, and supplements, all in the same view.
StackSense holds 420+ compounds across peptides and supplements with half-life and decay context built in, next to your symptoms and bloodwork, with a baseline so you're reading a trend instead of a guess. It runs as a web app, so it's on your phone or desktop without an app store. It's a tracking tool, not a medical device, and it won't tell you what to take or how much.
See your whole stack on one decay-aware timeline.
Get early access to StackSenseFAQ
What does half-life actually mean for tracking?
Half-life is the time it takes for a logged amount to fall by half, based on published research references. It's a modeled curve, not a measured blood level, and not a countdown to zero. For tracking, it's mainly useful for spacing doses consistently and reading whether a change lines up with a compound still being active or mostly cleared.
Why do some peptides need daily dosing and others weekly?
Dosing interval usually tracks half-life. Compounds with a half-life measured in minutes to hours, like ipamorelin or GHK-Cu, tend to run on daily schedules. Compounds with a half-life measured in days, like retatrutide or CJC-1295 with DAC, tend to run weekly or less often. Logging the actual time, not just the day, is what makes this visible in your own data.
Is CJC-1295 with DAC the same as CJC-1295 without DAC?
No, and mixing them up in a log is one of the more common tracking mistakes. The DAC version binds to albumin and runs on a multi-day half-life, while the no-DAC version (sometimes called Mod GRF 1-29) clears in around 30 minutes. They're dosed on completely different schedules, so logging which version you're using matters as much as logging the dose.
Is this dosing or medical advice?
No. This is a reference for organizing your own tracking data using published half-life research. It is not a recommendation for what to take, how much, or how often. Anything involving your own protocol belongs with a qualified professional.
This is a tracking and organization guide only. It is not medical, dosing, or treatment advice, and StackSense is not a medical device. Work with a qualified healthcare professional on anything you put in your body.