The common assumption about SteroidPlotter — that it is for anabolic steroids and you will need something else for a GLP-1 — is wrong. On 17 September 2026 its compound list included semaglutide, tirzepatide and retatrutide, and its homepage linked preset protocols for all three.
So the honest comparison is not "it does not cover your drug". It is narrower than that, and it comes down to what a plotted curve is allowed to claim.
What SteroidPlotter is
It plots estimated blood concentration over time. You pick compounds, doses, start and end weeks and an injection frequency, and it draws the resulting curves on one chart — several compounds at once, with offsets, which is what makes it a cycle planner rather than a single-drug graph.
Its library is wide: testosterone esters (enanthate, cypionate, propionate, phenylpropionate, isocaproate, decanoate, undecanoate), nandrolone, primobolan, anavar, trenbolone acetate, HGH, HCG, aromatase inhibitors and SERMs, estradiol and progesterone — and the GLP-1 drugs.
It ships preset protocols, linked from the homepage and attributed to "SteroidPlotter Admin". The two for approved drugs are titled "Semaglutide Recommended Progression" and "Tirzepatide Recommended Progression". The semaglutide preset steps 0.25 mg weekly for weeks 1–4, 0.5 mg for 5–8, 1 mg for 9–12, 1.7 mg for 13–16 and 2.4 mg from week 17, which is the approved escalation. The tirzepatide preset steps 2.5 / 5 / 7.5 / 10 / 12.5 / 15 mg in four-week blocks, which is also the approved escalation.
It is explicit about what it is. Its own note reads: "We aim to make our calculator as useful as possible based on publicly available studies and data. However, there are significant limitations, assumptions are made, and a simplified pharmacokinetic model is used. The half-lives and pharmacokinetic variables used are estimates and will differ between individuals. This tool is for entertainment only and should not be used to make medical decisions."
What it does better than this site
- Its compound coverage is far wider than ours and always will be. If you want to plot testosterone cypionate against trenbolone acetate, this site has nothing for you and SteroidPlotter does it well.
- Multi-compound overlay with per-compound start weeks, end weeks and frequencies is a genuinely good piece of tool design. Plotting one drug is easy; plotting five that start at different times on one axis is the hard part, and it handles it.
- Its disclaimer is more direct than most. Naming your own model as simplified, your half-lives as estimates and your tool as entertainment is more honest than the usual silence.
- Its presets for the two approved GLP-1 drugs match the approved escalation schedules rather than inventing one.
Where it falls short
- No half-life on the site carries a source. The note says the values come from publicly available studies and data, but no study, label or figure is named anywhere on the page, so there is no way to check any curve you are shown. Semaglutide's approximately one-week half-life and tirzepatide's approximately five days are both printed in their FDA labels; a plotting tool can cite them.
- One preset publishes a dosing progression for a drug that has no approved dose anywhere. The "Retatrutide Protocol" preset encodes 2 mg weekly for weeks 1–4, 4 mg for 5–8, 6 mg for 9–12 and 8 mg for 13–24, under the byline "SteroidPlotter Admin". Retatrutide is not approved by the FDA, EMA, MHRA, TGA or Health Canada; no regulator or manufacturer publishes a schedule for it, and the phase 2 trial is the only place its doses appear at all. Its two approved-drug presets are labelled "Recommended Progression"; this one is labelled "Protocol". Either word reads as guidance to someone who has just drawn the curve, whatever the disclaimer at the bottom of the page says.
- A second preset, "Peptide Weight Loss Protocol", stacks HGH with tirzepatide and retatrutide. There is no published trial of that combination.
- "For entertainment only" and a chart precise to the milligram are hard to hold at the same time. We think the disclaimer is honest; we also think it does not survive contact with a reader who has already drawn the curve.
Side by side
How this was checked
Loaded steroidplotter.com on 17 September 2026 and read the compound list, the preset protocol links and the site's own note in the page source.
Everything on this page about SteroidPlotter describes what it was doing on September 17, 2026. Other people’s products change without telling us, so nothing here is repeated from a third party’s summary and nothing is left undated. If you find a claim that no longer holds, it is wrong and it will be fixed.
SteroidPlotter is not affiliated with FreePeptideCalc in any way. There is no partnership, endorsement or sponsorship in either direction, and the name is used here only to identify the tool being compared.
What this site offers instead
- GLP-1 plotter — Serum level over time for the GLP-1 drugs, with the half-life behind each curve traced to its label.
- How long a GLP-1 stays in your system — The half-lives themselves, per compound, with what each label does and does not state.
- Retatrutide status — Why this site publishes retatrutide's half-life but not a dosing schedule.