← Full peptide calculator
FREE TOOL
Estimate how a peptide builds up and clears with repeated dosing. Enter a half-life — or load a published reference value where one exists — plus your dose and interval, and this free calculator shows the build-up to steady state, how much carries over between doses, the time to reach steady state, and the washout after your last dose. Arithmetic and estimate only — not medical advice.
| Peptide | Half-life | Basis |
|---|---|---|
| Established (FDA-labeled) | ||
| Semaglutide | 168 h (~7 days) | FDA label — about 1 week (~168 h). |
| Tirzepatide | 120 h (~5 days) | FDA label — about 5 days (~120 h). |
| PT-141 (bremelanotide) | 2.7 h | Vyleesi FDA label — ~2.7 h (range 1.9–4.0 h). |
| Tesamorelin | 30 min | Egrifta FDA label — ~26–38 min. |
| Sermorelin | 12 min | ≈ 11–12 min after IV or SC dosing. |
| Investigational (PK published) | ||
| Retatrutide | 144 h (~6 days) | Phase 2/3 trials — about 6 days. Investigational. |
| Cagrilintide | 192 h (~8 days) | Trials — about 7–8 days (159–195 h). |
| Ipamorelin | 2 h | Research — roughly 1–2 h. |
| CJC-1295 (with DAC) | 168 h (~7 days) | Teichman 2006 — ~6–8 days. WITHOUT DAC it is only ~30 min. |
| No established human half-life | ||
| BPC-157 | Not established | No established human half-life — enter your own value. |
| TB-500 | Not established | No established human half-life — enter your own value. |
| GHK-Cu | Not established | No validated injectable human half-life — enter your own value. |
| KPV | Not established | No published human half-life; sometimes cited as roughly 2–4 h from non-human data — enter your own value. |
| Melanotan II | Not established | Human pharmacokinetics are poorly characterized — enter your own value. |
| Mazdutide | Not established | Long-acting (weekly), but no widely-published human half-life — enter your own value. |
| Survodutide | Not established | Long-acting (weekly), but no widely-published human half-life — enter your own value. |
One-compartment, first-order model: k = ln(2) ÷ half-life; accumulation = 1 ÷ (1 − e^(−k·interval)); steady state and washout ≈ 5 half-lives. Shows the estimated amount remaining in the body relative to one dose — not an absolute plasma concentration. Estimate and arithmetic only — not medical advice. Reference half-lives are approximate published figures; several research peptides have no established human half-life.
GLP-1 TITRATION PLOTTER
Plan a titration schedule and see the curve
Build a weekly dose-escalation plan for tirzepatide, semaglutide, or retatrutide — or enter your own half-life and steps — and watch the estimated relative blood level build week by week. Hover the curve to read any point. Arithmetic and estimate only — not medical advice.
FDA-label titration (Mounjaro / Zepbound). Half-life ≈ 5 days.
One-compartment, first-order weekly-dosing model: k = ln(2) ÷ half-life; each dose decays as e^(−k·t) and all doses are summed (superposition). Shows an estimated relative level, not an absolute plasma concentration (no volume-of-distribution or bioavailability modeling). Titration presets reflect common labeled/trial escalations; retatrutide is investigational. Estimate and arithmetic only — not medical advice. Verify against the product label and with a clinician.
Frequently asked questions
What is a peptide’s half-life?
The half-life is the time it takes for the amount of a compound in the body to fall by half. A short half-life clears quickly; a long one lingers and builds up with repeated doses. This calculator uses it to estimate accumulation and washout — it does not measure your individual levels.
How long until a peptide reaches steady state?
As a rule of thumb, repeated dosing reaches steady state after roughly five half-lives — the point where the amount carried over between doses stops rising. Enter a half-life and interval and the tool estimates the time to steady state for you.
Why don’t all peptides have a preset half-life?
Because several research peptides — including BPC-157, TB-500 and GHK-Cu — have no well-established human half-life in the published literature. Rather than invent a number, the tool marks them as “not established” and asks you to enter your own value.
Is this medical advice?
No. It is a general pharmacokinetic estimate and arithmetic tool only. It shows relative amounts, not your actual blood levels, and it does not recommend a dose or schedule. Always verify with a clinician, the product label, or a pharmacist.