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GLP-1 half-life calculator
How long does your GLP-1 stay in your system? Semaglutide clears in about 35 days, tirzepatide in about 25. Pick your medication for a calculator that estimates what's left from your last dose.
GLPMate estimates your real medication level every day from your dose history — free, for every medication below.
Half-life at a glance
| Active ingredient | Brands | Half-life | ~97% cleared |
|---|---|---|---|
| Semaglutide | Ozempic, Wegovy, Rybelsus | ≈ 7 days | ≈ 35 days |
| Tirzepatide | Mounjaro, Zepbound | ≈ 5 days | ≈ 25 days |
"~97% cleared" ≈ 5 half-lives from your last dose. A trace lingers longer but is rarely clinically meaningful.
This tool is for general education only. It is not medical advice, not a diagnosis, and not a substitute for your prescriber or pharmacist. Doses and schedules are set by your clinician — never start, stop or change a medication based on a web calculator.
Sources
- FDA Prescribing Information (label) for each product — clinical-pharmacology sections — elimination half-life per active ingredient
- First-order elimination model — remaining fraction = 0.5 ^ (time ÷ half-life)
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GLP-1 half-life questions
How long do GLP-1 medications stay in your system?
It depends on the drug. Semaglutide (Ozempic, Wegovy, Rybelsus) has a half-life of about 7 days, so it takes roughly 35 days to clear ~97% of a dose. Tirzepatide (Mounjaro, Zepbound) has a ~5-day half-life and clears in about 25 days. Pick your medication above to estimate what’s left from your last dose.
Which GLP-1 has the longest half-life?
Among the common weekly injectables, semaglutide has the longest half-life (~7 days), followed by tirzepatide (~5 days) and dulaglutide (~5 days). Longer half-lives mean smoother levels between doses and a slower build-up when you start.
Does a longer half-life mean the medication is stronger?
No. Half-life describes how fast a drug clears, not how potent it is. A long half-life just means steadier levels and a longer wash-out — it says nothing about how much weight you’ll lose or how strong the effect feels.
How accurate are these estimates?
They use standard first-order elimination (0.5 ^ time ÷ half-life) with half-lives from FDA clinical-pharmacology data. They’re educational single-dose estimates — real levels also depend on accumulation from earlier doses, your metabolism and kidney function. For your actual level on your real schedule, GLPMate models it in-app.