GLP-1 Half-Life Calculator
Compare GLP-1 half-lives and visualize active blood levels over time. Switch compounds in the calculator below to compare PK curves side by side.
Peak Level
1 mg
Half-Life
7.0 days
Steady State
~5 weeks
Full Clearance
~36 days
Semaglutide: GLP-1 receptor agonist used for weight management and type 2 diabetes. Available as Ozempic (diabetes) and Wegovy (weight loss).
For educational and research purposes only. This calculator provides estimates based on standard formulas.
Always verify calculations with your healthcare provider before use. We assume no liability for dosing errors, adverse events, or outcomes resulting from use of this tool.
GLP-1 half-life comparison
| Compound | Brand | Half-life | Schedule | Steady state |
|---|---|---|---|---|
| Semaglutide | Ozempic, Wegovy | ~7 days | Weekly | ~5 weeks |
| Tirzepatide | Mounjaro, Zepbound | ~5 days | Weekly | ~4 weeks |
| Retatrutide | Phase 3 (not approved) | ~6 days | Weekly | ~4–5 weeks |
| Dulaglutide | Trulicity | ~5 days | Weekly | ~4 weeks |
| Liraglutide | Saxenda, Victoza | ~13 hours | Daily | ~3 days |
What half-life actually tells you
Half-life is the time it takes for the concentration of a drug in your blood to drop by 50 percent. For GLP-1 medications it determines three things you actually experience: how often you have to inject, how flat or peaky your weekly levels feel, and how long the drug keeps working after your last dose.
The big design split among GLP-1s is between liraglutide (a first-generation compound that clears quickly and requires daily dosing) and the modern once-weekly GLP-1s. Once-weekly compounds use either albumin binding (semaglutide, tirzepatide, retatrutide) or Fc-fusion (dulaglutide) to extend the half-life into the multi-day range. That is what makes weekly dosing pharmacologically clean.
Steady state is the point at which weekly intake equals weekly clearance. It takes about 4 to 5 half-lives to get there. That is also the window for full washout after you stop. For semaglutide at 7 days, both numbers land at roughly 5 weeks. For tirzepatide at 5 days, both land at 4 weeks. For liraglutide at 13 hours, it is 3 days.
Longer half-life is not automatically better. It produces flatter weekly levels, which usually means smoother GI side effect profiles. But it also means slower wash-in (you wait longer to feel a dose change) and slower wash-out (you can't pivot fast if you have a side effect issue). Choose by what your prescriber recommends, not by half-life alone.
Frequently asked questions
Why do GLP-1 half-lives vary so widely?
Newer once-weekly GLP-1s (semaglutide, tirzepatide, dulaglutide, retatrutide) use albumin binding or Fc-fusion to extend their half-life into the multi-day range. Liraglutide, the older once-daily GLP-1, lacks that engineering and clears in roughly half a day.
Which GLP-1 has the longest half-life?
Among approved compounds, semaglutide at approximately 7 days. Retatrutide (currently in Phase 3 trials) sits between tirzepatide and semaglutide at approximately 6 days. Dulaglutide and tirzepatide are both approximately 5 days. Liraglutide is 13 hours.
Does a longer half-life mean better results?
Not directly. The compound's intrinsic efficacy at its target receptors matters far more than half-life alone. Half-life primarily affects dosing convenience, peak-to-trough variance, and washout duration.
How quickly does each GLP-1 reach steady state?
Roughly 4 to 5 half-lives. Liraglutide: about 3 days. Tirzepatide, dulaglutide: about 4 to 5 weeks. Semaglutide: about 5 weeks. Retatrutide: about 4 to 5 weeks.
How long does each GLP-1 stay in your system after stopping?
Clinically meaningful exposure ends at roughly 4 to 5 half-lives. Liraglutide washes out in 2 to 3 days. Tirzepatide takes 4 to 5 weeks. Semaglutide takes 5 to 7 weeks.
For deeper compound-specific math, open the semaglutide or tirzepatide half-life pages.
Track your real GLP-1 PK curve
Regimen logs each weekly injection and projects your personal active-level curve, plus weight, sleep, and heart rate correlation.
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