Peptide Half-Life Calculator & Decay Simulator
This calculator models one-compartment pharmacokinetic decay: concentration falls by half each elimination half-life. For tirzepatide (~120 h half-life), steady state is approached after approximately 5 half-lives (~25 days) of consistent weekly dosing. Select a compound from our database or enter a custom half-life.
How half-life affects concentration
After each dose, concentration decays exponentially: C(t) = C₀ × e−kt, where k = ln(2) / t½. Repeated doses accumulate until elimination matches input — approximately 5 half-lives to reach ~97% of steady state. Trough level (just before the next dose) divided by peak indicates fluctuation across the dosing interval.
Model your curve in the Halflife app
Log injections and see concentration curves for 45 compounds with citation-backed half-life data.
Download on App StoreFAQ
What is tirzepatide half-life? Approximately 5 days (120 hours) per FDA NDA 215866. Steady state in ~4–5 weeks of weekly dosing.
How long until steady state? About 5 × half-life. Weekly GLP-1s typically reach steady state in 4–6 weeks.
Tirzepatide PK BPC-157 PK Reconstitution calculator All tools
Simplified one-compartment model for education only. Not medical advice. Methodology