When the page's main content (and its dateModified) last changed.
Each engine weights freshness differently. Perplexity has the tightest window (~30 days); ChatGPT the widest (~90).
Used to translate retention into citations at risk.
Models an exponential freshness half-life per engine (Perplexity ~30d, Gemini ~60d, Google AIO ~75d, ChatGPT ~90d), grounded in the 30-day-half-life research: pages unrefreshed for 90+ days are ~3.2x more likely to lose citations. Directional, not a forecast.
How this works
AI engines increasingly weight freshness. Pages left unrefreshed for 90+ days are roughly 3.2x more likely to lose their AI citations, and over 80% of citations on commercial queries come from pages updated within the prior 30 days. Each engine applies a different window, so this tool models an exponential freshness half-life per engine and projects retention forward.
Use the recommended refresh date as a trigger to update one statistic, the dateModified field, and one section heading, enough to re-enter the citation window.