Core Web Vitals

Interaction to Next Paint replaced First Input Delay as the third vital on 12 March 2024^[5], widening the responsiveness measure from the first interaction to every interaction on the page. Because the threshold sits at the 75th percentile, a page is rated good only when three quarters of its real loads are^[4].

Google's documentation ties the vitals to its core ranking systems without quantifying the weight^[6]. Google has also said page experience is one signal among many, that query intent and relevance are far stronger, and that a page with subpar experience can still rank highly on great content^[7]. John Mueller has called it a real ranking factor and more than a tie-breaker, while stating that it does not replace relevance^[8].

In July 2025 field data, 48% of mobile sites met all three thresholds at once^[9]. Loading is the metric that fails most: 62% of mobile pages reached a good LCP, against 74% on desktop^[10].

A study of 107,352 pages appearing in AI Overviews and AI Mode found only weak correlations with AI visibility, between -0.12 and -0.18 for LCP and -0.05 to -0.09 for CLS^[11]. Its conclusion is that the vitals act as a constraint and not a growth lever: passing creates no advantage, severe failure creates a disadvantage^[12]. Speed still has an indirect effect through crawling, since Google states that pages it can load and render faster let it read more of a site^[13]. A vendor blog puts an AI crawler abandonment window at one to five seconds, without citing a measurement for it^[14].

For an operator chasing citations the vitals are a floor, not a lever. The 107,352-page study found passing thresholds conferred no AI visibility advantage while severe failure was a disadvantage^[12], which makes them worth fixing when broken and not worth optimising past good. The indirect route is crawl: Google states that pages it can load and render faster let it read more of a site^[13], so speed buys coverage rather than ranking. Roughly half of mobile sites pass all three at once^[9], so failing is common rather than disqualifying.