Core Web Vitals
What is Core Web Vitals?
Core Web Vitals are Google's quantified user experience metrics, used as ranking signals in Google Search since 2021. For mobile web and PWA testing, they are the primary performance benchmark. LCP (Largest Contentful Paint) measures loading: the time from navigation start to when the largest content element is rendered. INP (Interaction to Next Paint) replaced FID in 2024, it measures responsiveness by tracking the delay between a user interaction and the next paint. CLS (Cumulative Layout Shift) measures visual stability: the sum of unexpected layout shifts during the page lifecycle. Google defines 'good' thresholds as LCP < 2.5s, INP < 200ms, CLS < 0.1.
Related terms
Core Web Vitals, frequently asked questions
Core Web Vitals apply specifically to web pages (including mobile web and Progressive Web Apps). For native iOS and Android apps, the analogous metrics are: Cold Start time (equivalent to LCP), UI thread frame rate / jank rate (equivalent to INP), and layout stability during scroll. Native app performance is not measured by Google's Core Web Vitals tooling.
Google uses Core Web Vitals as a ranking signal for mobile search results via the Page Experience update. Pages with 'Good' scores on all three vitals receive a ranking boost. Critically, Google measures vitals using real user data from Chrome (the Chrome User Experience Report), not lab tests, so real-world mobile performance on mid-range Android devices is what determines the ranking signal.