Performance
Core Web Vitals
Google's three measures of real-user experience: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (stability).
Each metric has a published “good” threshold, assessed at the 75th percentile of page visits, with mobile and desktop measured separately (web.dev):
- Largest Contentful Paint (LCP): how quickly the main content appears. Good is 2.5 seconds or less.
- Interaction to Next Paint (INP): how quickly the page responds to clicks, taps and key presses. Good is 200 milliseconds or less. INP replaced First Input Delay in March 2024.
- Cumulative Layout Shift (CLS): how much content moves unexpectedly. Good is 0.1 or less.
Google measures these from real Chrome users through the Chrome User Experience Report, so a high Lighthouse score in a lab test does not guarantee a pass. Search Console’s Core Web Vitals report and PageSpeed Insights show the field data for your own pages.
Google uses Core Web Vitals in ranking as part of page experience, but they are one signal among many and do not outweigh relevant, useful content. The bigger payoff is usually with visitors, because pages that load quickly and respond at once are easier to use and to buy from. Set the thresholds as requirements at the start of a build, when meeting them costs least.
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