Technical SEO
Core Web Vitals
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What is Core Web Vitals?
Core Web Vitals are a set of specific, user-centered metrics defined by Google to measure real-world page experience. The current set includes Largest Contentful Paint (LCP) for loading performance, Cumulative Layout Shift (CLS) for visual stability, and Interaction to Next Paint (INP) for interactivity. Google uses these metrics as part of the page experience signals its core ranking systems consider.
Core Web Vitals are measured using field data from the Chrome User Experience Report (CrUX) — reflecting real user experiences — and lab data from tools like Lighthouse. Each metric has defined thresholds: "Good," "Needs Improvement," and "Poor." Sites must achieve "Good" ratings for all three metrics at the 75th percentile to pass the Core Web Vitals assessment, which is reported in Google Search Console.
Why it matters for SEO
Core Web Vitals are an official Google ranking factor that directly ties page experience to search performance. Poor scores, particularly on LCP and CLS, signal a degraded user experience that can suppress rankings — especially when competing pages in the same niche offer better performance.
Example
In Search Console, a news site's Core Web Vitals report shows mobile article pages as "Poor" because of layout shift. Ads load late and push the text down as people start reading. Reserving fixed-height slots for the ad units stops the shifting, CLS moves into the "Good" range in the field data over the following weeks, and reading is no longer interrupted.
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