Glossary · SEO & Marketing

Core Web Vitals

Core Web Vitals are Google's page experience metrics, LCP, INP and CLS, that measure loading speed, responsiveness and visual stability for real users.

Updated October 6, 2026

Core Web Vitals are three user-centric metrics defined by Google: Largest Contentful Paint (LCP) for loading, Interaction to Next Paint (INP) for responsiveness and Cumulative Layout Shift (CLS) for visual stability. They are measured on real visits and assessed at the 75th percentile.

Why it matters

They feed into Google's page experience signals, and slow or jumpy pages frustrate visitors regardless of rankings. Content relevance still outweighs them, but they can be a tiebreaker.

Field data is available in the Chrome User Experience Report and in Search Console, while lab tools such as Lighthouse help you reproduce and debug specific problems.

Example

Google's published thresholds for a "good" result:

LCP   2.5 seconds or less
INP   200 milliseconds or less
CLS   0.1 or less

Common mistakes

  • Testing once in a lab tool and ignoring field data from real users.
  • Optimizing the home page only; vitals are assessed per page group.
  • Loading a large hero image without dimensions, which hurts both LCP and CLS.

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Keep reading

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