Core Web Vitals (CWV)
Google's three key metrics (LCP, INP, CLS) that measure real-world page experience.
Core Web Vitals are the three page-experience metrics Google uses: Largest Contentful Paint for loading, Interaction to Next Paint for responsiveness, and Cumulative Layout Shift for visual stability. Google grades them on field data from real Chrome users, so lab results can pass while the metrics Google actually uses do not.
Definition
Core Web Vitals are a set of real-world, user-centric metrics that Google uses to evaluate page experience. The three current CWV metrics are:
- LCP (Largest Contentful Paint) — measures loading performance. Target: under 2.5 seconds.
- INP (Interaction to Next Paint) — measures interactivity/responsiveness. Target: under 200ms.
- CLS (Cumulative Layout Shift) — measures visual stability. Target: under 0.1.
CWV data comes from the Chrome User Experience Report (CrUX) — real user measurements, not lab tests.
Why It Matters
CWV is a confirmed Google ranking factor since June 2021. Sites with good CWV scores get a ranking boost in mobile search results. More importantly, fast sites convert better — every 100ms delay reduces conversions by 7%.
Example
Run your site through SlapMyWeb to check CWV scores. A common issue: large hero images causing bad LCP. Fix: use WebP/AVIF format, add fetchpriority="high", and implement responsive srcset.
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