Core Web Vitals
Core Web Vitals are a set of three user-experience metrics Google uses as ranking signals: LCP (loading), INP (interactivity), and CLS (visual stability). They are part of the Page Experience update.
Reviewed by Alexander Yarovenko · Updated: 2026-09-18
What are Core Web Vitals?
Core Web Vitals (CWV) are a specific subset of web performance metrics that Google has identified as critical for user experience. They became a Google ranking signal in June 2021 as part of the Page Experience update. As of 2024, the three Core Web Vitals are:
| Metric | Measures | Good | Poor |
|---|---|---|---|
| LCP (Largest Contentful Paint) | Loading performance | < 2.5s | > 4.0s |
| INP (Interaction to Next Paint) | Interactivity / responsiveness | < 200ms | > 500ms |
| CLS (Cumulative Layout Shift) | Visual stability | < 0.1 | > 0.25 |
Note: INP replaced FID (First Input Delay) as a Core Web Vital in March 2024. INP measures responsiveness to all interactions during the page visit, not just the first.
Lab Data vs Field Data
- Lab data — simulated in a controlled environment (Lighthouse, PageSpeed Insights). Useful for debugging; available instantly.
- Field data (CrUX) — real user measurements collected by Chrome. What Google actually uses for rankings. Available in Search Console and PageSpeed Insights.
Where to Check Core Web Vitals
- Google Search Console → Core Web Vitals report (field data, segmented by mobile/desktop)
- PageSpeed Insights — combines lab + field data with specific recommendations
- Chrome DevTools → Performance panel (lab data)
- CrUX Dashboard (Looker Studio) — historical field data trends
Core Web Vitals and Rankings
Google has confirmed CWV as a tiebreaker signal — when content quality is equal between two pages, the one with better CWV may rank higher. The impact is most significant on mobile. A "Good" CWV status (all three metrics in the green range) is the target; pages in the "Poor" range are most at risk.
How to use this concept in SEO
Core Web Vitals summarize loading, responsiveness, and visual stability through LCP, INP, and CLS. Diagnose field data by page type and device before optimizing isolated laboratory scores.
Audit checklist
- Confirm that the implementation matches the page purpose and the user task.
- Check the HTTP response, rendered HTML, canonical, robots rules, and internal links together.
- Use Search Console and analytics to verify the result instead of relying on one crawler signal.
- Test a representative URL on mobile and desktop after deployment.
- Document the expected outcome so regressions can be detected in the next audit.
Practical example
A template with poor mobile LCP is traced to an oversized hero image and slow server response; both are fixed and monitored in CrUX and Search Console.
How to validate the result
Record the current crawl, indexation, performance, and traffic state before changing anything. Recheck the affected template and a representative URL after deployment, then monitor Search Console over the following crawl cycle. A technical change is complete only when the live response and Google’s observed state agree.