Core Web Vitals in Search Console use field data: measurements from real visits, grouped by URL and device type. This is not a lab score or a single user’s result. A rolling 28-day window smooths short-term noise, so changes take time to appear.
Check each signal separately:
• LCP: 2.5s or less
• INP: 200ms or less
• CLS: 0.1 or less
A URL is rated Good, Needs improvement, or Poor based on the share of visits crossing these thresholds.
Fix patterns, not pages one by one. For LCP, improve server response and prioritize the main image. For INP, reduce JavaScript, long tasks, and heavy event handlers. For CLS, reserve space for images, ads, and embeds. Compare mobile and desktop separately.
Use lab tools to investigate causes, but let field data confirm the outcome. Start with Poor URLs on important templates, make one controlled change, then monitor whether the distribution improves—not just one test result.
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How to read the Core Web Vitals report—and fix the issues field data actually shows
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