Web & SEO
What is core Web Vitals?
Core Web Vitals are the three metrics Google uses to measure real-world page experience: how fast the main content loads, how quickly the page responds to input, and how much the layout shifts while loading.
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Technical definition
Core Web Vitals are a set of field metrics collected from real user visits, used by Google as page experience ranking signals:
- Largest Contentful Paint (LCP): time until the largest visible element has rendered. Measures perceived load speed.
- Interaction to Next Paint (INP): responsiveness to user input across the visit. Replaced First Input Delay in March 2024.
- Cumulative Layout Shift (CLS): how much visible content moves unexpectedly during loading.
Each metric has good, needs-improvement, and poor thresholds, assessed at the 75th percentile of visits. Verify current thresholds against Google's documentation, since both metrics and cutoffs have been revised.
In plain terms
Core Web Vitals measure three annoyances: the page took too long to show up, it did not react when you tapped, and it moved while you were reading it.
Google measures these on real visits to your site rather than in a lab, so the score reflects what your customers experience.
Why it matters
These are ranking signals, but the ranking effect is not the main reason to care. The behavior is. A visitor who taps a button that does not respond leaves, and a layout that jumps as they read costs you the sale before Google gets involved.
The common causes for a small business site are predictable. Uncompressed images, usually a photo straight off a phone, cause most LCP failures. Images and ads without reserved space cause most layout shift. Too much script, often from tracking and chat widgets stacked over time, causes most responsiveness problems.
That also makes the fixes predictable: size and compress images, reserve space for anything that loads late, and remove third-party scripts you are not using.
