Technical SEO
What are Core Web Vitals and what are good scores?
Short answer
Core Web Vitals are three measures of real-user page experience: Largest Contentful Paint (loading, good at 2.5 seconds or less), Interaction to Next Paint (responsiveness, good at 200 milliseconds or less) and Cumulative Layout Shift (visual stability, good at 0.1 or less), judged at the 75th percentile of visits.
The three metrics
| Metric | Measures | Good | Poor |
|---|---|---|---|
| LCP, Largest Contentful Paint | When the main content appears | 2.5 s or less | Over 4 s |
| INP, Interaction to Next Paint | How quickly the page responds to input | 200 ms or less | Over 500 ms |
| CLS, Cumulative Layout Shift | How much the layout jumps | 0.1 or less | Over 0.25 |
How to measure
- Field data from real visitors: the Core Web Vitals report in Search Console and the Chrome UX Report.
- Lab data for fixing: Lighthouse and PageSpeed Insights.
Fixes that help most
- LCP: serve a right-sized hero image, preload it, cut render-blocking CSS and JavaScript, and use a fast host with compression and caching.
- INP: break up long JavaScript tasks and defer scripts you do not need at start.
- CLS: give images and videos width and height, reserve space for embeds and avoid inserting content above what is already on screen.
- Fonts: self-host fonts, subset them and use
font-display: swap.
How SageRank helps
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