Core Web Vitals are the three key metrics Google uses to measure page experience: LCP, INP and CLS. They aren’t a magic ranking button on their own; but a slow and unstable site negatively affects both users and crawling.
The three metrics
- LCP (Largest Contentful Paint): How quickly the page’s main content becomes visible. Good target: under 2.5 seconds.
- INP (Interaction to Next Paint): How quickly the page responds to user interaction. Good target: under 200 milliseconds.
- CLS (Cumulative Layout Shift): How much content shifts while the page loads (that annoying “jump”). Good target: under 0.1.
How to improve them
For LCP:
- Optimize images and serve them at the right size.
- Improve server response time and hosting.
- Load critical content first; defer unnecessary resources.
For INP:
- Reduce and split heavy JavaScript.
- Review third-party scripts; remove unnecessary ones.
For CLS:
- Give fixed sizes to images and ads.
- Load fonts in a way that doesn’t cause shifting.
- Don’t inject content on top of existing content after load.
Why does it matter?
A slow site loses visitors and lowers conversion. Also, if the bot gets slow responses, crawl efficiency drops. Speed isn’t just a metric; it’s part of both the user experience and technical SEO health.
Measurement tools
You can measure Core Web Vitals with real user data (Search Console) and lab tools (PageSpeed Insights, Lighthouse). Measure first, prioritize issues, then improve.
Summary
Core Web Vitals measure page experience through speed (LCP), responsiveness (INP) and visual stability (CLS). Improving these metrics positively affects both users and visibility. To see your site’s technical state, you can request a technical pre-review.