Google's Core Web Vitals have become one of the most important ranking factors for SEO. If your website is slow, provides a poor user experience, or shifts around while loading, you're likely losing both rankings and customers.
What Are Core Web Vitals?
Core Web Vitals are a set of specific factors that Google considers important in a webpage's overall user experience. They consist of three specific page speed and user interaction measurements.
Understanding Each Metric
LCP (Largest Contentful Paint)
LCP measures the time it takes for the largest content element visible in the viewport to render. This could be an image, video, or large block of text.
| Rating | LCP Time |
|---|---|
| Good | ≤ 2.5 seconds |
| Needs Improvement | 2.5 - 4.0 seconds |
| Poor | > 4.0 seconds |
INP (Interaction to Next Paint)
INP measures the responsiveness of a page by tracking the latency of all click, tap, and keyboard interactions throughout a user's visit.
| Rating | INP Time |
|---|---|
| Good | ≤ 200 milliseconds |
| Needs Improvement | 200 - 500 milliseconds |
| Poor | > 500 milliseconds |
CLS (Cumulative Layout Shift)
CLS measures visual stability — how much the page layout shifts unexpectedly during loading. Nothing annoys users more than clicking a button just as it moves.
| Rating | CLS Score |
|---|---|
| Good | ≤ 0.1 |
| Needs Improvement | 0.1 - 0.25 |
| Poor | > 0.25 |
Optimization Strategies
Improving LCP
Optimize Images
Use modern formats (WebP, AVIF), proper sizing, and lazy loading for below-the-fold images.
Use a CDN
Serve assets from servers geographically close to your users.
Preload Critical Resources
Use <link rel="preload"> for fonts, hero images, and critical CSS.
Eliminate Render-Blocking Resources
Defer non-critical JavaScript and inline critical CSS.
Improving INP
- Minimize JavaScript: Remove unused code and split bundles
- Defer Long Tasks: Break up heavy computations using requestIdleCallback
- Optimize Event Handlers: Keep them fast and debounce when appropriate
- Use Web Workers: Offload heavy processing to background threads
Improving CLS
- Set Dimensions on Media: Always include width and height attributes on images and videos
- Reserve Space for Ads: Use placeholders for dynamically loaded content
- Avoid Inserting Content Above Existing: New content should push down, not up
- Use CSS Transform for Animations: Transforms don't cause layout shifts
Measuring Your Site
Use these tools to measure and monitor your Core Web Vitals:
- PageSpeed Insights: Google's official tool with both lab and field data
- Chrome DevTools: Performance panel for detailed analysis
- Lighthouse: Built into Chrome, provides comprehensive audits
- Search Console: Core Web Vitals report shows issues across your site
Sites that meet Core Web Vitals thresholds see 24% less abandonment during page load and convert significantly better than slower competitors.
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