Conversion Rate Optimization

Core Web Vitals

Google's metrics for page experience: LCP (loading), FID (interactivity), CLS (visual stability).

1 min readLast updated Apr 2026

Google's metrics for page experience: LCP (loading), FID (interactivity), CLS (visual stability).

Why It Matters

Core Web Vitals are Google's official ranking factors for page experience. Poor scores hurt SEO rankings and correlate with poor conversion rates. They measure what users actually experience: can they see content (LCP), interact with it (FID), and trust it won't shift (CLS)?

Practical Example

Scenario

A beauty brand's product pages have poor CLS (0.28) due to late-loading product images that shift the layout. LCP is 4.2 seconds.

Calculation

After fixing: CLS improves to 0.05, LCP drops to 2.1 seconds

Result

Google Search Console shows 'Good' Core Web Vitals status. Organic traffic increases 12% as ranking improves, and on-site conversion improves 8% from better user experience.

Pro Tips

  • 1LCP: Optimize hero images and above-the-fold content loading
  • 2CLS: Set explicit dimensions for images and embeds to prevent layout shift
  • 3FID/INP: Minimize and defer JavaScript that blocks interactivity
  • 4Use Chrome DevTools and Lighthouse to diagnose issues before they affect users

Common Mistakes to Avoid

Ignoring CLS—layout shifts frustrate users and hurt rankings
Only testing in lab conditions, missing real-user experience issues
Adding third-party scripts (chat widgets, analytics) without measuring impact

Frequently Asked Questions

Related Terms

Page Speed

How quickly pages load. Each additional second decreases conversions by approximately 7%.