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Core Web Vitals Explained

Advanced 9 min read Lesson 15 of 31

Core Web Vitals are Google’s metrics for real-world user experience. They measure loading, interactivity and visual stability.

The three metrics

  • LCP (Largest Contentful Paint) — loading. Aim for under 2.5 seconds.
  • INP (Interaction to Next Paint) — responsiveness. Aim for under 200 ms. (INP replaced FID in 2024.)
  • CLS (Cumulative Layout Shift) — visual stability. Aim for under 0.1.

Why it matters

Core Web Vitals are a confirmed (if small) ranking factor, and more importantly they affect conversions. A fast, stable page keeps users and earns more from the traffic you already have.

Pro tips

  • Measure with PageSpeed Insights and Search Console’s Core Web Vitals report.
  • Focus on field data (real users), not just lab scores.
  • Fix your slowest, highest-traffic templates first.

Common mistakes

  • Chasing a perfect lab score while real users still struggle.
  • Ignoring CLS caused by images and ads without dimensions.
  • Optimising the homepage but not the templates that get the traffic.
Summary

Core Web Vitals — LCP, INP and CLS — measure real user experience for loading, responsiveness and stability. They influence rankings and conversions.

Quick quiz

1. Which metric measures loading?
2. What replaced FID in 2024?
3. A good CLS score is?