Core Web Vitals

Core Web Vitals is a set of Google-recommended metrics that aim to quantify the user experience of a website in terms of loading performance, visual stability, and interactivity. The three specific Core Web Vitals are:

  • Largest Contentful Paint (LCP) – Measures loading speed by reporting when the main content of a page is rendered. The target is < 2.5 seconds.
  • First Input Delay (FID) – Measures interactivity by reporting the delay between the user’s first tap/click and the time for the browser to respond. The target is < 100 milliseconds.
  • Cumulative Layout Shift (CLS) – Measures visual stability by quantifying sudden shifts in page layout as assets load in. The target is < 0.1.

Key facts:

  • Core Web Vitals represent Google’s guidance on web performance best practices that directly affect user experience.
  • Google is incorporating the Core Vitals into its search ranking algorithms – pages that meet targets will be rewarded.
  • Tools like PageSpeed Insights and Chrome User Experience Report measure Core Vitals performance.
  • Improving site speed, optimizing images, using content delivery networks, eliminating render-blocking resources, and employing best UX practices allows sites to target the metrics.
  • Core Web Vitals apply to both mobile and desktop sites but especially focus on mobile UX which is a growing emphasis for Google’s rankings.

Optimizing Google’s Core Web Vitals to deliver a fast, smooth, interactive website experience is becoming more important for overall SEO success.