Core Web Vitals are Google's key metrics for measuring user experience, and they play a crucial role in how your website ranks in search results.
In 2021, Google introduced Core Web Vitals as part of its ranking algorithm – a clear signal that user experience (UX) is now a critical part of SEO. But what are Core Web Vitals, and why should you care?
What are core web vitals?
Core Web Vitals are a set of three metrics that measure real-world user experience for loading speed, interactivity, and visual stability:
Largest Contentful Paint (LCP) – measures how long it takes for the largest element (e.g. image or text block) to load. Good: under 2.5 seconds
First Input Delay (FID) – measures how responsive a site is to a user’s first interaction (like clicking a button). Good: under 100 milliseconds
Cumulative Layout Shift (CLS) – measures how much the layout shifts unexpectedly while loading. Good: less than 0.1
Why do Core Web Vitals matter for SEO?
These metrics affect how users perceive your site. If your site is slow or jumps around as it loads, users will bounce, and Google will notice.
Key reasons they impact SEO:
- Google uses Core Web Vitals in its ranking algorithm
- Better scores improve user engagement, bounce rates, and conversions
- Google’s Page Experience report includes them as a quality signal
How to measure your Core Web Vitals
You can check your Core Web Vitals using tools such as:
- PageSpeed Insights
- Google Search Console
- Chrome DevTools
- Lighthouse
These tools offer lab and field data to help prioritise what to fix.
How to improve your Core Web Vitals
- LCP: optimise images, use faster hosting/CDNs, and remove render-blocking resources.
- FID: minimise JavaScript, use web workers, and defer unused scripts.
- CLS: always define image/video dimensions and avoid dynamic content shifts.
In summary
Core Web Vitals are more than just technical benchmarks, they reflect real user experience. Optimising them helps keep Google happy, meaning your site will rank more highly, and it will keep users happy, as the site will load faster.
