Core Web Vitals are a set of three performance metrics Google uses to measure the real-world user experience of a web page: how fast it loads, how quickly it responds to interaction, and how stable it is visually while loading.
What are the three Core Web Vitals metrics?
Largest Contentful Paint (LCP): measures loading performance. It tracks how long it takes for the largest visible element on the page, typically a hero image or main heading, to appear. Google's threshold for a good score is under 2.5 seconds.
Interaction to Next Paint (INP): measures responsiveness. It tracks how quickly the page responds when a user interacts with it, such as clicking a button. A good score is under 200 milliseconds.
Cumulative Layout Shift (CLS): measures visual stability. It tracks how much page elements shift unexpectedly as the page loads. A good score is below 0.1.
Why did Google make Core Web Vitals a ranking factor?
Pages that load slowly, respond poorly to interaction, or shift layout unexpectedly create a poor user experience. Google introduced Core Web Vitals as ranking signals because it wants to direct users to pages that perform well, not just pages with relevant content. They form part of a broader set of signals Google calls Page Experience.
[Screenshot: Google Search Console Core Web Vitals report showing pass, needs improvement, and poor URL counts for both mobile and desktop. Alt text: Google Search Console Core Web Vitals report showing mobile and desktop performance breakdown by status.]
How do I check my Core Web Vitals scores?
Core Web Vitals data is available in Google Search Console under the Experience section, which shows real-user field data from actual visitors to your site. Google PageSpeed Insights provides both lab and field data for individual URLs. In Thailand, mobile scores are worth monitoring closely, as mobile accounts for the majority of web traffic across most industries and connection speeds vary considerably between users and regions.
What commonly causes poor Core Web Vitals scores?
Poor LCP is most commonly caused by large unoptimised images, slow server response times, or render-blocking scripts and stylesheets. Poor INP is typically caused by heavy JavaScript execution that blocks the browser from responding quickly. Poor CLS is usually caused by images or ads without defined dimensions, or content loading above existing elements and pushing them down the page.
Do Core Web Vitals scores directly affect rankings?
Core Web Vitals are a confirmed but relatively minor ranking factor. Content quality and relevance will outweigh performance scores for most queries. In competitive searches where multiple pages are similarly relevant, a strong Page Experience score can be a differentiator. More practically, improving Core Web Vitals almost always improves conversion rates and reduces bounce rates, which benefits overall SEO performance indirectly.
Related KB articles:
• What is Technical SEO
• The Importance of Website Speed and How to Improve It
• Google Search Console: A Quick Guide
External links:
• Google PageSpeed Insights
• Google's Core Web Vitals documentation