Core Web Vitals
A set of three Google page experience metrics: Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS). Used as ranking signals since 2021.
What are Core Web Vitals?
Core Web Vitals are a set of three real-world user experience metrics that Google uses to assess the load performance, interactivity, and visual stability of a web page. They were introduced as ranking signals in the Page Experience update in 2021 and have been updated since: Interaction to Next Paint (INP) replaced First Input Delay (FID) as the interactivity metric in March 2024. Pages that score well on Core Web Vitals are considered to offer better user experiences and receive a modest ranking benefit.
The three Core Web Vitals metrics
- Largest Contentful Paint (LCP): Measures how long it takes for the largest visible content element (typically a hero image or heading) to load. Good LCP is under 2.5 seconds. This is the load performance metric.
- Interaction to Next Paint (INP): Measures the time from a user interaction (click, tap, keyboard input) to when the browser renders the next frame. Good INP is under 200 milliseconds. This is the interactivity metric.
- Cumulative Layout Shift (CLS): Measures unexpected layout shifts: how much page elements move around during loading. A good CLS score is under 0.1. This is the visual stability metric.
How to measure Core Web Vitals
Core Web Vitals can be measured in two ways. Lab data (simulated measurements) is available through tools like Google PageSpeed Insights and Lighthouse. Field data (real user measurements) is collected from Chrome users and reported in Google Search Console's Core Web Vitals report. Field data is what Google uses for ranking purposes. A page may have good lab scores but poor field scores if real users on slower devices or connections experience worse performance.
How to improve Core Web Vitals
- LCP: Preload the hero image, use a CDN for image delivery, avoid large hero images, and ensure server response times are fast.
- INP: Minimise JavaScript execution time, break up long tasks, and defer non-critical scripts.
- CLS: Always specify width and height attributes for images and iframes, avoid dynamically injected content above existing content, and use transform animations instead of layout-triggering properties.
FAQ
Common Questions
Core Web Vitals are a tiebreaker ranking signal. On queries where multiple pages have similar relevance and quality, good CWV can provide a ranking advantage. However, content relevance and quality (E-E-A-T) consistently outweigh page experience signals. Poor CWV rarely suppresses a highly relevant, authoritative page significantly.
Google Search Console provides field data CWV for your site under Experience > Core Web Vitals. Google PageSpeed Insights provides both lab and field data for individual URLs.
Indirectly. Page experience does not directly affect AI citation probability in the way content quality does. However, pages with very poor performance may not be crawled as efficiently, which can affect indexing and therefore the pool of content available for AI citation.
Glossary