Definition
Core Web Vitals are three Google metrics for real-user experience: loading (LCP), responsiveness (INP) and visual stability (CLS).
Core Web Vitals explained
Google's Web Vitals program defines a small set of metrics that matter for every web page. The current Core Web Vitals, and the thresholds web.dev gives for a good experience, are:
- Largest Contentful Paint (LCP): the main content should load within 2.5 seconds.
- Interaction to Next Paint (INP): pages should respond to interactions within 200 milliseconds.
- Cumulative Layout Shift (CLS): layout shift should stay at 0.1 or less.
Each is assessed at the 75th percentile of page loads, separately for mobile and desktop, so a page passes only if most real visits meet the threshold. Field data from real Chrome users, published in the Chrome UX Report, is what Google Search uses; lab tests such as Lighthouse are useful for diagnosis but are not the same thing.
Core Web Vitals are part of how Google Search evaluates page experience. They rarely outweigh relevance, but slow, jumpy pages lose visitors and conversions whatever their rankings. Improving them usually means optimizing images, reducing JavaScript, reserving space for late-loading elements and speeding up the server.
Example
Your product pages load a large carousel image, a chat widget and several tracking scripts. Field data shows LCP well above 2.5 seconds on mobile and CLS above 0.1 as banners push content down. Compressing the hero image, delaying the chat widget and reserving banner space brings all three metrics into the good range.
Why it matters
Fast, stable pages keep more visitors and convert better, and good Core Web Vitals remove a potential drag on rankings.
Related service
Page Speed Optimization
We fix LCP, INP and CLS issues so pages load fast and respond quickly for real users.
Page speed and Core Web Vitals optimizationSources
- web.dev: Web Vitals (updated 31 Oct 2024)
Published by Vidern, founded and led by Malhar Shah. Updated .
Find out what's holding your site back
Get a free SEO audit with prioritized fixes, delivered within 48 hours.
Related terms
- LCP (Largest Contentful Paint)LCP (Largest Contentful Paint) measures how long the largest image, video or text block in view takes to render; 2.5 seconds or less is good.
- INP (Interaction to Next Paint)INP (Interaction to Next Paint) measures how quickly a page visibly responds to clicks, taps and key presses; 200 milliseconds or less is good.
- CLS (Cumulative Layout Shift)CLS (Cumulative Layout Shift) measures how much visible content unexpectedly moves on a page; a score of 0.1 or less is good.
- CrUX (Chrome UX Report)CrUX (the Chrome UX Report) is Google's public dataset of how real Chrome users experience websites, including their Core Web Vitals.
- PageSpeed InsightsPageSpeed Insights is Google's free tool that reports a page's real-user Core Web Vitals and runs a Lighthouse lab test with suggestions for improvement.