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Core Web Vitals are Google’s set of user-experience metrics focused on loading, interactivity and visual stability. They help website owners investigate how real visitors experience important pages. Good metrics are useful goals, but they do not guarantee a search ranking or replace testing whether customers can complete key tasks.
LCP: loading performance
Largest Contentful Paint (LCP) measures when the largest visible content element is rendered. Large hero images, slow server responses, render-blocking resources and inefficient loading can delay it.
Possible improvements include optimising the main image, improving server response, reducing unnecessary blocking resources and ensuring critical content is discoverable early.
Possible improvements include optimising the main image, improving server response, reducing unnecessary blocking resources and ensuring critical content is discoverable early.
INP: responsiveness
Interaction to Next Paint (INP) assesses responsiveness across user interactions. Long-running JavaScript, heavy third-party scripts and excessive main-thread work can make clicks or taps feel delayed.
Review unnecessary scripts, split expensive tasks where appropriate, reduce unused code and test forms, menus and other interactive controls on representative devices.
Review unnecessary scripts, split expensive tasks where appropriate, reduce unused code and test forms, menus and other interactive controls on representative devices.
CLS: visual stability
Cumulative Layout Shift (CLS) measures unexpected movement of visible page elements. Images without reserved dimensions, late-loading ads, banners or injected content can cause layouts to jump.
Reserve space for images and embeds, use stable layout dimensions and handle dynamic banners so they do not unexpectedly push content around.
Reserve space for images and embeds, use stable layout dimensions and handle dynamic banners so they do not unexpectedly push content around.
Use field and lab data together
Field data represents real-user experiences over time and may be limited for low-traffic pages. Lab tools provide repeatable diagnostic tests but may not reproduce every real visitor’s device or network.
Use PageSpeed Insights and relevant Search Console reports to identify patterns, then test the specific page and change most likely to address the bottleneck.
Use PageSpeed Insights and relevant Search Console reports to identify patterns, then test the specific page and change most likely to address the bottleneck.
Prioritise business-critical pages
Start with landing pages, service pages, enquiry forms and checkout or booking flows. A homepage score alone may not reflect the experience across the whole site.
After changes, confirm that forms still work, content remains accessible and the site behaves correctly on mobile.
After changes, confirm that forms still work, content remains accessible and the site behaves correctly on mobile.
Frequently asked questions
What are the current Core Web Vitals?
The principal metrics are Largest Contentful Paint (LCP), Interaction to Next Paint (INP) and Cumulative Layout Shift (CLS). Check current Google guidance for thresholds and measurement details.
Do Core Web Vitals guarantee better rankings?
No. They are part of page experience considerations, but relevance, helpfulness, competition and many other factors influence search results.
Why does my score differ between tests?
Network conditions, device simulation, caching, server load, test location and page changes can affect lab results. Compare consistent tests and use field data where available.
