Core Web Vitals

What Core Web Vitals measure

Core Web Vitals are three measurements Google uses to describe a page's real-world user experience. LCP (Largest Contentful Paint) covers loading, INP (Interaction to Next Paint) covers responsiveness and CLS (Cumulative Layout Shift) covers visual stability. INP replaced the older FID metric in March 2024. Google explains how they relate to Search in its Core Web Vitals documentation.

How to measure them

Search Console's Core Web Vitals report groups your URLs into good, needs improvement and poor, based on data from real Chrome users. PageSpeed Insights shows the same field data for a single page, plus lab tests that suggest fixes. Small sites may not have enough visits for field data, so lab results are the fallback.

Common causes of a poor result

• Chasing a perfect lab score while real users are fine.
• Testing only on fast office broadband.
• Installing extra plugins to "speed things up" that add more code.
• Forgetting that third-party chat widgets, trackers and embeds often cause the worst problems.

What a fix looks like

A bridal shop's home page opens with a huge, uncompressed video. On a phone, the main image takes ages to appear and the page jumps as banners load. Swapping the video for a compressed image and reserving space for the banner fixes both problems, and fewer visitors leave straight away.

Why speed and stability matter

Google says good Core Web Vitals line up with what its ranking systems reward, but that great page experience alone won't make a weak page rank. The bigger reason to care is customers. Slow, jumpy pages lose enquiries, especially on mobile data.

Other speed and experience terms

• LCP: Largest Contentful Paint: how quickly the main content of a page loads.
• INP: Interaction to Next Paint: how quickly a page responds when people interact with it.
• CLS: Cumulative Layout Shift: how much a page's layout jumps around while it loads.
• UX and SEO: Overlap where usability, speed and clarity support search performance.