Core Web Vitals
Core Web Vitals are a set of three specific metrics defined by Google that measure real-world user experience on websites: loading performance (LCP), interactivity (INP), and visual stability (CLS).
Core Web Vitals are Google's official metrics for measuring user experience on the web. They consist of three specific measurements: Largest Contentful Paint (LCP), which measures loading speed; Interaction to Next Paint (INP), which measures responsiveness; and Cumulative Layout Shift (CLS), which measures visual stability. Google uses Core Web Vitals as a ranking factor in search results.
Each metric has specific thresholds. LCP should occur within 2.5 seconds of the page starting to load. INP should be under 200 milliseconds.
In practice
- An e-commerce site improved their LCP from 4.5s to 1.8s by optimizing hero images and implementing lazy loading, resulting in a 12% increase in conversion rates
- A news website fixed their CLS score (from 0.35 to 0.05) by adding width and height attributes to all images and reserving space for ads, reducing reader frustration with jumping content
- A SaaS marketing site improved all three Core Web Vitals to "good" status and saw a 15% increase in organic search traffic within three months
- A travel website with poor INP scores (500ms) optimized their JavaScript execution, bringing INP to 150ms and making the booking interface feel instant
Not sure how this applies to you?
A senior engineer walks your site, your search presence and the way enquiries reach you, then writes down the three things worth fixing first. You keep the document either way.