Core Web Vitals

The three metrics and their thresholds

Google considers a page to pass when 75% of real visits (the 75th percentile) are "good", measured separately on mobile and desktop.

• LCP (Largest Contentful Paint): loading. Time until the largest visible element is painted, usually the main image or headline. Good: 2.5 seconds or less. Poor: over 4 seconds.
• INP (Interaction to Next Paint): responsiveness. How long the page takes to respond visually to clicks, taps and key presses throughout the visit. Good: 200 milliseconds or less. Poor: over 500 ms. It replaced FID (First Input Delay) in March 2024.
• CLS (Cumulative Layout Shift): stability. How much elements move while the page loads, for example a button that shifts when a banner appears. Good: 0.1 or less. Poor: over 0.25.

Field data vs lab data

What counts for Google is field data: real visits from Chrome users, collected in the Chrome UX Report (CrUX). Lab tools such as Lighthouse simulate a page load and are useful for diagnosis, but their numbers don't always match real-world ones. Lighthouse, for instance, can't measure INP because there are no real interactions; it uses Total Blocking Time as a proxy.

Where to check them

• Google Search Console, Core Web Vitals report: groups your URLs by status.
• PageSpeed Insights: field data for a URL or the whole origin, plus a lab diagnosis.
• Google's web-vitals library, to measure them in your own analytics.

Common causes of poor results on B2B websites

• Unoptimized or late-loading hero images (LCP).
• Too many third-party scripts: chat, analytics, heatmaps, ad pixels (INP).
• Cookie banners, web fonts or ads that push content down while loading (CLS).
• Images and videos without declared dimensions (CLS).

Related terms

• Above the fold
• Landing page

Sources

• web.dev, Web Vitals and Interaction to Next Paint (INP).
• Google Search Central, Understanding Core Web Vitals and Google search results.