How to check Core Web Vitals for free
Core Web Vitals are measured by Google's CrUX dataset, updated monthly with real-user data. Check field data free at PageSpeed Insights (pagespeed.web.dev) or in Google Search Console under Core Web Vitals. CrUX reports LCP, INP, and CLS. Sites with under 1,000 visits in 28 days may not appear in CrUX field data, use lab data instead.
What LCP, INP, and CLS scores does Google consider "good"?
Google publishes explicit thresholds for each metric. For LCP (Largest Contentful Paint), good is 2.5 seconds or under; needs improvement is 2.5 to 4 seconds; poor is above 4 seconds. For INP (Interaction to Next Paint), good is 200 milliseconds or under; needs improvement is 200 to 500 milliseconds; poor is above 500 milliseconds. For CLS (Cumulative Layout Shift), good is 0.1 or under; needs improvement is 0.1 to 0.25; poor is above 0.25. To pass the Core Web Vitals assessment, at least 75 percent of page views must fall in the "good" range for all three metrics. These thresholds come directly from web.dev/articles/vitals (Google, 2024).
Why does my Core Web Vitals score differ between PageSpeed Insights and Search Console?
PageSpeed Insights shows two data sources side by side: field data (real-user measurements from CrUX, the same data Google uses for ranking) and lab data (a simulated load run by Lighthouse in a controlled environment). Search Console shows only field data, aggregated at the URL group level across all pages with similar patterns. The differences you see are usually: (1) PageSpeed Insights runs against a single URL; Search Console averages across a URL group. (2) Lab data uses a fixed network speed and device profile; field data reflects your actual visitors' conditions. When they conflict, field data is what Google's ranking signal uses.
Which Core Web Vital should I fix first?
Start with LCP. It measures when the page's largest visible element finishes loading, which is usually the hero image or the main heading block. LCP is the metric most correlated with whether a visitor perceives a page as fast, and it is typically the most improvable: compress and properly size your hero image, serve it from a CDN, and add a preload hint. INP matters if your page has interactive elements that feel sluggish after load, JavaScript-heavy sites and pages with complex event handlers are the usual culprits. CLS is the most disruptive to the reading experience (content shifting under the reader's cursor), and the fastest fix is setting explicit width and height attributes on images and iframes so the browser reserves their space before they load. AuditLamp's free audit checks LCP, CLS, and a set of the most common causes for each.