Core Web Vitals are a set of three Google metrics that measure real-world loading, interactivity, and visual stability of a page.
The three metrics are Largest Contentful Paint, which times how quickly the main content renders; Cumulative Layout Shift, which measures unexpected movement of elements as the page loads; and Interaction to Next Paint, which captures how responsive the page feels to user input. INP replaced First Input Delay as a Core Web Vital in March 2024.
The "good" thresholds are LCP at or under 2.5 seconds, CLS at or under 0.1, and INP at or under 200 milliseconds, each assessed at the 75th percentile of page loads. Google uses field data from the Chrome User Experience Report for ranking, while lab tools like Lighthouse help diagnose causes. Core Web Vitals are a real but modest ranking factor within the broader page experience signals.
Because each metric has its own causes and fixes, the deep guides below cover them individually, including the important difference between field data and lab data.
Related: LCP guide, CLS guide, INP guide, Field vs lab data
Claude Vincent is a technical SEO consultant focused on crawlability, rendering, and AI-search visibility. He writes the field guides and case studies at SEO ProCheck, with a bias toward the durable, unglamorous work that decides whether search engines and AI answer engines can actually read and cite a site.
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