Google's set of real-world performance metrics that measure page speed, interactivity, and visual stability. A direct ranking factor since 2021.
Core Web Vitals are a set of specific, measurable performance metrics that Google uses to evaluate user experience on web pages. They became an official Google ranking factor in May 2021. The three current Core Web Vitals are: Largest Contentful Paint (LCP) — how long it takes for the main content to appear; Interaction to Next Paint (INP) — how quickly the page responds to user interactions; and Cumulative Layout Shift (CLS) — how much the page layout moves around unexpectedly during load.
Google's thresholds for 'good' scores: LCP should be 2.5 seconds or less, INP should be 200ms or less, and CLS should be 0.1 or less. Pages that fail these thresholds are flagged as having 'poor' or 'needs improvement' scores in Google Search Console, and rank below pages that pass them for equivalent content quality. Google measures these metrics from real Chrome user data (called CrUX data), not just lab simulations.
For service business websites, LCP is usually the most impactful metric to improve. The LCP element is most commonly the hero image or a large heading in the above-the-fold section. Optimizing this image (compression, next-gen formats, preloading) directly improves LCP scores. CLS issues often arise from images without defined dimensions or elements that shift as fonts or ads load. INP issues typically come from heavy JavaScript execution.
Core Web Vitals data is available in Google Search Console under the 'Core Web Vitals' report, which shows which pages are 'Good,' 'Needs Improvement,' or 'Poor' based on real user data. PageSpeed Insights provides page-level lab and field data. For most business websites, addressing Core Web Vitals is one of the highest-ROI technical SEO investments available.