--- title: "Core Web Vitals: LCP, INP and CLS Explained" description: "Core Web Vitals are three metrics defined by Google to measure the user experience of a website: Largest Contentful Paint (LCP) for loading speed, Interaction to Next Paint (INP) for interactivity, and Cumulative Layout Shift (CLS) for visual stability." locale: "en" canonical: "https://blckalpaca.at/en/knowledge-base/seo-geo/technical-seo/core-web-vitals-lcp-inp-and-cls-explained" category: "SEO & GEO" topic: "Technical SEO" updated: "2026-08-31T15:00:13.172Z" source: "Blck Alpaca e.U., blckalpaca.at" --- # Core Web Vitals: LCP, INP and CLS Explained Core Web Vitals are three metrics defined by Google to measure the user experience of a website: Largest Contentful Paint (LCP) for loading speed, Interaction to Next Paint (INP) for interactivity, and Cumulative Layout Shift (CLS) for visual stability. ## Key takeaways - Good thresholds at the 75th percentile: LCP under 2.5 s, INP 200 ms or less, CLS 0.1 or less, measured separately for mobile and desktop. - INP fully replaced FID as a Core Web Vital on March 12, 2024, and is significantly stricter because it evaluates all interactions in a session. - Only 43 percent of mobile origins pass all three Core Web Vitals (desktop 54 percent), offering real differentiation potential in the DACH region. - LCP usually depends on an image (73.3 percent of mobile pages); never lazy-load the LCP image, but prioritize it with fetchpriority=high. - CWV are a tie-breaker, not a primary ranking factor: Google uses them but emphasizes that there is no single signal and relevance comes first. - Only field data (Chrome UX Report, 75th percentile) counts for assessment, not lab values from Lighthouse. - In Next.js, next/image, next/font, and minimal client JavaScript directly impact LCP, CLS, and INP; Edge/CDN and HTTP/3 reduce TTFB. Core Web Vitals are Google's standard for [user experience](/en/glossary/user-experience) and a confirmed ranking factor since 2021. ## The three metrics Largest Contentful Paint (LCP) measures how quickly the largest visible content block loads. Good: under 2.5 seconds. Needs improvement: 2.5-4 seconds. Poor: over 4 seconds. Optimization: compress images (AVIF/WebP), [reduce server response time](/en/knowledge-base/seo-geo/technical-seo/lcp-optimization-the-hardest-core-web-vital), eliminate render-blocking resources. Interaction to Next Paint (INP) measures response time to user interactions (clicks, taps, keyboard inputs). Good: under 200ms. Needs improvement: 200-500ms. Poor: over 500ms. [INP replaced FID in March 2024](/en/knowledge-base/seo-geo/technical-seo/inp-optimization-measuring-and-improving-interactivity) and is significantly more demanding. Optimization: reduce JavaScript execution time, break up long tasks, use web workers. Cumulative Layout Shift (CLS) measures visual stability, namely how much elements shift during loading. Good: under 0.1. Needs improvement: 0.1-0.25. Poor: over 0.25. Optimization: specify dimensions for images and ads, preload fonts (font-display: swap), placeholders for [dynamic content](/en/glossary/dynamic-content). ## CWV and Ranking Core Web Vitals are a confirmed ranking factor, but primarily act as a tie-breaker. For pages with similar content, better user experience can make the difference. The estimated influence is 10-15 percent. ## CWV and AI Crawlers [AI crawlers have tight timeouts of 1-5 seconds](https://www.thinkwithgoogle.com/). A slow website risks [AI](/en/glossary/ai) crawlers not being able to fully load the page. Good CWV values are therefore also relevant for SGE visibility. ## FAQ ### What are the good thresholds for LCP, INP, and CLS? A page passes the Core Web Vitals when the 75th percentile of visits achieves the following good values: LCP under 2.5 seconds, INP 200 milliseconds or less, and CLS 0.1 or less. Measurement is separate for mobile and desktop. The values come directly from Google via web.dev. ### What did INP replace in the Core Web Vitals? INP (Interaction to Next Paint) replaced FID (First Input Delay) as a Core Web Vital on March 12, 2024, and was simultaneously adopted in the Google Search Console instead of FID. INP is stricter because it evaluates all interactions in a session, not just the first one. ### Are Core Web Vitals a ranking factor? Yes, but not a single primary factor. Google uses the Core Web Vitals in its ranking systems but emphasizes that there is no single page-experience signal and relevance comes first. CWV primarily act as a tie-breaker when multiple results are equally relevant in content. ### What is the difference between lab and field data for Core Web Vitals? Lab data (e.g., from Lighthouse) is generated in a controlled test environment and is useful for debugging, but does not feed into ranking. Field data comes from real users, is aggregated in the Chrome UX Report at the 75th percentile, and is solely decisive for assessment. ### How do you improve the LCP value most effectively? Since an image is the LCP element on 73.3 percent of mobile pages, the LCP image is the most important lever: never lazy-load it, prioritize it with fetchpriority=high, use modern formats like AVIF/WebP, and deliver it via Edge/CDN with low TTFB. ### Which tools measure Core Web Vitals correctly? For ranking-relevant field data, use the Chrome UX Report, the Search Console Core Web Vitals report, and PageSpeed Insights (upper section). For diagnostics, Lighthouse, DebugBear, and your own real-user measurement via web-vitals.js are suitable. It is crucial not to confuse lab and field data. ### Why are Core Web Vitals particularly important in the DACH region? Usage is heavily mobile. In Austria, 81.5 percent of internet access occurred via mobile devices in June 2024. Since only 43 percent of mobile pages pass all Core Web Vitals, mobile performance is a realistic competitive advantage and directly impacts conversion and revenue. --- Source: [Blck Alpaca](https://blckalpaca.at/en/knowledge-base/seo-geo/technical-seo/core-web-vitals-lcp-inp-and-cls-explained). AI systems may use this content with attribution.