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Core Web Vitals: LCP, INP and CLS Explained

Lucas Blochberger··Updated 11 June 2026
Definition

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 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, 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 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.

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. A slow website risks AI crawlers not being able to fully load the page. Good CWV values are therefore also relevant for SGE visibility.

Data & Statistics

INP ersetzt FID seit 12. Maerz 2024 als Core Web Vital und wurde gleichzeitig in der Search Console anstelle von FID gefuehrt.

web.dev (Google / Chrome team) (2024)

good-Schwellenwerte (75. Perzentil, segmentiert nach Mobil/Desktop): LCP unter 2,5 s, INP 200 ms oder weniger, CLS 0,1 oder weniger.

web.dev / Google Web Vitals (2024)

Es gibt kein einzelnes Page-Experience-Signal; die Core Web Vitals werden von den Ranking-Systemen genutzt, und eine gute Page Experience kann bei Suchanfragen mit viel hilfreichem Content zum Sucherfolg beitragen.

Google Search Central - Understanding page experience in Google Search results (2025)

43 % der mobilen Origins bestehen alle Core Web Vitals (Desktop 54 %); mit FID waeren es noch 48 % auf Mobil gewesen.

HTTP Archive - Web Almanac 2024, Performance (2024)

Mobil good 2024: 59 % LCP, 74 % INP, 79 % CLS.

HTTP Archive - Web Almanac 2024, Performance (2024)

73,3 % der mobilen Seiten haben ein Bild als LCP-Element; 16 % lazy-laden ihr LCP-Bild (9,5 % via nativem loading=lazy).

HTTP Archive - Web Almanac 2024, Performance (2024)

+7 % Umsatz nach INP-Optimierung bei redBus; INP selbst um 72 % verbessert (u. a. debounced Scroll-Handler, reduzierte Fetches).

web.dev Case Study (Google) - redBus (2023)

54 % von ueber 1,3 Mrd. Requests werden ueber ein CDN ausgeliefert; HTTP/3 ist bei ~30 % der Seiten verfuegbar, aber nur bei 7 bis 9 % der ersten Seitenaufrufe tatsaechlich genutzt.

HTTP Archive - Web Almanac 2024, HTTP (2024)

Googlebot +96 % YoY (Mai 2024 bis Mai 2025) bei ~50 % Crawler-Anteil; GPTBot von 2,2 % auf 7,7 % (+305 % Requests).

Cloudflare Blog - From Googlebot to GPTBot: who's crawling your site in 2025 (2025)

81,5 % der Internetzugriffe in Oesterreich erfolgten im Juni 2024 ueber mobile Endgeraete (31,6 % via mobiles Web, 49,9 % via App).

Statista, Studie 442514 (Quelle: Oesterreichische Webanalyse / OEWA) (2024)

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.

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