Core Web Vitals Checker

Check your website's real-world performance metrics (LCP, CLS, INP) for mobile and desktop based on Google Chrome UX Report (CrUX) data.

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What Are Core Web Vitals?

Core Web Vitals are a set of specific factors that Google considers important in a webpage's overall user experience. They are made up of three specific page speed and user interaction measurements: Largest Contentful Paint (LCP), Interaction to Next Paint (INP), and Cumulative Layout Shift (CLS).

Google uses these metrics as a ranking signal, meaning websites with good Core Web Vitals are more likely to rank higher in search engine results pages (SERPs).

LCP (Loading)

Largest Contentful Paint measures the time it takes for the largest piece of content (like a hero image or text block) to appear on the screen.

Good: ≤ 2.5s

INP (Interactivity)

Interaction to Next Paint replaced FID in March 2024. It measures the overall responsiveness to user interactions (clicks, taps) throughout the page lifecycle.

Good: ≤ 200ms

CLS (Visual Stability)

Cumulative Layout Shift measures unexpected layout shifts that occur as the page loads. It ensures users don't accidentally click the wrong button as elements move.

Good: ≤ 0.1

Frequently Asked Questions

To improve Largest Contentful Paint, optimize your hero images (compress them, use modern formats like WebP), set up a Content Delivery Network (CDN), defer non-critical JavaScript, and utilize server-side rendering or caching.
First Input Delay (FID) only measured the delay of the first interaction. Interaction to Next Paint (INP) is a more comprehensive metric that observes the latency of all interactions a user has with the page, providing a more accurate reflection of real-world responsiveness.
Field Data (from the Chrome UX Report or CrUX) is historical data collected from real users visiting your site. It determines your actual Core Web Vitals score. Lab Data (from Lighthouse) is generated in a controlled environment to help you diagnose and fix performance issues, but it does not directly affect your search rankings.

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