Core Web Vitals in Plain English
A website can be described as fast without saying much about the experience being measured. Core Web Vitals make the discussion more specific: Google's guidance gives separate measurements and recommended targets for different aspects of web performance.
Loading: LCP
Largest Contentful Paint, usually shortened to LCP, measures loading performance. In its Web Vitals guidance, Google recommends that LCP occur within 2.5 seconds of the page starting to load to provide a good user experience.
Interaction: INP
Interaction to Next Paint (INP) measures interactivity, the part of performance concerned with responding to interaction. Google's recommendation for a good user experience is an INP of 200 milliseconds or less.
Google's announcement about the interactivity metric confirms that INP is a stable Core Web Vital and has replaced First Input Delay, or FID.
Layout movement: CLS
Cumulative Layout Shift (CLS) measures visual stability. Google recommends a CLS of 0.1 or less for a good user experience.
What a good result means
Google recommends assessing the 75th percentile of page loads, with results segmented across mobile and desktop devices. These targets are intended to assess a good experience for most users. Core Web Vitals scoring is based on performance in the field.
The metrics that make up Core Web Vitals can evolve over time, according to web.dev.
Mobile and desktop results
The Web Almanac's 2025 performance report based its primary analysis on measurements from July 2025, spanning millions of websites and a large volume of page loads. It reported good mobile INP on 77% of websites, up from 74% in 2024, a gain of three percentage points. Desktop performance reached 97%.
HTTP Archive collects Chrome-based page-load data through WebPageTest, measuring behaviour under controlled conditions. The Chrome UX Report, also called CrUX, reflects real-world experiences collected from Chrome users.