Web Vitals is an initiative by Google to provide unified guidance for quality signals that are essential to delivering a great user experience on the web. This metrics represent the best available signals developers have today to measure quality of experience across the web.
Where does data come from?
Web Vitals Leaderboard makes use of Chrome UX Report API that dataset represents how real-world Chrome users experience popular destinations on the web. CRUX aggregates user experience metrics by origin and url, for all websites that are known by Google's web crawlers.
How frequently is data updated?
The data in the Chrome UX Report is a 28-day rolling average of aggregated metrics. This means that the data presented in the Chrome UX Report at any given time is actually data for the past 28 days aggregated together.
How rankings are determined?
Largest Contentful Paint (LCP) measures when a user perceives that the largest content of a page is visible. The metric value for LCP represents the time duration between the user initiating the page load and the page rendering its primary content. Based on real website data, top-performing sites render LCP in about 1,2 sec, so this metric is the most important to represent a fast speed.