Name the three main Core Web Vitals metrics.
Name the three main Core Web Vitals metrics.
Ask by Anubhav Sharma
Updated 30 Apr 2025
Core Web Vitals are a set of user-focused performance metrics introduced by Google to help evaluate and improve the user experience of websites. These metrics focus on three key aspects: loading performance, interactivity, and visual stability. The main three Core Web Vitals are Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS).
Largest Contentful Paint (LCP) measures the loading performance of a web page. It specifically tracks how long it takes for the largest content element—such as an image or a large text block—within the viewport to become visible. Ideally, LCP should occur within 2.5 seconds of the page starting to load.
First Input Delay (FID) evaluates interactivity. It measures the time between a user’s first interaction (like clicking a button or link) and when the browser responds to that interaction. This delay is often caused by JavaScript-heavy pages being busy executing scripts. A good FID score is less than 100 milliseconds. Note that with the transition to INP (Interaction to Next Paint) in 2024, FID is being replaced for a more comprehensive interactivity metric.
Cumulative Layout Shift (CLS) assesses visual stability. It quantifies how much unexpected movement occurs on the page while it loads. For instance, if you're about to click a button and the layout suddenly shifts, causing you to click something else, that’s a poor experience. CLS is scored based on the total movement of elements on the page, and a good score is less than 0.1.
Together, these three metrics form a foundation for optimizing website performance and enhancing the overall user experience. Meeting these benchmarks can lead to improved SEO rankings and greater user satisfaction, especially on mobile devices where speed and stability matter most.