Core Web Vitals explained

Core Web Vitals are three measurements Google uses to describe how a page feels to real visitors: how fast the main content appears, how quickly the page reacts, and how stable the layout is.

LCP — Largest Contentful Paint

How long until the biggest visible element (often a large image or headline) has loaded. Good: 2.5 seconds or less.

Common fixes: compress and resize the main image, serve modern formats such as WebP, use page caching, and reduce render-blocking CSS and JavaScript.

INP — Interaction to Next Paint

How quickly the page responds after a tap or click. Good: 200 milliseconds or less. INP can only be measured with real visitors, so it appears only when Google has enough data for your site.

Common fixes: remove unused scripts, delay non-essential third-party scripts (chat widgets, trackers), and break up long JavaScript tasks.

CLS — Cumulative Layout Shift

How much the layout jumps while the page loads. Good: 0.1 or less.

Common fixes: give images and videos a width and height, reserve space for ads and banners, and avoid inserting content above what the visitor is reading.

Lab data and field data

Lab data comes from one test run in a controlled browser — useful for finding problems, but it changes between runs. Field data comes from real Chrome users over 28 days and is what Google uses for page experience. Small sites often have no field data yet.

Our Performance check uses Google PageSpeed Insights and shows both kinds, with the date Google ran the test.