Websites, 5 min read
Core Web Vitals in plain English
Three numbers describe how your website feels to a visitor. Here is what they measure and what usually fixes them.
What they are
Core Web Vitals are three measurements Google uses to describe the experience of loading and using a page. They are collected from real visitors using Chrome, and they are one of many signals used in search ranking.
They matter less as an SEO trick and more as an honest description of how your site feels. A page that fails them is a page that frustrates people.
Largest Contentful Paint: how fast it shows up
LCP measures how long it takes for the main content of the page, usually a hero image or headline, to appear. Google considers 2.5 seconds or less to be good.
The usual culprits are oversized images, slow hosting and too much code loading before the content. Compressing and correctly sizing the hero image is often the single biggest win.
Interaction to Next Paint: how fast it responds
INP measures how quickly the page reacts when someone taps, clicks or types. A good score is 200 milliseconds or less. It replaced an older metric, First Input Delay, in March 2024.
Poor INP almost always comes from too much JavaScript: chat widgets, trackers, sliders and plugins all competing for the same processor. The fix is usually removal, not optimization.
Cumulative Layout Shift: how much it jumps around
CLS measures how much the layout moves while the page loads. You have felt it when you go to tap a button and an ad pushes it down at the last moment. A good score is 0.1 or less.
It is fixed by reserving space: giving images and embeds fixed dimensions, and loading fonts in a way that does not reflow the text.
How to check yours
Run your homepage and your most important landing page through PageSpeed Insights, which is free. Look at the field data from real users first, then the lab data. If you have Google Search Console set up, its Core Web Vitals report shows which groups of pages need work.