Performance
Core Web Vitals in plain English
Three numbers Google uses to judge how a page feels. Here is what each one measures and the usual fix.
Mohd Aibad · · 5 min read
Core Web Vitals are Google’s way of putting numbers on how a page feels to a real visitor. There are three, and each maps to something you can notice yourself.
Largest Contentful Paint (LCP)
How long it takes for the biggest thing above the fold, usually a hero image or headline, to appear. Slow LCP is most often an oversized image, a slow server response, or fonts and scripts blocking the page.
Interaction to Next Paint (INP)
How quickly the page responds after someone taps or clicks. Heavy JavaScript running on the main thread is the usual culprit, so ship less of it and defer what is not needed on first load.
Cumulative Layout Shift (CLS)
How much the page jumps around while loading. Set width and height on images and embeds, and reserve space for banners and ads so nothing pushes content down.
- Measure with PageSpeed Insights and the field data in Search Console.
- Fix the worst template first, not every page.
- Re-test on a mid-range phone, not just your laptop.