Core Web Vitals explained
Google's Core Web Vitals measure how fast and stable a page feels to real visitors. Here's what each one means and how to improve it.
Last updated · By the XKey team
LCP – Largest Contentful Paint (good: 2.5 s or less)
How long until the biggest thing on screen – usually a hero image or headline – appears. Common fixes: faster hosting or a CDN, compressing and resizing the hero image, not lazy-loading the first image, and removing render-blocking scripts.
INP – Interaction to Next Paint (good: 200 ms or less)
How quickly the page reacts when someone taps or clicks. Common fixes: less JavaScript, removing heavy third-party widgets and splitting long tasks.
CLS – Cumulative Layout Shift (good: 0.1 or less)
How much the page jumps around while loading. Common fixes: giving images and embeds a width and height, reserving space for adverts and banners, and loading fonts carefully.
Lab data vs real-user data
Lab tests (Lighthouse) load your page once on a simulated phone. Real-user data (the Chrome UX Report) comes from actual Chrome visitors over 28 days, and it's what Google uses. XKey's page speed checker shows both.
Frequently asked questions
Where can I find my Core Web Vitals?
In Google Search Console's Core Web Vitals report, in PageSpeed Insights, or in XKey's page speed checker.
What happened to FID?
Interaction to Next Paint (INP) replaced First Input Delay as a Core Web Vital in March 2024.
Why does my site have no real-user data?
The Chrome UX Report only covers pages and sites with enough Chrome visits. Until then, use the lab test as a guide.
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