Core Web Vitals
Core Web Vitals are three Google metrics for a website’s user experience: loading time of the largest content (LCP), responsiveness to input (INP) and visual stability (CLS).
Largest Contentful Paint (LCP) measures when the largest visible content has loaded — up to 2.5 seconds counts as good. Interaction to Next Paint (INP) measures how quickly the page responds to clicks and input — up to 200 milliseconds is good. Cumulative Layout Shift (CLS) measures how much content shifts while loading — a value up to 0.1 is good.
Google uses Core Web Vitals as one of many ranking factors. More important is their direct effect: slow or jumpy pages lose visitors before they ever enquire.
They are measured with real user data (Search Console, Chrome user data) and in the lab with tools such as Lighthouse.
What to look out for
- Check values in Google Search Console under “Core Web Vitals” and in PageSpeed Insights — separately for mobile and desktop.
- Deliver images in modern formats such as WebP, properly sized and with fixed dimensions.
- Load the most important image above the fold with priority, everything further down lazily.
- Embed fonts, banners and late-loading elements so nothing shifts.
- Review external scripts critically: every tracking or chat script costs responsiveness.
Common mistakes
- Testing only on a fast office computer, not on an average smartphone on a mobile network.
- Uploading huge photos straight from the camera.
- Cookie banners or ad slots push content down after loading.
Frequently asked questions
In Google Search Console in the “Core Web Vitals” report (real user data) and in PageSpeed Insights, which adds a lab measurement with concrete improvement suggestions.
Lab data comes from a single simulated measurement, field data from real visits with different devices and connections. For Google, the real user data counts.