Core Web Vitals are three metrics Google uses to assess the user experience of a page. They look at real visitors: how quickly the main content appears, how quickly the page responds and whether the layout stays put while it loads. Google writes that its ranking systems use these metrics.
The three metrics
| Metric | What it measures | Good according to Google |
|---|---|---|
| Largest Contentful Paint (LCP) | Loading: when the largest visible element appears | Within 2.5 seconds |
| Interaction to Next Paint (INP) | Responsiveness: how quickly the page reacts to clicks, taps and typing | Under 200 milliseconds |
| Cumulative Layout Shift (CLS) | Stability: how much the layout shifts | Under 0.1 |
Example
Say the text on a product page appears first, then a large banner loads at the top and pushes everything down. A visitor who was just about to tap “Add to basket” taps the wrong thing. That shows up as a high CLS. Reserving space for the banner solves it.
Common mistake
Treating one measurement in your own browser as the verdict. Core Web Vitals reflect the experience of real visitors, on different devices and connections. A good score is also no guarantee of a higher position; Google describes it as one of the things its systems reward.
How do you check it?
The Core Web Vitals report in Google Search Console shows how your pages perform for real visitors. More technical points are in the technical SEO checklist.