Core Web Vitals are three metrics Google uses to measure the user experience of a page: how quickly it loads, how fast it responds to input and how stable it stays while loading. They are part of the signals Google groups under ”page experience”.
How do Core Web Vitals work?
Google sets a threshold for each metric at which a page counts as ”good”:
- Largest Contentful Paint (LCP): the largest visible element has loaded within 2.5 seconds at most.
- Interaction to Next Paint (INP): the page responds to clicks and input within 200 milliseconds at most. INP replaced the older FID metric in March 2024.
- Cumulative Layout Shift (CLS): content barely shifts while loading, with a score of 0.1 at most.
Measurement is based on data from real visitors using Chrome, not on lab tests. For a page to pass, at least 75 per cent of page views must meet the thresholds.
Why do Core Web Vitals matter?
For rankings, they are one factor among many; good content carries more weight. They still count for revenue: a page that loads slowly or jumps around while you tap loses visitors before they enquire or buy. Online shops on smartphones are hit hardest.
Typical causes are large images, too many scripts, and ad or cookie banners without reserved space. With ongoing SEO management, you monitor the scores continuously so that a new plugin or tracking script does not quietly make them worse.
