Why it matters to a buyer
Core Web Vitals are used by Google's ranking systems, though content relevance matters far more, so they are rarely the reason a page ranks or fails to. Their bigger effect is on people: a slow or jumpy page loses visitors before they read anything, which costs enquiries on every channel. For a buyer the value is that they are objective, published thresholds, so speed work can be scoped and checked rather than argued about.
How it is measured or applied
The thresholds for a good rating are a Largest Contentful Paint of 2.5 seconds or less, an Interaction to Next Paint of 200 milliseconds or less, and a Cumulative Layout Shift of 0.1 or less, each at the 75th percentile. Field data comes from the Chrome User Experience Report and is shown in Search Console's Core Web Vitals report and PageSpeed Insights. Lab tools such as Lighthouse help diagnose causes but do not replace field data. Fixes typically involve image sizing, fewer third-party scripts, server response time and reserving space for elements that load late.
Sources
- Web Vitals, web.dev (Google)
