Core Web Vitals are a set of field metrics that measure important aspects of real-world user experience on the web such as loading, interactivity, and visual stability. The assessment is based on three core metrics:
Largest Contentful Paint (LCP): measures loading performance. To provide a good user experience, LCP should occur within 2.5 seconds of when the page first starts loading.
First Input Delay (FID): measures interactivity. To provide a good user experience, pages should have an FID of 100 milliseconds or less.
Cumulative Layout Shift (CLS): measures visual stability. To provide a good user experience, pages should maintain a CLS of 0.1. or less.
To pass the assessment, a page should meet the recommended targets at the 75th percentile for all of the above three metrics.
Google believes that the Core Web Vitals are critical to all web experiences. As a result, it is committed to surfacing these metrics in all of its popular tools. The following section details which tools support the Core Web Vitals.