Core Web Vitals scores improving, but nearly 50% of websites still fail on at least one metric

Core Web Vitals are 3 metrics that measure the speed, interactivity and visual stability of a web page. They are a component of Google's "page experience ranking" signals and thus contribute to Google's rating of the overall user experience of your page, and ultimately to its ranking.

The June 2024 Chrome UX Report shows improved website performance on all metrics: LCP, CLS and INP, with "good" scores and improvements as follows:

• Largest Contentful Paint: 63.4% (+2.0%)
• Cumulative Layout Shift: 77.8% (+0.5%)
• Interaction to Next Paint: 84.1% (+1.1%)
• All metrics: 51.0% (+2.3%)

Here is what Google considers to be "good" CWV scores:

• Largest Contentful Paint (LCP): Measures loading performance. To provide a good user experience, strive to have LCP occur within the first 2.5 seconds of the page starting to load.
• Interaction To Next Paint (INP): Measures responsiveness. To provide a good user experience, strive to have an INP of less than 200 milliseconds.
• Cumulative Layout Shift (CLS): Measures visual stability. To provide a good user experience, strive to have a CLS score of less than 0.1.

Recent changes to how INP is measured likely contributed to improved scores on that attribute, and on CWV overall:

• Keypress entries are now assigned an interactionID.
• Under composition, interactionID is now exposed to keydown and keyup events as well as input events.
• InteractionIDs for keydown events are now generated upfront vs. on keyup.
• Added concept of alternative end point for duration management with synchronous javascript modal dialogs.

You can check your understanding of CWV by taking Google's little quiz here:

developers.google.com/lear...zzes/web-vitals/web-vitals