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Marketing has long monitored website performance as a measure of the customer experience. But what's the right test for a website or app? Identifying one test has been a challenge. Google's answer to that challenge is Core Web Vitals.

Core Web Vitals are a new set of performance metrics aimed at improving page load speed. A new Google Search Console report replaces the Speed report as a way to monitor how app and website pages perform based on real world usage data. Google announced the change in May.

On its Chromium blog, Google noted it offers Core Web Vitals “to provide unified guidance for quality signals that, we believe, are essential to delivering a great user experience on the web.”

How Google Core Web Vitals Assess Website Performance

Core Web Vitals introduces three core metrics to note various aspects of the user experience: loading, interactivity and visual stability. The metrics are based on data from the Chrome User Experience Report. The Chrome User Experience Report is a collection of anonymized performance time metrics from actual users visiting your URL. Google calls this field data. The Chrome User Experience Report database gathers technical information about a given URL to determine whether or not the URL is part of a Search Console property and should be examined.

The three Core Web Vitals metrics for scoring site performance quality are:

  1. Largest Contentful Paint (LCP): LCP measures loading performance. It is meant to identify the point in the page loading process when the main page content has likely loaded.
  2. First Input Delay (FID): FID measures interactivity. According to Google it is meant “to quantify the experience users feel when trying to first interact with the page.”
  3. Cumulative Layout Shift (CLS): CLS measures visual stability, the amount that a page unexpectedly shifts during its loading. 

LCP and FID are measured as units of time. LCP is in seconds, while FID is in milliseconds. CLS is measured as a percentage of page visits. The following chart notes what is considered a good threshold for each metric.

google core web vitals2
 

Google provide a range for each metrics on its Chromium blog.

google core web vitals range

The Core Web Vitals report appears under the Enhancement section of the Search Console report. The report shows the number of pages impacted, though the chart displays the daily count, but not specific pages.

google web vitals search console report

To know which pages and elements work, developers would then run the Page Speed Insights test on a desired URL. Page Speed Insights generates a performance score that reflects the quality of the page's performance on different metrics. The aforementioned Largest Contentful Paint, First Input Delay, and Cumulative Layout Shift are combined with other metrics such as Total Blocking Time. The end result is the ability to list actionable suggestions for developers and tech-savvy marketers.

Related Article: How Brands Are Using Google AMP for Email, OptIn '19 

What Does This Mean for Apps, Websites and the Customer Experience?

Longer page load times impacts the customer experience negatively. Bounce rates can increase, indicating that customers are leaving a page before engaging intended conversion activities, like a call now button or a form submission.

The introduction of Code Web Vitals reflects Google’s vision to set a common group of signals to simplify the correction signals developers receive and the tools needed. The end result is saving time in determining what app or website changes must be completed. Saving time and guiding developer workflow is a terrific way to ace the test of delivering great digital customer experiences.