The Core Web Vitals Report in Site Audit Goes Open Beta

March 2, 2021image


In 2020, Google announced Core Web Vitals – a set of metrics related to speed, responsiveness, and visual stability – to help site owners measure user experience on the web. This new ranking factor is set to be rolled out in May 2021.

Bearing in mind how decisive the upcoming update is going to be, we have released an early version of the new related report in Site Audit so that you can start measuring and improving those metrics right away! 

Find the Core Web Vitals report on the main tool’s page in the Thematic Reports section. 


A Closer Look at the Report 

For now, the following widgets are available: 

  • LCP (Largest Contentful Paint) – the amount of time it takes for a browser to load the largest block of content on your homepage.
  • TBT (Total Blocking Time) – the length of time your homepage is unavailable for data input.
  • CLS (Cumulative Layout Shift) – detects homepage content shifts by combining shifts of all elements upon loading.

The most unique thing about the new report is that it shows real-time changes in metrics. You can make changes, re-audit your site and then see how the improvements affect the metrics before they actually start to affect users and Google detects this data.


Please note that we measure data on our server, so it may vary from data shown by your browser or Google Search Console because of network delays. Such discrepancy is absolutely normal. We also recommend using Google PageSpeed Insights to view users' metrics.

How We Collect Data

We use Google Lighthouse to collect the required data. This allows us to measure metrics the way Google does. Instead of the FIB metric, we use TBT, as it’s impossible to obtain users' metrics in laboratory conditions. 

Check out this article to learn more about how we collect data to measure Core Web Vitals.

While the report is in beta, we collect metrics for the main page only, but more useful features are to come soon! 

At this stage, your feedback is indispensable. Is the report working well for you? How can we improve it? Please leave your comments via the feedback form in the tool interface or drop us a line at 

Check the Core Web Vitals of your siteGo to Site Audit

About Semrush

Semrush is a leading online visibility management SaaS platform that enables businesses globally to run search engine optimization, pay-per-click, content, social media and competitive research campaigns and get measurable results from online marketing. Semrush offers insights and solutions for companies to build, manage, and measure campaigns across various marketing channels. Semrush, with over 94,000 paying customers, is headquartered in Boston and has offices in Philadelphia, Trevose, Austin, Dallas, Amsterdam, Barcelona, Belgrade, Berlin, Limassol, Prague, Warsaw, and Yerevan.