Core Web Vitals – What you need to know! - Piranha Digital

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Core Web Vitals – What you need to know!

By piranha

23rd July 2021

History of Google’s Core Web Vitals

Google announced in May 2020 that they would be introducing a set of new metrics related to website speed, responsiveness, and visual stability, to help website owners measure user experience on the web. Google believes that Page Experience will lead to a better Web.

Although Google stated at that point in time, “…there is no immediate need to take action.”, the Search Engine Optimisation (SEO) community was quickly awash with views and opinions as to what the upcoming Search Ranking changes would be and how it would affect website rankings.


What are the Core Web Vitals?

Google has decided to provide an overall view of Page Experience by combining signals from mobile-friendlinesssafe-browsingHTTPS-security, and intrusive interstitial guidelines. Their plan is to continue to evolve this metric over time and make a part of the many ranking signals used to determine which websites are presented to users when they use Google for search queries.

The Core Web Vitals form a sub-set of signals within the Page Experience, specifically covering Loading, Interactivity, and Visual Stability.

  • Loading – Largest Contentful Paint (LCP)
    measures perceived load speed and marks the point in the page load timeline when the page’s main content has likely loaded.
  • Interactivity – First Input Delay (FID)
    measures responsiveness and quantifies the experience users feel when trying to first interact with the page.
  • Visual Stability – Cumulative Layout Shift (CLS)
    measures visual stability and quantifies the amount of unexpected layout shift of visible page content.

The Google team developed the Web Vitals initiative to introduce quality signals that they consider essential to delivering a great user experience on the Web. They want web developers to have a better understanding of how users experience a web page. Although this initiative affects Search Rankings and will have your SEO team figuring out how your search visibility is affected, you will need a web developer to action any improvements to your scores.


What are Good Scores for LCP, FID, and CLS?

Google expects that you should strive to have:

  • Largest Contentful Paint (LCP) of 2.5 seconds or less.
    LCP - Largest Contentful Paint
  • First Input Delay (FID) of 100 milliseconds or less.
    FID - First Input Delay
  • Cumulative Layout Shift (CLS) score of 0.1 or less.
    CLS - Cumulative Layout Shift

Google states that to ensure you’re hitting this target for most of your users, a good threshold to measure is the 75th percentile of page loads, segmented across mobile and desktop devices.


How will Core Web Vitals affect my Website Rankings?


Web Core Vitals is a new Ranking Factor, but it is just one of over 200 signals including Domain Factors, On-Page Factors, Website Factors, Backlink Factors, User Interaction, Brand Signals, Webspam Factors, and others they have not divulged.

Google states: “The lab data is based on a simulated load of a page on a single device and fixed set of network conditions. As a result, the values may differ. Our goal is to make sure that pages work well for the majority of users. By focusing on 75th percentile values for our metrics, this ensures that pages provide a good user experience under the most difficult device and network conditions. Any green score (90+) is considered good.”

Google’s Danny Sullivan (Google’s Search Liaison Officer) in a recent discussion with Search Engine Journal stated that he didn’t know if the impact of Core Web Vitals will be significant or subtle, but he doesn’t expect it will cause significant pain, re-affirming that it is just one ranking factor out of many and that ranking relevant sites is the main goal of the ranking algorithm… Google will still try to return the best content to match the search.

Danny states: “I don’t think freak out but do pay attention to it, do understand that it’s a new thing that you need to keep in mind.”

We also know from previous statements that currently the score is relative. If Google can’t decide which content is more relevant for a user query between you and your competitor’s content then having better Core Web Vitals scores might give your website the rankings boost, (assuming you have similar scores for all the other 200+ ranking signals). The key metric here is, where are your web vital scores compared to your online competitors?


How do I improve & pass the Core Web Vitals assessment?

You can improve LCP by changing the content being displayed towards to top of your web pages. This might include looking at page elements such as images, videos, and other online coding elements.

In order to improve the FID score you will need to reduce the number of network requests being made when loading the website pages and usually includes, but is not limited to, reducing the number of JavaScript (JS) and Cascading Style Sheets (CSS) being requested and the execution time required to process those files.

Finally, the CLS score can be improved by paying attention to size attributes of text, images, and video elements, so that it doesn’t change the page layout or cause it to shift whilst loading.



Google is committed to improving the quality of the Web. We expect that Core Web Vitals will become a more prominent ranking factor as Google’s team evolve the part of the algorithm that assesses Page Experience.

At Piranha Digital we can assess your website for all the known ranking signals and our team of digital marketing specialists and website developers can help improve your Core Web Vitals assessment scores along with other search ranking factors that will help grow your business.

Are you ready to start your project? Get in touch today!



Google Search Central Blog – Evaluating page experience for a better web

Google Search Console Help – Core Web Vitals report

Chromium Blog – Introducing Web Vitals: essential metrics for a healthy site

Google – Largest Contentful Paint (LCP)

Google – First Input Delay (FID)

Google – Cumulative Layout Shift (CLS)


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