Core Web Vitals for SEO: An Overview

There are a great many things that go into designing a webpage that offers a good user experience. How fast the page loads and how easy it is to interact with the page are just a couple. And the list is constantly evolving.

Google defines the core elements of a webpage that enhance user experience as “core web vitals.” Core web vitals will become part of Google’s page experience ranking update in 2021. And there is a strong indication that they will significantly impact SEO and how websites rank in Google.

In this article, No. 6 in our series on the page experience update, I’ll discuss what are core web vitals and how they factor into SEO.

What Are Core Web Vitals?

Core web vitals are a series of signals that help assess the usability of a webpage. These “vital signs” are page quality signals that contribute to a good user experience. And that’s good for SEO.

Core web vitals cover things like page load time, responsiveness, and the visual stability of content. At the time of writing, Google’s current set of core web vitals includes:

  • Largest contentful paint (LCP): LCP measures how fast the largest image or text block renders on the webpage. And Google recommends that it happen within the first 2.5 seconds.
  • First input delay (FID): FID measures load responsiveness. This refers to how quickly a webpage loads and executes so that the user can interact with the page.
  • Cumulative layout shift (CLS): CLS measures unexpected layout shifts on a webpage. One example is when a button or link shifts on the webpage, causing a person to click on something other than what they wanted.

Each of these core web vitals has specific thresholds that must be met, which I’ll go into in more detail in future articles.

Core web vitals thresholds chart from Google.
Image credit: Web Vitals, Google Developers

You can expect the core web vitals to evolve over time, but not without warning. According to Google:

… Core Web Vitals represent the best available signals developers have today to measure quality of experience across the web, but these signals are not perfect and future improvements or additions should be expected. … developers should expect the definitions and thresholds of the Core Web Vitals to be stable, and updates to have prior notice and a predictable, annual cadence.

How Might Core Web Vitals Impact SEO and Rankings?

Core web vitals help ensure the user experience with your site is fast, responsive and smooth. This is already a goal of a good SEO strategy.

  • LCP is one way to measure that webpages load fast. It helps your website visitors have a good user experience and stay on your site.
  • FID plays into another good SEO strategy, to keep visitors on your site.
  • CLS helps ensure that the experience is smooth for your mobile users, a key SEO strategy.

Google has not yet specified what percentage of rankings the new page experience signal will impact. We won’t likely hear exactly how core web vitals play into the overall page experience ranking update, either.

But perhaps a different view will help: If your site is slow, it cannot respond quickly to a voice search request. Will voice search become increasingly important? Of course. So overall speed is vital going forward.

Search Engine Land spoke to a Google rep and reported that Google would not be discussing “how much each factor is weighted,” but that “great content with a poor page experience can still rank highly in Google search.”

What we do know is that a fast site already finds favor in Google’s eyes, and page speed is a ranking factor. The most recent news on this was the “speed update” for mobile that rolled out in 2018.

It’s also suspected that Google’s AI, RankBrain, takes into account how users engage with the search results. RankBrain’s goal is to better interpret search queries and serve the most relevant search results. Specifically, RankBrain may look at the time spent engaging with a webpage when accessed from the search results.

Core web vitals help ensure users are happy and stay on your site. This, in turn, can impact rankings. See an earlier article I wrote on SEO and the user experience.

Get a Jump Start on Core Web Vitals for the ‘Fast Page’ Label

Is your website ready to pass the thresholds for core web vitals? If not, you’re not alone. According to research by Screaming Frog, only 12% of mobile and 13% of desktop results passed the assessment.

It’s likely that Google knows the work that is ahead of website publishers in order to prepare. So Google is enticing people to get a head start.

In August 2020, Google announced that it would test a “fast page” label on Chrome for Android, starting in Chrome 85 Beta.

How can you earn that label for your webpages? Google says that “links to pages that have historically met or exceeded all metrics thresholds for the core web vitals” will get the label.

(While Google says “all” core web vitals, it’s unclear how cumulative layout shift factors into the fast page label. I suspect this will be a minor factor at first, but increasing in importance through 2021.)

Google example of the "fast page" label in SERP.

That means that even though Google said back in May 2020 that “there is no immediate need to take action” as the page experience signal will not hit until sometime in 2021, it’s making core web vitals a little more enticing to get a jump start on.

That’s because sites with a “fast page” label in the results can potentially garner more clicks. This is reminiscent of the “mobile-friendly” labels Google created back in 2014, when it wanted website publishers to start putting mobile users first.

More on Core Web Vitals

As we continue our series on core web vitals, I’ll highlight each of the factors — LCP, FIC and CLS — and include frequently asked questions on how to prepare for the coming page experience update.

Google’s Page Experience Update 2021: A Complete Guide for How to Prepare

You can also read about each Page Experience factor in our series:

  1. What’s the Page Experience Update?
  2. How to Make a Mobile-Friendly Site
  3. Intrusive Interstitials & Why They’re Bad for SEO
  4. Safe Browsing to Protect Your Website, Visitors & Ranking
  5. HTTPS for Users and Ranking
  6. Core Web Vitals Overview
  7. Core Web Vitals: LCP (Largest Contentful Paint)
  8. Core Web Vitals: FID (First Input Delay)
  9. Core Web Vitals: CLS (Cumulative Layout Shift)
Ebook to download on Page Experience preparation.
Click to download this entire series as a printable ebook.

Would you like help analyzing and improving your SEO strategy? Contact us for a free consultation today.

Bruce Clay is founder and president of Bruce Clay, Inc., a global digital marketing firm providing search engine optimization, pay-per-click, social media marketing, SEO-friendly web architecture, and SEO tools and education. Connect with him on LinkedIn and other social networks from Bruce's author page.
Comments (6)
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6 Replies to “Core Web Vitals for SEO: An Overview”

You have shared some very insightful information about the core web vitals. But when I check it in my search console it says that there is not much data yet especially for mobile.

Thanks for covering all the concepts in one blog. We’ll look after these LCP, FID, CLS points in our future projects as it’s vital for 2021. I also forwarded your blog to our department so they can also read & start their work accordingly.

Paula Allen

PSG Grant: We hope the information and all the linked sources provide all you need to improve your website UX. Thanks for reading and letting us know.

After this Google update, It gives priority to websites which have been designed user friendly.

Very informative stuff, so 2021 is going to be an year of web vitals. Let see how it goes!!

Very interesting information in here. I always appreciate industry updates, and will certainly begin implementing changes to adapt to newer standards. I am very curious to see how much of a weighting Google places on this aspect going forward in their ranking methodology.


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