Search Engine Optimization

Core Web Vitals: Google’s New Ranking Signal

User experience has become increasingly important in today’s crowded digital space.

Now, Google has announced that Core Web Vitals, the new page experience signals, are set to be implemented as a ranking factor in May of 2021.

So what exactly are Core Web Vitals? Read on and we’ll cover the details.

What do you need to know about Core Web Vitals?

The new page experience signals will combine Core Web Vitals with existing search signals like mobile-friendliness, safe-browsing, HTTPS-security, and guidelines for intrusive interstitials (popup forms and other similar content).

Core Web Vitals are designed to measure the following factors:

  • Loading speed
  • Interactivity
  • Visual stability

As Google states on the Webmaster Central Blog:

“Core Web Vitals are a set of real-world, user-centered metrics that quantify key aspects of the user experience. They measure dimensions of web usability such as load time, interactivity, and the stability of content as it loads (so you don’t accidentally tap that button when it shifts under your finger – how annoying!).”

What should you focus on?

Let’s look at the three new factors:

  1. Loading—Largest Contentful Paint (LCP): This metric aims to measure perceived load speed and marks the point at which the page’s main content loads. Sites should strive to achieve at least 2.5 seconds or faster to meet the criteria and be assessed as “good”. If your page’s load speed is over 4 seconds, you should work to improve loading times.

Google’s full documentation can be found here

  1. Interactivity—First Input Delay (FID): FID measures how long it takes for the browser to start processing event handlers in response to visitors interacting with your page. Sites should aim to have this at 100 ms or less. 300 ms or longer is considered poor performance.

What counts as an interaction? Here are some examples:

  • Choosing an option from a menu (clicking on a button or selecting from a drop-down menu)
  • Clicking on a link
  • Entering text into a field
  • Opening up “accordion text” on mobile devices

Here are the things that you can do to improve FID scores.

  • Minimize (or defer) JavaScript: Minimizing or deferring JavaScript on your page is the key to a good FID score.  It will be inconvenient for users to interact with your page while the browser is still loading up the JavaScript.
  • Remove any non-critical third-party scripts: third-party scripts like Google Analytics and heatmaps can negatively impact your page FID score.
  • Implement caching: Using this will help your content and scripts load faster.

See the full documentation here.

  1. Visual Stability—Cumulative Layout Shift (CLS): This is the newest metric, but it’s the easiest to address. It will test the visual stability of your page as it loads. CLS tests the sum total of all the layout shift scores for every unexpected layout shift that occurs during the lifespan of your page.

To make it simple, if the elements and visuals on your page move around as your web page loads, your page will have a high CLS score, which has a negative impact on your overall web vital score.

An ideal measurement is less than 0.1. Note that this metric will not include the expected layout shifts, such as when a page visitor clicks on a link or button that will cause your page to move. 

How to view your own Core Web Vitals

The new metrics can be assessed using the following tools: 

Note that Google will use the field data for ranking signals. FID can only be tested in-field since this metric requires a real user to interact with your web page.

How important are Core Web Vitals for SEO?

A page experience signal is a tie-breaker for multiple pages that provide equally excellent content. The one with the stronger page experience signal will rank higher in search results.

These metrics will help Google make ranking decisions that favor user-friendly, performance-optimized sites. Content will still be the primary focus, but making sure your site’s performance meets these standards can help give you an edge over competitors with similar content.


The introduction of Core Web Vitals as a ranking factor is a step in the right direction, encouraging website owners to further improve their audience’s experience.

By getting an early jump on these changes, you’ll be giving your audience a great first impression of your business and getting ahead of competitors who haven’t given their site the extra attention.

While metrics and ranking factors frequently change, making sure your audience has a great experience should always be your top priority.

Web Vitals is a way for Google to provide unified guidance for quality signals. Learn more about it in this article.

By Zac Almeida

Before joining the team at Ethical Digital, Izaias built a successful SEO agency in São Paolo, Brazil. With over twelve years of experience providing data-driven SEO, he has worked with businesses of all sizes - from SMBs to Fortune 500 companies. After selling his business to travel the world with his wife, "The SEO Hustler" has been helping companies in more than 15 countries and 6 languages thrive in the digital and search world.


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