Patrick Cantellow

User experience is officially the next big thing in SEO – a guide to Google’s new UX search signals

Yes, I know, user experience (UX) has always been important for SEOs with long-term strategies. The easier it is for visitors to our websites to find what they need, the longer they stick around with the increased likelihood they convert on our goals.

However, for me, user experience has always felt like the dark horse of SEO, with all-rounders thinking about A/B testing, menu design and the like, creatives thinking about making sure everything looks visually appealing, and those technical SEOs who leave it to the creatives. 

Are we all about to become experts in interactivity, interaction cost, intrusiveness, content stability and Google’s ‘Core Web Vitals’? I hope so.

Table of Contents

Listen to this article:

Why now?

On 23 May 2020, Google announced significant changes to the ranking signals that powers search. The new signals will incorporate the also recently announced ‘Core Web Vitals‘ along with more familiar signals such as mobile-friendliness and safe browsing.

Given Google’s search team is producing a high level of communication on the changes, we know it’s going to be quite important.

Whilst Google’s announcement is inherently very technical thanks to the world of web design, hopefully, this triggers businesses of all sizes to stop getting away with poor user experience and realise that UX needs investment, time, and patience.

Before we get started in the detail, Google has mentioned that they know site owners are focused on responding to the effects of COVID-19, and we will get at least six months’ notice before the changes will be rolled out next year.

The new page experience search signals

Google has always had a focus on user experience in its search signals, including mobile-friendliness, safe-browsing, HTTPS and intrusive interstitial guidelines. The latter, implemented in January 2017, gave us more of an insight that Google was thinking more about guiding the hand of website owners to make the web easy to use for all.

Google’s announcement welcomes three more signals to form what is becoming quite the package of metrics.

Loading or Largest Contentful Paint (LCP)

The metrics for loading and interactivity will be familiar to SEOs who use Google’s Lighthouse tools to achieve PageSpeed maximus.

The Largest Contentful Paint metric measures the perceived load speed of a page in seconds, it marks the point where the main content has already loaded on the page.

What is a good LCP score?
Google recommends that the Largest Contentful Paint should occur in the first 2.5 seconds of the page starting to load.

LCP Score Graphic

Webmasters who already know the importance of this metric often employ a skeleton screen, content placeholders or a blanked-out wireframe design, popularised by Facebook, LinkedIn and YouTube amongst others, to make the period up until the LCP feel less slow.

YouTube loading wireframe
YouTube's loading screen
LinkedIn loading wireframe
LinkedIn's loading screen

To calculate the LCP, your browser will detect the largest element of your web page, that could be an image, a contact form, text, for example.

LCP can be measured in the lab (during development) and in the field (once live). I list some of those tools below.

Interactivity or First Input Delay (FID)

The First Input Delay metric quantifies the user’s first impression of your site’s interactivity and responsiveness.

How soon can a user click, tap a button, or use another interactive element on your website? Can this be done within 100 milliseconds of the LCP completing?

What is a good FID score?
Google recommends to have a First Input Delay of less than 100 millieseconds.

The FID only focuses on responsiveness and clicks, so scrolling and zooming do not count. In addition, not all users to your website will interact with it, so some users will have no FID values, some will have low FID values, and some users will have high FID values. As a result of this, you cannot measure the FID score whilst your website is in development.

Google PageSpeed users will be familiar with the Total Blocking Time (TBT) metric, which correlates well with FID in real-world use. Optimisations you make to improve the TBT should in theory improve the FID.

Visual Stability or Cumulative Layout Shift (CLS)

The last in the three new metrics is Cumulative Layout Shift (CLS).

You know when you are about to click a button, but suddenly the screen moves, and you hit the wrong thing? That is what this metric aims to tackle.

Google actually provides the best illustration of this:

These sudden shifts in page content are a result of content still loading, such as an unoptimized image file, or an element triggered after a certain time, such as a special offer, added to the page above the content you are interacting with

What is a good CLS score?
Google recommends a CLS score of less than 0.1.

Apologies, this next bit gets a bit complicated with even more abbreviations.

The CLS is calculated as:
CLS = impact fraction * distance fraction

The impact fraction is how much an element moves when its unstable. If you have an image that takes up 40% of the user’s screen, but it suddenly moves down 25%, the image has taken up 75% of the screen in total.

The distance fraction measures how much it moved. In this case, 25%.

So we calculate the CLS as 0.75 * 0.25 = 0.1875 (we want to aim for 0.1 or below).

Percentages are used as every screen size is different, so no matter what device the CLS is relative.

There are some cases where the calculation isn’t so simple if content is pushed on screen, and if content was already hiding in the background ready to show. Google’s team cover that here.

To exclude intentional movements, such as tapping on an accordion FAQ implementation, a dynamic form or search box, any layout shifts that occur within 500 milliseconds of a user input are excluded from calculations.

The existing search signals

As mentioned earlier, LCP, FID and CLS join the following explicit signals:

  • Mobile-friendly – Google is ‘mobile first’, which means they consider the mobile version of your website before the desktop one. A poorly mobile optimised website, such as small text, touch elements too close together or blocked files are serious problems for users.
  • Safe browsing – your website should not contain any malicious content, files or have any active security issues.
  • HTTPS – what has become known as the green padlock. HTTPS is an important ranking factor so make sure you have an SSL certificate.
  • No intrusive interstitials – pop-ups. Pop-ups that cover the content of your page immediately after loading, whilst scrolling or requires dismissal before accessing the content are poor user experience signals for Google.

These are the explicit signals that Google lets us know about, however, we know there are thousands, potentially millions, of other signals that Google considers when crawling your website. From more basic optimisations in metadata to keyword density, bounce rate and rendering.


Technical SEOs and webmasters will be familiar with some of the tools mentioned below.

Core Web VitalIn the lab (during development)In the field
Largest Contentful Paint (LCP)
First Input Delay (FID)

Whilst you cannot directly measure FID in development, you can use Total Blocking Time (TBT) as a comparable alternative. Generally, optimisations here improve the FID.

Total Blocking Time lab tools:

Cumulative Layout Shift (CLS)

Measured your website using the tools above?

How did you score? Get in touch if you need advice and support to get your website optimised for the core Web Vitals.

Who is going to be the big winners?

The big winners are brands who combine technical UX (everything above) and verbatim UX comments (actively asking users for feedback) together to create an ongoing plan of attack to make their website work for their users.

Developers who keep organised code will also find themselves at an advantage with agility and understanding of how their website works to find resolutions to the flags that the tools above raise.

Those who consider user accessibility beyond the de-facto will also find themselves being rewarded with happy users. For a long time, our industry has largely neglected users with accessibility requirements. Fast-growing tools such as accessiBe are set to change that, making it easy for all users to change everything from text size alignment and contrast to navigation adjustments.

A shoutout to Stablepoint, who I use for my own hosting, for implementing this on their website which is where I first saw it.

Final thoughts

I don’t think is the last time we will hear from Google on Core Web Vitals and UX-influenced ranking signals in 2020 and 2021. As mentioned earlier, the behemoth that is Google, dominating search and browser technology, will likely take further steps to control the web.

I’m looking forward to connecting more with UX designers and hearing from users on what they want.

Over the next few weeks, I will be researching the biggest brands, and some smaller ones too, in multiple different industries and see who is already performing well, and who still has work to do.

Share this article

Share on facebook
Share on twitter
Share on linkedin
Share on reddit
Share on whatsapp
Share on email

Related articles