Mastering Core Web Vitals: How To Improve CLS Score For Better User Experience



The importance of website performance and client happiness has grown significantly in today's dynamic digital environment. The ongoing improvement and development of the World Wide Web have been the primary drivers of this paradigm shift. The Core Web Vitals performance metrics are a new collection of vital performance indicators that have arisen in response to this growing concern and to guarantee a better user experience. These measurements are crucial in determining the online landscape, highlighting how important it is for websites to excel in both functionality and user-centered service.

What Are the Core Web Vitals?

Google created a set of indicators called Core Web Vitals to gauge the effectiveness and usability of websites. These Core Web Vitals in Google rankings concentrate on three essential aspects: visual stability, interactivity, and speed of loading.

Core Web Vitals is comprised of three distinct metrics:

1. Largest Contentful Paint (LCP)

Loading performance is measured. It specifically counts the amount of time it takes for the biggest element on the page to load (such as an image or video).

2. First Input Delay (FID)

Measure of interaction. A website's response time to a user's initial contact, which might involve clicking a button and submitting text in a form, is measured specifically by this metric.

3. Cumulative Layout Shift (CLS)

Visual stability is measured. It evaluates the degree of unexpected layout movement that takes place when a page is loading, specifically. Visitors may find it frustrating if this happens since items on the website shift around as the page continues to load.

When a website achieves the following standards for each one of these measures, Google will consider it to have an excellent user experience:

Why Core Web Vitals Are Important

Because they have a significant impact on how users interact with a website, core web vitals are significant. They determine how quickly an internet page loads, how effortlessly it functions, and how easy it is to use. Websites that perform satisfactorily in regard to Core Web Vitals are more inclined to be found at the top of results for searches since Google uses these metrics as ranking criteria for websites.

In light of the following, core web vitals are important:

1. User Experience

The user experience of an online presence is key in determining whether a person stays with it or leaves. Poor performance, sluggish load times, and links that are broken can annoy users and make for a bad experience. A good user experience is influenced by a website's loading velocity, interaction, and graphical stability; all of these are measured by Core Web Vitals.

2. Rankings on search engines

The meaning of a positive user experience has always been emphasized by Google, and this is also true with Core Web Vitals. Google began incorporating Core Web Vitals as an order element in their search algorithm as of May 2021. A website's accessibility for potential users will increase if it performs well on Core Web Vitals and ranks better in search engine results.

3. Mobile-Friendliness

In today's society, the majority of people use mobile devices to view websites. The functionality of a web page on mobile devices is also taken into account by Core Web Vitals. Websites that score well on Core Web Vitals for mobile users have a greater probability of being listed higher in search results and offer a superior mobile user experience.

4. Increased Conversions

Increased conversions may result from a positive user experience. Users are more inclined to interact with a website, possibly make a purchase, or carry out another desired activity when the site loads swiftly, is simple to use, and offers the data they need.

5. Competitiveness

There are numerous websites on the internet, making competition fierce. A competitive edge exists for websites that do well in Core Web Vitals over ones that don't. They have an increased likelihood of appearing higher in results from searches, giving them more exposure to potential customers and boosting their likelihood of success.

Impact of Cumulative Layout Shift Scores on SEO

Because it has an impact on the functionality and user experience of the website, the cumulative layout shift is an indicator of its popularity on Google. A website that fails to conform to Google's standards may be penalized. It is one of the Core Web Vitals indicators.

A website with a low CLS score is likely to be unreliable, which can prompt users to depart more quickly. So, a crucial part of an effective WordPress SEO checklist is optimizing the website for a high CLS score.

What is a perfect CLS score?

A website with a highly improve CLS score has a significant number of surprise layout changes. A completely static page, on the other hand, can receive a score of zero.

To assist site owners in measuring and raising their CLS scores, Google has established an accepted standard for all Core Web Vitals metrics:

  • Good: A score of less than 0.1 is considered acceptable by Google.
  • Needs improvement: readings between 0.1 and 0.25 show that modifications must be made to lessen unforeseen shifts.
  • Poor: exceeding 0.25 can harm the ranking of your website.

Unique web pages and displays on a website may have different improve CLS score. Mobile user experiences are more significantly impacted by layout changes on mobile displays.

How to Improve the CLS Score for a Better User Experience:

The Improve CLS score is a ranking criteria; thereby, enhancing it can help your site receive more traffic. Here are four strategies to improve CLS score, along with details regarding their impact and degree of difficulty.

1. Establishing Image and Video Size

To avoid unexpected changes, height and width size characteristics are required for all video and image components on a web page. Here's a case study of how to establish your length and width attributes:

<img src="example.jpg" width="400" height="400" alt="Example of an image.">

But in order for browsers to determine how much space they require to show them, adaptive pictures must adhere to the same aspect ratio.

To help browsers effectively deliver responsive images, the attribute specifies a collection of various image sizes with the same aspect ratio. Here is a sample of how the code appears when this attribute is used:

<img width="1000" height="1000" src="example-1000.jpg" srcset="example-1000.jpg 1000w, example-2000.jpg 2000w, example-3000.jpg 3000w" alt="Example of an image.">

The default aspect ratio can also be adjusted by the majority of modern browsers using both the height and width parameters of the image or video. The example that follows shows how to use CSS aspect ratio bars to avoid design shifts:

img { aspect-ratio:attr(width)/attr(height); }

This function follows an image's size while it loads, helping the browser predict different aspect ratios.

2. Banner ads, embeds, and iFrames: Setting Width and Height

a) Banner Ads:

High layout shifts from banner ads pushing viewable content can result in a poor user experience. In order to avoid low CLS scores, advertising networks and publishers who offer dynamic ad sizes ought to reserve a space beforehand.

In order to prevent banner advertising from pushing viewable content, style the part before the ad tag library is loaded. It's crucial to use this technique when an advertisement sits in every row or column of a page in order to prevent design changes even when the advertisement doesn't load.

Utilizing the min-height and min-width CSS values, set the ad height for the slot element:

<div id="ad-slot" style="min-width: 300px; min-height: 250px;"></div>

Additionally, if utilizing various screen widths, use media queries with CSS to indicate various minimums:

@media screen and (max-width: 970px) { #ad-slot { min-height: 250px; } }

To determine the ideal size for the ad spot, use your historical data. Be sure to take into account variable form factors and minute variations in ad sizes.

This method also functions when non-sticky ads are added to a website. Ads that are loaded off-screen won't cause design changes if the necessary space is added.

b) iFrames and embeds:

It is simpler to be uncertain of an embed's size on a page on the internet because they can assume many different shapes. Platforms consequently don't always set aside the necessary room for embeddable gadgets and programs.

An inline frame (iFrame), which also adds external items to a web page, can alter the layout.

Examine the lengths of embeds and iFrames using the resources available to developers in your browser to prevent low CLS rankings. Select the components you wish to look at by clicking on the pointer icon in the developer tools' upper left corner.

The tool will display the element's size once it has been selected.

Include these sizes in the iframes or embeds you use.

3. How to Use Font Display with Custom Fonts

Your website's Improve CLS score can go up when you use a unique font by doing the following:

  • Flashes of Invisible Text (FOIT): while the personal font is loaded, page rendering is going to show invisible text or a blank font.
  • Flashes of Unstyled Text (FOUT): occur when browsers briefly disregard the page layout in order to show a default font while waiting for the custom font to load.

The layout may change significantly when a custom web font is loaded, frequently because it uses more or less space than the standard typeface does. To prevent invisible and unstyled text, utilize font display options such as auto, fallback, block, swap, and optional.

Selecting a system typeface that is comparable to your website's fonts is an additional way to prevent substantial style changes.

@font-face { font-family: 'Pacifico'; src: local('Pacifico Regular'), local('Pacifico-Regular'), url(www.example fonts.woff2), format('woff2'); font-display: swap; }

By including display=swap after the link while using Google-custom web fonts, users can avoid layout shifts.

<link href=",700&display=swap " rel="stylesheet">

If loading custom web fonts, providing a link rel=preload> value to the font file will help to prevent layout shifting.

4. Reviewing Dynamically Injected Content

Content that is dynamic is another cause of an improved CLS score problem. Websites frequently employ dynamic content to persuade visitors to take a particular action. But it frequently moves the content around if a new content element appears at the top and bottom of a page.

Thus, refrain from adding dynamic content on top of already-existing content. Among the methods for reviewing dynamically injected content are:

  • Clients are being invited to take the initiative to make changes; and add an interaction between user elements to start the loading of new content to avoid sudden changes. A read-either-more or refresh button are two instances. To prevent having an influence on CLS, keep layout shifts to no more than 500 milliseconds.
  • Loading dynamic material beyond the user viewport and using an overlay to invite people to view it, like a Scroll Up alert, is another alternative since shifts that occur away do not contribute to CLS.
  • Utilizing a fixed-size container helps keep your layout from moving. Using a carousel is one of the choices; it's also a good substitute when your dynamic content swaps out one element for another. To prevent inadvertent clicks, make sure that all links and controls await the transition.


  • How can I make CLS better, and what is it?

A useful Core Web Vital assessment is cumulative layout shift (CLS). A small CLS ensures that the page is pleasant. It is a crucial, user-centric metric for gauging the stability of the design because it allows for quantifying how frequently users encounter unexpected layout adjustments.

  • The cumulative layout shift is affected by lazy loading, right?

If a user scrolls through a web page while the visual component is still loading, lazy loading can result in design modifications. Lazy loading is necessary to optimize images on a web page, though.

In order to prevent your CLS score from being impacted, remember to mention the size of the lazy-loading images.

  • Does the CLS score only include content located above the fold?

Absolutely no changes to the content above the fold's layout have an impact on your CLS score. To improve overall effectiveness and website speed, all aspects of a web page must be adjusted. This will attract traffic and ranking.


For the purpose of assessing user experience, cumulative design shift quantifies sudden changes inside the user viewing region. Additionally, CLS has a big impact on your SEO because it impacts Google rankings.

A CLS score of less than 0.1 suggests a web page with excellent visual security, whereas a score of more than 0.25 indicates subpar performance. Although you are limited to employing one method, utilizing both will yield greater precision regarding the performance of the website.

When it comes to improving CLS scores, investing in Premium WordPress themes can make a significant difference. These themes are crafted with meticulous attention to detail, ensuring a seamless and visually pleasing user experience. The well-structured code and optimized design elements in Premium WordPress themes contribute to reducing unexpected layout shifts.

By integrating a Premium WordPress theme, you not only enhance user experience but also positively impact your SEO efforts. The smoother, more stable visual presentation provided by these themes can lead to a lower CLS score, signaling excellent visual stability for your web page.

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