Introduction
Cumulative Layout Shift (CLS) may be a technical term, but it is actually just how much your page wobbles back and forth during loading. If your page is moving out of place unexpectedly, it is as if your visitors are trying to read a book while someone keeps flipping the pages.
Seems frustrating, right? Yes, it is frustrating for them.
Not only does this make your site feel unstable, but it also hurts your SEO. Because Google doesn’t like shaky sites, just as your users do.
Fixing CLS issues is a must for a better user experience and higher search rankings. But don’t worry, we are here to help. In this guide, we will show you what’s causing those annoying shifts and give you the top tricks to stop them. Oh, and we are throwing in a free tool to make it all super easy and quick.
So, if you agree, then let’s start by thoroughly understanding CLS.
What is the Cumulative Layout Shift?
CLS is a “stability meter” for your website. As we discussed, it measures how much your page wiggles and moves around while it’s loading.
A layout shift happens when something suddenly changes its position or size, and makes the rest of the content shift around like dominoes.
Why should you care? Well, search engines love stable sites. If your CLS score is high (anything over 0.1), it is a big red flag.
A shaky site makes for a terrible user experience, and Google definitely doesn’t want its users to suffer through that.
CLS is part of the Core Web Vitals, a set of important metrics that can impact your ranking on search results. If you are okay with too high scores, then be ready to say goodbye to high rankings.
On the bright side, if you have a fully static page (which is the best scenario), then your score is as low as 0.
Now, let’s see if your website is shaking or is steady, and what you can do to fix it.
How to Measure Your CLS Score?
If your site images, buttons, and iframes unexpectedly shift in front of visitors. They will start seeing your site as unstable or even untrustworthy.
And if people don’t trust your site, they are definitely not pulling out their wallets to purchase what you offer. That is a direct hit to your business.
You can only make it look and feel fast, stable, and professional when you optimize it for CLS.
CLS Standards
| Good | Below 0.1 | You are doing good |
| Average | 0.1-0.25 | Time to fix things |
| Poor | Above 0.25 | Need Urgent Optimization |
If your website’s performance score is not looking great, don’t worry. You are not alone; we are here to support you. But before we jump into how to solve CLS issues, let’s get clear on how to check what is really going on with your site’s layout stability.
There are two main ways to test for Cumulative Layout Shift (CLS):
- With lab testing, you can find and fix problems in a controlled setting.
- Field testing tells you how real users experience your website.
Here is a quick comparison of tools and the kind of data each provides:
| Tool Name | Lab Data | Field Data |
| Lighthouse | ✅ Yes | ❌ No |
| PageSpeed Insights | ✅ Yes | ✅ Yes |
| GTmetrix | ✅ Yes | ❌ No |
| Search Console (Core Web Vitals Report) | ❌ No | ✅ Yes |
| Chrome DevTools | ✅ Yes | ❌ No |
| Chrome User Experience Report (CrUX) | ❌ No | ✅ Yes |
| WebPageTest | ✅ Yes |
❌ No |
Pro Advice: Don’t just stick to one testing method; rather, combine both lab data (simulated conditions) and field data (real user experience) for a full, accurate picture of how your site performs.
Among all these, PageSpeed Insights stands out by offering both lab and field data. So, if you are aiming to fix layout shifts, go to PageSpeed Insights and paste the link of the page you want to test, then click “Analyze”.
Once the results load, scroll down to find Core Web Vitals and under this section, look for Cumulative Layout Shift (CLS).
There, you can see a list of specific elements causing layout shifts. Here’s how you can use that data:
- Check the URLs and elements flagged for shifting.
- Use the “Avoid large layout shifts” section to spot exact issues.
- Look at screenshots and timings to see when and where the shift happens.
You should run the test for multiple pages on your site, especially the home, product, and landing pages, and fix issues.
Now that you know your CLS score, what’s next?
Understanding where your site stands is just the first step. The real challenge is identifying what’s causing these layout shifts and how to fix them effectively in WordPress.
Let’s dive into the most common reasons behind unstable layouts and the exact steps you can take to ensure a smooth, visually stable experience for your visitors.
Common Cumulative Layout Shift Causes
Many site owners don’t realise that their Cumulative Layout Shift (CLS) score can differ across various pages, and even change between desktop and mobile views. That’s right! A page might look fine on your laptop but jump all over the place on a phone screen. And that matters a lot because over 60% of all web traffic now comes from mobile devices.
What’s Causing These Shifts?
Let’s break down the common triggers behind a poor CLS score:
1. Images, Buttons, and Links Without Set Dimensions
When images, buttons, or links are added to a page without giving them a fixed width and height, the browser doesn’t know how much space they will take.
So, it leaves no space for them at first.
Then, when these elements load later, they suddenly push the content below them down, and this sudden shift causes layout instability.
This is a common issue with:
- Product images
- Navigation buttons
- Icons or logos
The shift makes your site feel jumpy, which can confuse or annoy users.
2. Ads, Banners, or Embeds Without Reserved Space
Ads and embedded content (like videos or banners) are often loaded from outside sources, and their size isn’t always known early.
If you don’t reserve space for them in your layout, they appear suddenly, and everything below them will be moved down or aside.
This surprise movement is a major reason for high CLS scores and creates urgency to know how to fix CLS issue.
You will often face this issue with:
- Google Ads
- YouTube videos
- Affiliate banners
- Social media widgets
It ruins the user experience, especially when someone is reading or about to click, and the page suddenly shifts, they end up clicking the wrong thing by mistake.
3. Slow-Loading Web Fonts (FOUT & FOIT)
We all love using stylish web fonts to make our websites look modern and unique. But those pretty fonts can also cause layout shifts if they load slowly.
Why does this happen? Because web fonts are not stored on your computer. The browser has to download them from the internet, and that takes a little time.
During that wait, one of two things can happen:
- FOUT (Flash of Unstyled Text): The browser shows a basic fallback font first, then suddenly replaces it with your custom font when it finishes loading. This changes the size or spacing of the text and pushes things around.
- FOIT (Flash of Invisible Text): The browser hides the text completely until the font loads, then shows everything at once. This creates a delay and often shifts the layout when the text finally appears.
In both cases, the text suddenly moves, which can also affect other nearby content like buttons, menus, or headings. That is why things may jump around unexpectedly and make the layout feel unstable.
4. Messy Animations & Transitions
When you use animation methods like margin, padding, or height to move elements, they physically push or pull other content. This causes layout shifts, the page jumps around while loading or interacting.
Animations look cool, but if you don’t do them the right way, they can break the Optimize layout of your website.
In other words, if they are affecting other content’s position, that means they need to be fixed. But if animation happens in its own space, so nothing else on the page moves. That keeps your layout stable and your CLS score safe.
Yes, so these elements are causing you trouble. But do not worry, as promised, here is the information on how to solve CLS issue with the free WordPress plugin.
How to Fix Cumulative Layout Shift Issues in WordPress?
See first things first, when I am saying there is a tool that can help, so why don’t we just download it? And for that visit this WordPress optimization page, by the free plugin. And install it through the link we sent you over in the mail after completing the checkout process.
Now comes the part of setting it up, and for that, just go to your WordPress admin panel dashboard, then click on add new plugin, and there upload the downloaded W3speedster file.
Step 1: Turn ON “Way to 90+ on PSI” (General Settings)
Once the tool is activated, go to the plugin’s General Settings. Right at the top, you’ll see a highlighted option: “Way to 90+ on PSI”, yes, click on that.
This option isn’t just about scoring high on PageSpeed Insights. It activates multiple pre-built settings that directly improve your overall Core Web Vitals—CLS, LCP, and FID. And since all these metrics are connected, fixing all can often help improve the CLS score.
So turning all the settings in here (including Basic Settings, Optimize images and convert images to webp, Lazyload Resources, Responsive images, css, and Lazyload JavaScript) will be the smart move.
However, if you are unsure, don’t be. Read this dedicated guide on how to improve Google Page Speed Insight score with core web vitals optimization and learn about these settings in detail.
Now, let’s connect everything we discussed earlier about the causes of Cumulative Layout Shift (CLS) to the W3Speedster plugin.
Let’s start with the first issue.
1. Images, Buttons, and Links Without Set Dimensions.
Sometimes, a few images may slip through without proper dimensions.
When you enable the Optimize images and convert images to WebP setting in the plugin, it will automatically detect and set the missing dimensions for you.
Now, let’s look at the second point.
2. Ads, Banners, or Embeds Without Reserved Space.
These types of content often load from external sources and can appear suddenly on your page, causing everything else to shift. But when you enable the Lazy Load Resources setting in W3Speedster, it does more than just delay the loading; it also reserves space for these elements in advance. This means ads and embeds won’t unexpectedly push your content around, and that alone can significantly reduce layout shifts.
Moving on to the third cause.
3. Slow-Loading Web Fonts (FOUT & FOIT).
What W3Speedster does here is it localizes your fonts. Basically, instead of fetching them from the web every time, it stores them locally so they load much faster. It does it only when you turn on the Optimize CSS setting in the plugin. With fonts loading instantly, there’s no shift, and your site remains stable from the start.
Lastly, the fourth issue.
4. Messy Animations & Transitions.
Animations can look great, but if they are not handled correctly, they can cause layout instability. When you enable CSS Optimization and JavaScript Optimization settings in W3Speedster, these animations are cleaned up and optimized to run smoothly without shifting other elements around. So even your visual effects won’t harm your CLS score.
With these features turned on, the plugin fixes the root causes of layout shifts, so your website feels stable, loads faster, and gives your visitors a much smoother experience.
Now we will address the extra Cumulative layout shift optimization setting that you need to make.
Step 2: Preload Fonts:
After localizing your Google Fonts using W3Speedster, you can improve CLS by preloading these fonts.
Go to the W3Speedster plugin menu, then click “Exclusions” → “Resource Exclusions”. In the “Preload Resources” section, add the paths of your font files.
You can find the font paths by inspecting your site in the browser (right-click → Inspect → Network tab). Copy those file paths and paste them in the preload section. This makes the fonts load faster and avoids any visual glitches during page load.
Step 3: Load CSS in the Head to Prevent Final CLS Issues
If you’re still seeing layout shifts, there is one more fix.
In W3Speedster, go to “CSS” settings, and employ “Load Style Tag in Head to Avoid CLS”. Add here the CSS files that are causing layout shifts. You can identify them using the PageSpeed Insights report.
This forces critical styles to load earlier, so your page appears fully styled from the beginning with no sudden jumps.
The above options were designed to help you solve the CLS issue. So, switch them on exactly as directed and see your site working just how you want it to.
Final Words:
Visitors may not know what Cumulative layout shift is, but they absolutely notice when your page flickers or moves unexpectedly.
Studies show that websites with a stable layout tend to have higher engagement and lower bounce rates. That means more people stay longer, interact more, and are more likely to buy, sign up, or return.
Now, you could spend days tweaking code manually, or juggling multiple plugins for fonts, images, JavaScript, and lazy loading, or you could do it all with W3Speedster.
The tool provides the easiest way to fix CLS, boost speed, and improve your Core Web Vitals all in a few clicks.
