Cumulative Layout Shift (CLS) measures the random jumps of elements on a web page as it loads, those visual shifts where text and buttons move unpredictably.
This Core Web Vitals metric quantifies the visual stability of your site. It assesses the frequency and magnitude of unexpected movement of elements on a page during loading.
Google considers a good site to have a CLS below 0.1—below this threshold, your visitors enjoy smooth navigation without elements jumping around. Changes can be caused by dimensionless images, slow-loading fonts, or dynamically added elements.
A poor CLS score directly impacts your conversions: a visitor may accidentally click “Delete” instead of “Buy” because a button moves while loading. This is exactly the kind of frustration Google is trying to eliminate.
How does Cumulative Layout Shift influence SEA and SEO?
Cumulative Layout Shift (CLS) plays a key role in your SEO. How? By directly affecting your visitors’ experience, a major ranking factor for Google. Poor CLS can lead to a decrease in visibility and organic traffic.
Google penalizes sites with high CLS by lowering their position in search results.
For SEA, ads can be affected by lags, reducing the effectiveness of paid clicks. A user experiencing layout jumps? They leave your site. As a result, your bounce rate increases and your ad campaigns suffer.
Improving CLS is therefore recommended to ensure the visual stability of a page, thus improving conversion rate and user satisfaction.
To minimize these shifts, two concrete actions are required: define the precise dimensions of your media and optimize the loading of your fonts.
What are the best practices for optimizing CLS?
Here are 3 practices that concretely optimize your CLS:
- For ads and iframes, provide a static placeholder to avoid layout breaks.
- Dynamic content should be added at the bottom of the page or in response to user interaction, minimizing unexpected movements.
- Prefer CSS transformations over layout changes for animations to reduce CLS impacts.
What tools can effectively measure CLS?
Cumulative Layout Shift (CLS) measurement tools offer additional features to track and correct visual instabilities. Some provide a quick overview by providing a CLS score based on your site’s URL.
They also offer a real-world user perspective through browsing data analysis. For more in-depth analysis, other tools allow for precise visualization of resources causing lag, highlighting frames affected by CLS.
Recording tools capture live page behavior and pinpoint elements responsible for layout shifts.
Some browser extensions report whether the page meets performance criteria, although their use is often limited to the initial load.
Why is CLS crucial for user experience?
Cumulative Layout Shift ( CLS ) strongly influences the user experience by ensuring the visual stability of web pages as they load. An optimized CLS avoids content shifts that can irritate visitors.
For example, lags can cause unwanted clicks if a button moves just before the user interacts with the page. These unexpected movements can turn simple navigation into a real obstacle course.
Keeping your CLS below 0.1 ensures a pleasant navigation experience, which helps keep visitors engaged on your site. A good CLS transforms every visit into a perfectly controlled experience, where every element stays exactly where it should be.
How to reduce the impact of CLS on conversions and clicks?
To mitigate the impact of CLS on conversions and clicks, focus on optimizing visual stability . Use techniques like lazy loading for non-essential assets. This helps prevent unwanted movement related to late-loading elements.
Also, make sure to provide placeholders for dynamic elements, like ads, by setting CSS properties like <head> and <head>. This ensures that space is allocated upfront, minimizing shifts. min-height min-width
To refine your approach, regularly monitor your CLS score with specialized tools. These tools will help you identify problem areas and adjust your strategy to deliver a smooth and engaging user experience.
