Are you a developer or SEO professional looking to understand Cumulative Layout Shift (CLS) better?
With a good CLS score of 0.1 or less, it’s crucial to know where your site stands.
Discover the challenges faced on different devices and connection speeds, as well as the methods for measuring and improving CLS.
Get ready to optimize your website for better performance and user satisfaction.
The Importance of CLS in SEO and Web Development
You should prioritize improving the Cumulative Layout Shift (CLS) on your website because it is a crucial factor for SEO and web development. The importance of CLS in SEO and user experience cannot be overstated.
To optimize CLS, web developers should follow best practices such as reserving space for images, videos, and iframes to prevent layout shifts, optimizing fonts to avoid delays, and using animations that don’t trigger layout changes. It’s also essential to implement CLS optimization techniques for mobile devices, as CLS scores are similar on both desktop and mobile.
To measure and analyze CLS, you can use tools like Pagespeed Insights, which provide both field and lab data for comprehensive evaluation.
Prioritizing CLS optimization will improve your website’s performance and enhance user satisfaction.
Understanding CLS Scores and Their Significance
A good CLS score is considered to be less than or equal to 0.1.
When it comes to measuring CLS, there are two techniques: field data and lab data.
Lab data, on the other hand, is based on tests conducted under controlled conditions for repeatability.
CLS scores can vary between field and lab data, with field data often reflecting the real-world user experience.
Improving CLS is crucial for SEO, as it directly impacts user experience and website rankings.
However, CLS improvement strategies can be challenging, especially on slower connections.
To tackle this, one must reserve space for images, videos, and iframes, optimize fonts, and use animations that don’t trigger layout shifts.
CLS Challenges on Different Devices and Connection Speeds
CLS scores can be affected by different devices and connection speeds, posing challenges for website optimization. The impact of CLS on user experience and search engine rankings cannot be ignored.
Various performance factors contribute to CLS, including image and video loading, font rendering, and dynamic content. To optimize CLS, you can reserve space for elements like images and videos to prevent layout shifts. Optimizing fonts can also help avoid delays and changes that cause shifts. Using animations that don’t trigger layout changes, such as transform animations, can improve CLS as well.
It’s crucial to ensure that your pages are eligible for the back/forward cache to minimize layout shifts. By implementing these CLS optimization techniques, you can improve the user experience and enhance your website’s performance.
Measurement methods like field data from the Chrome User Experience Report (CrUX) and lab data from tools like PageSpeed Insights can help you track your CLS progress and make informed optimization decisions.
Measuring CLS: Field Data Vs Lab Data
To measure CLS accurately, it is important to understand the differences between field data and lab data. Here’s what you need to know:
- Field data: This data comes from the Chrome User Experience Report (CrUX) and is what Google uses for Core Web Vitals. It provides real-world performance metrics from actual users.
- Lab data: This data is based on tests with controlled conditions for repeatability. Tools like Google Lighthouse are commonly used to measure CLS in lab settings.
- CrUX vs Lighthouse: CrUX provides a broader view of CLS across the entire site, while Lighthouse focuses on page-level data. CrUX data can be accessed in Google Search Console, while Lighthouse data is available through tools like Pagespeed Insights.
- Choosing the right tool: The best tool to measure CLS depends on the type of data and the number of URLs you want to analyze. Pagespeed Insights is a good choice for page-level field data and running lab tests, while the Pagespeed Insights API provides lab and field data at scale for verified sites.
Understanding the differences between field data and lab data is crucial for accurate CLS measurement. Choose the right tool and gather the data you need to improve your CLS scores.
Tools and Methods for Measuring CLS
Choose the most suitable tool to measure CLS based on your data type and the number of URLs you want to analyze.
When it comes to measuring CLS, you have two options: field data and lab data.
Field data is obtained from the Chrome User Experience Report (CrUX) and is what Google uses for Core Web Vitals.
On the other hand, lab data is based on tests conducted under controlled conditions for repeatability.
If you want to analyze a single URL or a few URLs, Pagespeed Insights is a great tool as it pulls page-level field data and runs lab tests using Google Lighthouse.
For large websites or multiple URLs, the PageSpeed Insights API, available with an Ahrefs Webmaster Tools (AWT) account, provides lab and field data at scale.
Techniques for Improving CLS on Websites
When improving your website’s layout stability, it’s important to reserve space for images, videos, and iframes to prevent unexpected shifts. Here are four techniques to help you improve your website’s CLS:
- Preventing layout shifts: By reserving space for visual elements, you can ensure that there are no sudden jumps or shifts in your layout, providing a smoother user experience.
- Optimizing fonts: Delayed or changing fonts can cause layout shifts. Optimize your fonts to avoid any delays or changes that may disrupt the stability of your layout.
- Animation techniques: Use animation techniques that don’t trigger layout changes, such as transform animations. This way, you can add dynamic elements to your website without affecting the stability of your layout.
- Back/forward cache: Ensure that your pages are eligible for the back/forward cache (bfcache). This allows your pages to be stored and quickly retrieved, reducing the chances of layout shifts when users navigate back and forth.
Strategies for Optimizing CLS in Web Development
Implementing techniques such as reserving space, optimizing fonts, using appropriate animations, and ensuring eligibility for the back/forward cache can greatly enhance the stability of your website’s layout.
CLS optimization techniques play a crucial role in preventing layout shifts, which can negatively impact user experience and SEO rankings.
By reserving space for images, videos, and iframes, you can prevent sudden shifts that disrupt the visual flow.
Font optimization is another key aspect, as delays or changes in font loading can lead to layout shifts.
Using animation strategies that don’t trigger layout changes, such as transform animations, can further improve the stability of your website.
Lastly, ensuring your pages are eligible for the back/forward cache (bfcache) allows for faster navigation and reduces the likelihood of layout shifts.
Analyzing CLS Across Multiple URLs or an Entire Site
To analyze CLS across multiple URLs or your entire site, you can use tools like PageSpeed Insights API, which provides lab and field data at scale for verified sites with an Ahrefs Webmaster Tools (AWT) account. Here’s how you can make the most of it:
- Analyzing CLS trends: By examining CLS scores over time, you can identify patterns and understand how your site’s layout stability has evolved.
- CLS benchmarks: Compare your CLS scores with industry benchmarks to gauge your performance and see if there’s room for improvement.
- CLS performance comparison: Assess the CLS performance of different pages on your site to pinpoint specific areas that need optimization.
- CLS optimization strategies: Utilize the insights gained from analyzing CLS to implement effective optimization strategies, such as reserving space for visual elements and optimizing fonts, animations, and caching.
In conclusion, understanding Cumulative Layout Shift (CLS) is crucial for both SEO and web development.
With a good CLS score of less than or equal to 0.1, it is evident that many sites have successfully optimized their layouts.
However, challenges still exist, especially on slower connections.
Measuring CLS can be done using field data or lab data, with various tools and methods available.
By implementing techniques such as reserving space and optimizing fonts, developers can improve CLS and enhance website performance.
Analyzing CLS across multiple URLs or an entire site allows for comprehensive optimization.
Overall, prioritizing CLS is essential for achieving optimal user experience and search engine rankings.