Your ultimate guide to page experience update and core web vitals!

24 min

Google Page Experience Update: What’s Behind It?
What are Core Web Vitals?
How does Google measure Core Web Vitals?
Core Web Vitals 1×1 – You should know these components

Do Core Web Vitals have an impact on SEO?
Why do you need Core Web Vitals SEO optimization?
Conclusion – Page Experience Update and Core Web Vitals

Rarely before has an algorithm change been announced by Google so early. But now it is getting closer: The Page Experience Update and the newly introduced Core Web Vitals. Have you already prepared your website well enough through search engine optimization to avoid being the loser? We will do the check with you!

Google Page Experience Update: What’s behind it?

Google has announced it for quite a long time: The Page Experience Update. It was introduced in June 2021. But what is behind it? The upcoming update rearranges the composition of ranking factors. One consequence of this may be a complete reordering of the search results. Google has a clear goal in mind: user-friendliness is to be improved, usability simplified and security increased. But that is not all. One buzzword comes up particularly frequently in connection with the Page Experience update: performance. Until now, this factor was difficult to measure. However, with the help of the Page Experience Update and the Core Web Vitals it contains, this is set to change.

Important update:

Google has announced that the rollout of the update will be pushed back a bit. Therefore, the Page Experience Update and the introduction of Core Web Vitals are not expected until mid-June, instead of May as announced at the beginning. It also follows that it won’t be completely live until around the end of August.
The reason for the postponement: Google wants to give webmasters a little longer to fine-tune.

What does the ranking factor Page Experience represent?

In detail: The Page Experience update is intended to help better map website performance. Google deals with the problem that the performance of different pages cannot be measured with the existing metrics. Performance is therefore (as of now) not clearly measurable. This makes search engine optimization more difficult. But this is supposed to change with the Page Experience update. The update includes these four already existing signals:

But that’s not all. Originally, these metrics were supplemented by PageSpeed. This is where the Core Web Vitals come into play, making PageSpeed more tangible. The reason for this is that the components of the Web Vitals can be better documented and are easier to track. The metrics defined here are thus intended to make the performance of a website quantifiable.

On the image you can see a blue honeycomb, which represents the sum of the search signals of the Page Experience ranking factor. Various aspects are included in this factor: Mobile Friendly, Safe Browsing, HTTPs and no instrusive interstitials are already existing metrics. New are the Core Web Vitals (marked red here), which consist of LCP, FID and CLS and replace PageSpeed.
Ranking factor Page Experience – This is how it is composed

It is not yet clear what the weighting of the individual components will be. What is certain, however, is that the four “old” key figures will be combined with the Core Web Vitals to form a new ranking factor – the Page Experience. This will therefore be particularly important for future search engine optimizations.

What are Core Web Vitals?

With the help of the Core Web Vitals, Google wants to create uniform quality signals. These are intended to quantify the user experience with a website in order to enable comparability and identify optimization potential. In this way, Google wants to improve the usability of websites on the web. Core Web Vitals, as a component of the page experience, will be a new ranking factor in the future. In plain language, this means: If you have understood the Core Web Vitals and optimized your website for the other areas of the Page Experience, you also have a good chance of better organic rankings.

How does Google measure Core Web Vitals?

To use the Core Web Vitals metrics, Google accesses two different sets of data:

  1. Laboratory data (lab data)
  2. Field data (also called real user monitoring, RUM)

The difference between the two data sets is easily explained. While field data comes from real users and their interactions with websites, lab data is collected under perfect and consistent circumstances. They show how potential visitors might experience and perceive your website. This in turn can lead to different end results depending on the dataset used.

Google’s statement on this is as follows:

„Field data is coming from real users, whereas lab data comes from a quite strong machine with probably good internet from somewhere around the world. So you might not see the same results.“

LABOR DATACollected simulated data from potential users from a controlled environment with predefined circumstances (e.g., user’s device and network settings)– Creation of reproducible results
– Creation of a debugging environment
– Better verification of the effects of optimization measures
– No recording of bottlenecks
– No correlation with business or site KPIs
Target group and their behavior must be understood in order to interpret data correctly
FIELD DATACollected real data from real users’ experiences with real websites– Capture of real actual conditions incl. bottlenecks
– Correlation with business and site KPIs
– Ranking relevant data
– Restricted key figures
– Limited debugging function
Laboratory data vs. field data in overview

The reason why Google uses different data sets is simple: The actual performance can be influenced by parameters such as the end device or the network connection of the website visitor. However, in order to be able to assess the performance of the page as accurately as possible, laboratory data is also used in addition to the field data of real users.

Which tools are suitable for the analysis of Core Web Vitals?

But it’s not necessarily important for you to know how Google collects the data. Instead, you want to know how you can measure the metrics yourself. Google has already done good preparatory work for this in 2020. The in-house tools are mostly prepared for the Page Experience update. For this reason, measurements of the Core Web Vitals are already possible via all popular Google tools. The following overview helps you to find the right tool for the appropriate metric:

In the picture you can see these developer tools from Google:
- PageSpeed Insights
- Chrome UX Report
- Search Console
- Chrome DevTools
- Lighthouse
- Web Vitals Extension

In all tools the new Core Web Vitals metrics are available, but FID cannot be measured in Chrome DevTools nor. inLighthouse.
Overview of Developer Tools for Measuring Core Web Vitals

The tools are also divided into lab tools and field tools. Lighthouse, for example, uses lab data, while the Chrome UX Report is based on field data. PageSpeed Insights, on the other hand, uses both.

Chrome UX Report

Even though the Chrome User Experience Report is not a real tool, but rather a data source, it is important for Core Web Vitals. It shows you what the user experience of real, anonymized Chrome users is like with different websites. Meanwhile, Google has also added Core Web Vitals here, as it is the new benchmark for evaluating user experience. The UX Report uses aggregated data, which you can view via the following tools:

  1. PageSpeed Insights
  2. The public Google BigQuery project
  3. CrUX Dashboard in Google Data Studio

PageSpeed Insights

Until now, you could always test the performance of a website with PageSpeed Insights. The tool distinguishes between performance on mobile and desktop devices and gives you clear optimization recommendations. A blue flag has been added for the Core Web Vitals. This means that tool users can see directly which measured values are important for this.

The image shows a screenshot of the PageSpeed Insights tool. Here you can see all Core Web Vital metrics marked in blue.
Core Web Vitals (marked in blue) in PageSpeed Insights tool

Search Console

The Google Search Console gives you access to field data. With its help, you can access the Core Web Vitals report, for example. This allows you to see how well your pages are doing in terms of performance and identify those that need extra attention.

The image shows a section of the Google Search Console. In the Core Web Vitals section, you can access a report that shows you the status of all metrics.
Example of the Core Web Vitals report in Google Search Console

Chrome DevTools

Chrome DevTools is a whole set of web developer tools. So you can diagnose problems faster. You just want to do a quick check and see how your site is performing? You can do that very quickly with the DevTool Measure. Here you also get a direct insight into the Core Web Vitals, which are marked with a blue flag, just like in PageSpeed Insights.

In the screenshot of the DevTools Measure, you can see that the Core Web Vitals metrics have also been included here (marked in blue). They are marked by Google with a blue flag.
An excerpt from the DevTool Measure with the Core Web Vitals (marked in blue).


Lighthouse helps you improve the quality of your websites. The tool accesses lab data and creates audits for performance, accessibility, progressive web apps, SEO and more. This way, you can identify issues in various areas and improve user experience. Core Web Vitals are also implemented here. This gives you important diagnostic information that you can use to draw conclusions about your site and appropriate optimizations. Lighthouse is also available as a Chrome extension.

Web Vitals Extension

The Chrome extension “Web Vitals” can be downloaded from the Chrome Web Store here. It allows you to detect problems early and evaluates the three Core Web Vitals metrics in real time.

Here is a screenshot of the Core Web Vitals Chrome Extension. In the top right corner of the browser window, it shows you the (critical) values of each Core Web Vitals metric.
The Core Web Vitals extension shows you the values of the Core Web Vitals metrics directly in the upper right corner of your browser window.

Other tools that give you insights into Core Web Vitals metrics include

Of course, there are other tools besides Google tools that you can use to gain insight into Core Web Vitals metrics.


Sistrix has added a new feature to the tool as part of the Page Experience update. You can access the “Core Web Vitals” tab via the Structure area. This then shows you an overview of the various measured values. In addition, it shows you a graphical progression over time for all three Core Web Vitals metrics. The values are divided into three colors according to your performance. These are based on the predefined values from Google (you can find more details in the next section).

On the picture you can find a screenshot of the function "Core Web Vitals" of Sistrix. You can find it in the tab under Structure and then the subcategory "Core Web Vitals" (highlighted in blue). The function shows you the individual metrics clearly. Additionally, you get a graphic for each of them, which shows the historical course of the metrics.
This is how the Core Web Vitals function looks in Sistrix, source: Sistrix

Screaming Frog SEO Spider

Also, the Screaming Frog SEO Spider tool provides you with insights into Core Web Vitals metrics.

Framed in blue, you can see how the Screaming Frog SEO Spider tool plays out the Core Web Vitals metrics for you.
Here you can find the Core Web Vitals metrics in the Screaming Frog SEO Spider tool

Core Web Vitals 1×1 – You should know these components

A closer look at the Core Web Vitals reveals that they are composed of three different components:

  1. Largest Contentful Paint (LCP)
  2. First Input Delay (FID)
  3. Cumulative Layout Shift (CLS)

There is a reason why this metric is split into three parts: On the one hand, it has long been very difficult to measure when and how quickly a page is fully loaded or how it performs. This should now be simplified by splitting it into the above-mentioned areas. On the other hand, it is easier for webmasters to recognize which part of their website needs more attention and should be optimized.

LCP – Largest Contentful Paint (loading time)

When is the main content of the website loaded? This question is addressed by the Largest Contentful Paint (LCP) metric. The value indicates how high the render time of the largest image or text block of the website is.

The LCP (largest contentful paint) score is divided into three ranges:
1. good: 0 to 2.5 seconds loading time
2. in need of optimization: 2.5 to 4 seconds loading time
3. bad: 4 seconds loading time and more

If you want to provide your website visitors with a good user experience, an LCP score of under 2.5 seconds is perfect. This means that users can see the main content of the page within this time. Google recommends keeping at least 75% of all measured LCP values in the green zone. If you achieve this goal on both mobile and desktop, your site has a good LCP score.

What is included in the analysis of the LCP?

Google considers the following to calculate the LCP:

All the above components are included in the size in which they are also displayed to the user. Margins, borders or similar configurations via CSS are disregarded.

What is the difference between FCP and LCP?

FCP, also First Contentful Paint, is the term for the first element the user sees when loading a website. Unlike LCP, however, this can be a loading animation, a placeholder, or something completely uninteresting to the user. The following examples illustrate the difference:

FCP vs. LCP - The differences in loading time, example website Google
FCP vs. LCP – The differences in loading time, example website Google
The image shows different screenshots that show the login area of Instagram under construction. In the first image, only the Instagram logo can be seen. Already in the second image, the header loads, which is the largest content at this point. In the further course, the login field loads in addition to the "Instagram" lettering. The lettering is the largest element here, which is why the LCP is reached as soon as this is loaded (here image 3 of 5).
FCP vs. LCP – The differences in loading time, example Instgram
The image shows different screenshots, which show a website under construction. On the first image only the search bar and the search entered there can be seen. In the further course the heading and text fields are built up. Here the headline is the largest element (marked green). After some time an additional image is built up, which from then on is the largest element of the page. Thus the LCP is reached here (picture 5 of 5).
FCP vs. LCP – The differences in loading time, example website

In all three examples, you see the largest content at the respective time framed in green. This changes in the course of the loading process and does not necessarily always have to be the image of a page (see example 1). Here you can see that all single images are smaller than the text block itself. Thus the images are subordinated to it.

The FCP is therefore already measured when the user can see even a single element on the page. The LCP, in turn, is only reached when the largest element of the page is loaded. The background is as follows: Google assumes that the largest element is also the one that provides the user with the greatest added value.

How can you determine the LCP?

These tools will help you to analyze the LCP:

You can take a closer look at field data for your site using the following tools:

FID – First Input Delay (interactivity)

How long does it take for a user to interact with the website or for the site to respond to the user’s first input? This time span is measured with the help of FID, the “first input delay”. This gives you an idea about the interactivity and responsiveness of your website.

The FID (first input delay) score is divided into three ranges:
1. good: 0 to 100 milliseconds to interactivity.
2. in need of optimization: 100 to 300 milliseconds to interactivity
3. bad: 300 milliseconds or more until interactivity

A good FID score is less than 100 milliseconds. This means that the website does not need more than the aforementioned 0.1 seconds to be ready and responsive for the first user input, both on mobile and desktop. Google sees room for improvement up to 0.3 seconds. However, anything that takes longer will result in a poor user experience. Thus, anything that takes over 100 milliseconds should be optimized.

Why is FID only about the first input?

The first impression is crucial – whether in reality or in virtual life. If there are delays here directly, this affects the user experience with the page. In addition, the first impression is a large part of the overall impression. As a result, many users draw irrefutable conclusions about the quality and reliability of the website.

Another important point is that the biggest interactivity problems often occur when the page is loading. That’s why it’s important to measure how well things are going at this point, and ideally where improvements need to be made. If you improve these first seconds, it will have a big impact on the overall interactivity of your page and put your website visitors in a positive mood.

What is considered the first input?

FID primarily measures input events. These include discrete actions, such as:

Scrolling and zooming are again continuous actions. Therefore, they are not included in the FID metric.

How can you measure your FID value?

Google has also already integrated this metric into some in-house tools. You can get your field data here:

CLS – Cumulative Layout Shift (stability)

Who doesn’t know it: A website loads, you want to click a button and – poof – the complete page content shifts and you press something else in the worst case.

This kind of instability on the page negatively affects usability and user experience and leads to annoyance for your website visitors. To assess how much your page is affected by this type of unexpected shift, there is a metric called Cumulative Layout Shift (CLS). This is used to measure the visual stability of a page. This includes not only button shifts, but also shifts of images, videos, text blocks, etc.

The CLS score is calculated as follows: The affected portion of the website (affected area) is multiplied by the percentage of shift. The resulting percentage value is the CLS.

The CLS (cumulative layout shift) score is divided into three ranges:
1. good: 0 to 10 percent shift.
2. in need of optimization: 10 to 25 percent shift
3. bad: 25 percent shift and more

A good CLS score is achieved with a percentage shift of less than 10%. However, if the content shifts by more than 25% after the page has fully loaded, there is an urgent need for optimization.


Shifts that are triggered by the user himself, so-called expected shifts, are not problematic in principle. Therefore, they do not have a negative effect on your CLS.

Update: New limits for CLS

Google reacted to feedback from webmasters by adjusting the CLS metric – the company now announced this in a statement on the blog. The time of session windows, which are used to measure the shifts, is now limited to five seconds. The time between windows is one second. A session starts whenever a layout shift occurs. It ends when no shift has occurred for a certain time. As a result, the individual layout shifts are grouped together. This is to enable an intuitive merging.

The GIF shows graphically how CLS is measured using the session windows. The individual shifts are grouped into sessions. Between all sessions there is a session gap, i.e. a pause of one second.
Here you can see the individual sessions including the one-second pause (session gap), source: Google

Improve the CLS value – but how?

If you notice unexpected layout shifts, you should take action. Google recommends three specific points that will help improve your CLS score.

  1. Using size attributes or saving space
    If you use size attributes for images and video elements, you make sure that the browser knows how much memory it needs when loading the image/video. Accordingly, much space is then free for it. Alternatively, you can also “reserve” the memory space. This can be done with CSS aspect ratio fields, for example.
  2. Do not overlay content
    Avoid overlays, i.e. inserting content above existing content. This is only useful if you are responding to user interaction.
  3. Movement and animations
  4. If transitions are animated, it feels more fluid and less abrupt to the user. Whenever content moves to its final location naturally, it increases your chances that website visitors won’t find it annoying and won’t have a bad user experience despite a slight “shift”.

How can the CLS be measured?

To find out the CLS value, both field tools and laboratory tools can be used. These are available to you:

Field Tools

Lab Tools

Do Core Web Vitals have an impact on SEO?

The answer to this question is quite clear: Yes! But with a simple yes, the answer is not yet complete – there is more to it. Like all ranking factors, Page Experience has an influence on the positioning in the search results. But it’s not going to be the new non-plus-ultra ranking factor – even though that’s all the buzz in the Google universe right now. Core Web Vitals in combination with existing User Experience signals are important, no question. But they only look at technical aspects of a website. Content and keywords are nevertheless significantly involved in the position on which your page ranks on the SERP. This means that in practice your site can rank well even with poor page experience signals. However, if it is in competition with a similarly relevant website with better page experience values, the latter will receive the higher ranking. This is why Core Web Vitals are essential in search engine optimization. The logic behind this is quite simple: the more ranking signals you can serve well, the better your ranking.

Google’s Gary Illyes posted the following statement about it on Reddit:

“Like any other search engine, Google works hard to provide the highest quality and most relevant results for users’ search queries. CWV has nothing to do with either of those, not even remotely, so it’s highly unlikely that CWV would ever become ‘the primary driver of organic traffic.’ But that doesn’t mean CWV can be ignored.”

Garry Illyes, Webmaster Trends Analyst

Why do you need a Core Web Vitals SEO optimization?

Slow pages, content that shifts or doesn’t respond – these are all issues that drive users crazy, especially on mobile devices. However, since access via mobile has been increasing for years, it is becoming more and more important to optimize websites for this. By 2020, 80% of all internet users were already browsing the web on a mobile device. Core Web Vitals are designed to do just that: They measure the user experience of pages and therefore have a major impact on mobile rankings, at least initially. Before the newly introduced Core Web Vitals, the following signals were relevant for this:

With the Page Experience update, these are now combined with the Core Web Vitals to form a new ranking factor. So, in order to stand out from your competitors, in addition to informative and high-quality content, you should also make sure that the technical aspects are right. In addition, right now is still a good time to carry out optimizations. Current data from the Chrome UX Report shows that only about 22% of all domains reach the recommended Core Web Vitals values.

The image shows a publication of Chrome UX Report. Here, current figures on the Core Web Vital score of websites are shown. Almost 48% have a good LCP score, almost 90% have a good FID score, and about 46% have a good CLS score. In contrast, only just under 22% of all domains have good values in all three metrics.
Only about 22% of all domains achieve good scores on all three Core Web Vitals metrics

The Chrome User Experience Report includes real user data in its analysis, which Google uses to evaluate the page experience. Google refers to different domains as origins.

A new study by Searchmetrics also shows: More than 97% of all websites studied do not achieve satisfactory Core Web Vitals results in German desktop search. In mobile search, it is 85%. All these sites thus risk ranking losses from the introduction of the Core Web Vitals score in June. Two million websites in the top 20 Google search results in Germany, the USA and the UK were analyzed.

Conclusion – Page Experience Update and Core Web Vitals

With the Page Experience update and the introduction of the Core Web Vitals, Google takes another step towards user-centricity. This update makes it clear that the search engine giant wants to cater more to the needs of its users. Thus, it subtly makes webmasters improve their own pages to that effect. This affects pages that already provide value-added content and rank well, as well as pages that have had difficulties ranking so far. Therefore, if you have optimized your site for the three measures of Core Web Vitals (LCP, FID and CLS), this will increase your chance of good rankings in the search results.

FAQs and questions from our community

When will the Core Web Vitals be introduced?

The Page Experience update was originally supposed to be introduced in May 2021. Google already announced this in 2020. In a new statement, however, the group has now scheduled the update for mid-June 2021. From then on, the ranking factor Page Experience will also apply.

Where can I find the Google Core Web Vitals values?

The easiest way to view the Core Web Vitals values of your site is via the Google Search Console. Here you can use the Core Web Vitals Report to gain insight into the performance of your website.

Why are the Core Web Vitals values different for mobile and computer?

Network connections, viewport size, and devices used affect the field data that is collected for a page. As a result, the corresponding values may be different.

Why do tools like Lighthouse and the Chrome User Experience Report show different metric values?

The basis of Core Web Vitals is data from actual user visits. These are always influenced by the users’ environmental conditions and their interactions.
Lighthouse, on the other hand, is a tool that collects lab data. That is, it simulates the process under constant conditions. Thus, at a given point in time, Lighthouse can provide information on what the data looks like for some users and what opportunities for improvement exist. However, this may differ from the data collected based on actual user visits. Hence the difference with the Chrome UX Report.

I use Safari, Firefox, Internet Explorer, … – is Page Experience also a ranking factor in Google Search here?

Yes, because it doesn’t matter which browser you use. Page Experience ranking signals based on Core Web Vitals can be found globally for all browser types.

What tricks will help me achieve the desired Core Web Vitals values?

Image optimizations, cleaned caches, compressed fonts and the use of a CDN (Content Delivery Network) can help you improve the performance of your website and can optimize negative influences of your CMS.

Does the Cookie Consent banner lead to worse CLS metrics?

The Cookie Banner can make your CLS values look worse – but it doesn’t have to. Cumulative Layout Shift measures shifts that are unexpected and thus worsen the user experience. However, a cookie banner is not unexpected. A user visiting a new page should also expect that he/she will be shown a Consent banner to confirm cookie settings.
Nevertheless, when designing the banner, you must make sure that it overlays the content and, at best, covers it instead of moving it.

When sampling users to collect field data for Web Vitals, are users who have already accepted cookies measured, or are only users who have contact with the domain for the first time measured?

The measured field data actually includes both scenarios. In principle, all possible scenarios that an actual user might encounter with the website are mapped.

What’s behind the update for page usability and how important is it compared to other ranking signals?

Google released the following statement: “The Page User Experience update introduces a new signal that our search algorithms use alongside hundreds of other signals to determine the best content to display in response to a query. In doing so, our systems continue to prioritize pages with the best overall information, even though some aspects of the user experience of the page in question may not be optimal. Thus, the user-friendliness of a page does not carry more weight than attractive, relevant content. “

If I publish an AMP and a non-AMP version of a web page, which one will Google link to?

Google continues to use the AMP version for mobile devices here, as it does currently.

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