Core Web Vitals: What are they and how to optimize them?

Google’s goal is and has always been to optimize the quality of user experience. For this reason, Google has long invested time and resources in finding a formula to better understand the user experience on different websites. Some examples of the tools promoted for this purpose are: Pagespeed Insights, Mobile-friendly Test, Lighthouse, AMP, the Chrome UX Report …

Hence the Core Web Vitals, a way to unify metrics and establish the criteria that define a good user experience. These criteria show us a very important key to the long-term success of any site on the web.

Although in today’s article as a specialized seo agency we will get a little more technical, its content is aimed at everyone: whether you are a business owner, marketing manager, or programmer.

What are Core Web Vitals?

Let’s start from the beginning: What are Core Web Vitals?
As we have commented previously, the Core Web Vitals are a recent Google initiative that aims to provide a unified guide to quality signals in order to understand which metrics or actions we must take into account to offer an excellent user experience on our website.

In this way, we can easily identify the UX and WPO problems that our website presents and find the necessary actions to solve them.

Goals of Core Web Vitals

This initiative has three main focuses or objectives:
The first, focus our attention on the user. Until now, we always thought only about time, and for that reason we looked at metrics such as TTFB or HTML loading time. But the truth is that many of these do not indicate a key moment for the user or affect him. For this reason, Google has brought us the CWVs to try to change this focus, and focus it totally on the user experience. For this reason, it is now necessary to base more on questions such as: When does it take to display the contents? When does it take to load the top content of the page? Or how long does it take to be able to use the web? In summary: we went from looking at loading time to looking at the user experience.

The second goal is simplification. As we have already said, over the years we have seen many types of indicators. In this way, the more than 15 indicators have been simplified into 3. In addition, these can not only be used by programmers or layout designers with technical knowledge but by all users in the world of digital marketing.

The third objective is to help us optimize our web pages. Thanks to the tools provided by Google, we can see exactly where we are failing and have control over the measures that we are implementing.

Breaking down the CWVs

Core Web Vitals are made up of 3 elements: LCP, FID and CLS. Each one of them touches an essential aspect of the web that if we are able to optimize it will help us not only to improve our SEO but also to obtain a good user experience. Let’s see them one by one!

FID or First Input Delay

Definition: Time it takes the browser from when an interaction (a click) is made until it is able to process it. Important to keep in mind, it does not measure the time until the item is loaded, but the time it is able to process it.

Its importance: it shows Google the impression that the user gets when they click. This time will vary greatly depending on the item, the browser, and when the click is made.


Good: below 100 milliseconds

Can be improved: between 100 and 300 milliseconds

Bad: above 300 milliseconds

CLS or Cumulative Layout Shift
Definition: Displacement of the content of the initial load that is seen on top. That is to say that from what you see in the first instance when loading until the page is fully loaded, there are the minimum possible changes. This indicator is not about time.

Its importance: It is about avoiding user frustration from clicking on the wrong item. Adding new elements or resizing existing ones does not count, unless their appearance moves the existing ones.


Good: below 0.1

Can be improved: between 0.1 and 0.25

Bad: above 0.25

LCP or Largest Contentfull paint
Definition: Rendering or loading of the largest content item seen at the top of the page. It goes from when the web starts to load until that element is fully loaded. This element can be a video, image, title …

Its importance: because it is a very important moment for the user since it constitutes the moment in which the user can begin to consume the content of the web.


Good: below 2.5 seconds

Can be improved: between 2.5 and 4 seconds

Bad: above 4 seconds

Tips to improve Core Web Vitals

How to carry out the analysis of the Core Web Virtals for your website?
The first step will be to choose a significant page for each group on your website. For example, if we are talking about an online store, it would be the home page, a category page, a subcategory (if there is one) and a product. From here we must run the main Google tools (Page Speed ​​Insights and Lighthouse) in each of them, to be able to see where we are and what points need to be improved.

Finally, and to avoid death scares, it is highly recommended to review the competition, from the same scheme. The ideal would be to be able to make a comparison between your times and errors and those of your competition for each of the categories or groups of pages on your website. In the end we do not have to achieve perfection, but to surpass our competitors.

Other aspects to consider

The FID is not present in any of the tools as it is an element that depends on the real user. Therefore, to optimize it, we recommend that you look at the TBT (total blocking time) since it is an indicator that is very close.

On the other hand, it is important to analyze performing the different tests and comparisons with stable metrics and in a fixed environment. That is, it does not make sense to do a test one day in one browser and another day in another. For this, we recommend carrying out the tests through the tools that Google offers us and doing it in a specific order:

First, in order to analyze the user experience, we can see the data through Google Search Console, Web Vitals Extention and Page Speed ​​Insights. Once the points to change have been identified, we must apply the changes and carry out tests through tools such as Page Speed ​​Insights, Google Lighthouse and Chrome devtools. Google Lighthouse is a very good option since it performs the tests as if it were a Motorola G4 mobile with a low processor and slow connection. To be able to look in other environments we have the option of doing it with Chrome devtools where you can choose the device and the type of connection to configure the environment completely to your liking.

How do Core Web Vitals affect SEO?

Although today the Core Web Vitals are still NOT a positioning factor and do not affect SEO directly, at this time Google has already announced that they will be included in its algorithm in the near future.

The latest news suggests that these will be included in mid-2021 (Google will notify 6 months before). As you can see, there is little room for maneuver and that is why many people are already working on it.

So, how can CWV affect the positioning of my website?
When they are included, we can find two possible scenarios:

That they take part as one more factor of ranking. In this case, the CWVs will be one more element that will help you position your website better or worse.
Penalty Element. Having bad results in the different elements of CWV can make Google penalize you and make your positions worse.
Either way, CWVs will play a very important role in our positioning, and we expect many changes in visibility and variations in SERPs when they are included.

Conclusion on CWV

Core Web Vitals are based on user experience and not just loading time.
The Core Web Vitals have been created with the goal of simplifying and helping to quantify the experience of our site and identify opportunities for improvement.
They are based on 3 elements: LCP, FID and CLS.
Always carry out our tests with the help of tools that allow us to fix the elements of the environment.
CWVs do not yet directly affect the positioning of our website, but they will be able to do so from 2021.

Do you want to improve your Core Web Vitals metrics? In our seo agency in Barcelona we are specialists in helping all types of companies to sell online. All our websites are designed to comply with Google’s guidelines on speed and user experience. If you need a hand with optimizing your website or improving its speed and positioning, do not hesitate to contact us. We will be happy to help you sell more!

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