Everything You Need to Know about Google’s Core Web Vitals

Google has recently announced that it would be making significant changes to its algorithm. In May 2021, page experience signals will become a new ranking factor. Specifically, page experience signals include both existing user experience signals and Google’s core web vitals.


By the middle of June, this update could have a major impact on most websites, including yours. Would you like to learn more about these important core web vitals and how you can prepare for the upcoming page experience update? If so, this guide is for you!

Let’s dive deep into everything you need to know about Google’s core web vitals and how you can improve them for your website.

What are Google’s Core Web Vitals?

Core web vitals are a set of vital signals that measure the page experience for all pages of a website. These signals primarily measure page speed, visual stability, and responsiveness from a user’s point of view.

Recently, Google has decided to combine the core web vitals along with the pre-existing user experience signals to get a more holistic overview of the user experience offered by web pages. These page experience metrics are being introduced as a part of the ranking criteria by Google and hence, they will play a major role in determining any website’s rankings.

Currently, there are three core web vitals: Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS). These vitals are used to measure three major aspects of user experience – loading, interactivity, and visual stability, respectively.

These three major core web vitals are being added as page experience signals. In addition, Google intends to make some improvements and add some more vitals to the list.

Why are Core Web Vitals Important?

Google’s core web vitals will be introduced as a part of the pre-existing search signals that measure page experience. These include safe browsing, HTTPS, mobile-friendliness, and intrusive interstitial guidelines.


This means that your website’s core vitals will significantly impact its rankings, and it is important to track them. In addition, working on improving your website’s core web vitals can help you rank higher up on Google’s search engine results page.

Moreover, as Google points out, the core web vitals are focused on creating a holistic, user-centric approach to page experience. Hence, apart from improvements in rankings, enhancing your website’s core web vitals will also help you offer a better user experience, leading to an increased conversion rate and profitability for your business.

Core Web Vital Measurements

Now that we have covered Google’s core web vitals and why they are essential, let’s take a look at three metrics that make up these core web vitals.

Largest Contentful Paint (LCP)

The LCP measures the loading performance of a page. It determines the page load speed as perceived by users as opposed to other page speed measurement metrics. Simply put, the LCP is the time it takes for the user to be able to see the majority of content on their screen after clicking on the link.

Moreover, the LCP takes into account the user’s point of view while loading a page. It also considers the user’s ability to view the majority of the content and interact with the page. The LCP is closely related to the First Contentful Paint (FCP), which is a metric that captures the beginning of a page load instead of taking account of a user’s perspective.

The LCP is measured in seconds, and a good LCP is considered to be of 2.5 seconds or less. In contrast, an LCP score of above 4 seconds is considered to be a poor score that needs improvement.


Furthermore, the LCP also considers the render time of the biggest text or image element visible on the screen. This usually includes text blocks, images, and video elements on a page.

Google considers LCP as a priority, as it gives us a realistic view of the user experience offered by a page. Page elements such as menus and headers are usually the first ones to get loaded. However, these do not constitute the main content of the page which the user is interested in.

Here are a few ways in which you can improve your site’s LCP:

  • Implement lazy loading for your web pages so that all images of your page do not load at once, as this will increase your LCP.
  • Ensure that you compress images before uploading them. Also, try to remove any large elements that will slow down your web page, as removing them can significantly improve your page’s LCP.
  • Implement CSS minification, which will also lead to a better LCP.
  • Remove unnecessary third-party scripts from your web pages, as these may significantly slow them down.
  • Ensure that you invest in a high-speed, good-quality web hosting service provider, as this may also play a major role in improving your LCP score.

First Input Delay (FID)

The FID is another web core vital metric used to measure the load responsiveness of a webpage. Specifically, it measures the time elapsed from the moment the user begins to interact with a page until the browser processes the responses to the interaction.

Essentially, the FID is the time taken by a user to interact with a web page. Examples of such interactions include clicking on a link, filling out a form by entering text into a field, clicking on a menu item, or any other Javascript-powered control.

An FID of less than 100ms is considered good, while anything above 300ms is considered to be a poor FID score.


The FID is an important metric for ranking sites on Google because it takes into account how users interact with any webpage.

Even if a webpage’s FCP and LCP are good, users should also be able to quickly interact with the webpage and take desired actions. When a website has a poor FID score, the user experience of the page is considered suboptimal.

The first impression of any website or webpage is very important for measuring the user experience. In fact, measuring a website’s interactiveness is one of the best ways to evaluate the users’ first impressions of a website.

For a complete content-based page, the FID metric might not be relevant. This is because the users will be only using the page to read through its content.

However, this metric carries more relevance in the case of login pages, landing pages, homepages, or any other web pages that are designed to drive action.

For example, for a login page, the time required for the interaction is a very important factor in measuring its user experience compared to a blog page. If the interaction with a form on a login page is slow, this will create a bad first impression for its users.

While developing the code for web pages, developers may assume that any element they add to the page instantly responds to events. But, for the end-user, this might not be true. In fact, for users, an element may take a long time to respond to a button or link click.

There may be many reasons for input latency, resulting in delayed responses to users. Since this metric directly impacts user experience, it is important to improve your web pages’ FID. This is especially important for pages that have elements such as calls to action and forms that are designed to drive action from the users.

Here are a few ways to improve your website’s FID metric:

  • Remove the unnecessary third-party scripts such as Google Analytics or heatmaps, as these may delay the page’s FID.
  • Users cannot interact with web pages when Javascript is loading in the background. Hence, minifying Javascript will help you improve the FID for your web pages.
  • Using browser caching mechanisms also help, as these will help your pages load faster so users will be able to interact with them faster.

Cumulative Layout Shift (CLS)

The CLS is the third metric that contributes to Google’s core web vitals, and it is used to measure the visual stability of a webpage. It represents the total sum of all the layout shift scores for every unexpected layout shift on a page. In other words, it is a measure of website stability as it loads.

Remember the time when you started reading through a webpage when suddenly, the placement of the content changed? Or worse, the time you clicked on a link, and as the page loaded, another link opened up? These are categorized as unexpected layout shifts.

An unexpected layout shift happens when a visual element on-screen changes from one position to another while loading. This can massively impact user experience, as it is typically perceived as a nuisance. Moreover, it can also lead to losses to the users.

For example, a user may accidentally click on the “Place Order” or “Pay Now” buttons without intending to do so.

There can be multiple unexpected visual layout shifts when a webpage loads. The CLS is considered to be the sum of all these layout shifts. Ideally, a CLS value of under 0.1 is considered good, while anything above 0.25 is considered to be a poor value.


Visual instability that contributes to a high CLS score usually arises when elements on a page are loaded asynchronously or when new elements are added to the page dynamically. This can include any element such as an image, a video, an ad, or a widget.

Having a good CLS score is important as the visual stability of web pages ensures that users do not need to relearn the contents of the pages. Moreover, it prevents accidental clicks on links or ads.

Here are some effective ways to improve the CLS score of your website:

  • Media with dimensions that are unknown to the browser mainly contribute to a negative CLS score. Hence, you can try using set size attributes for images, videos, and other media resources on your website. This way, the browser will know exactly how much space to reserve for these elements while loading the pages.
  • Ads added to unreserved places also contribute to a higher CLS score. This is because such ads can suddenly crop up in the middle of the contents of your page, thus hindering user experience. Therefore, it is important to keep reserved spaces for ads on your website’s pages.
  • Remove any CSS animations that you may have added to your website, as these may also count as unexpected layout shifts.

How Can You Measure Your Website’s Core Web Vitals?

So far, we have discussed the three core web vitals why they are important. To improve these page experience metrics, you should be able to track and measure them.

Here are some ways to measure and track your website’s core web vitals:

PageSpeed Insights

The PageSpeed Insights tool can be one of the best ways to measure the core web vitals of your website. This tool considers both field and lab data – meaning that the measurement is based on both real users going through your website, as well as on tests run by the tool.

PageSpeed Insights assesses your website’s mobile and desktop versions for these page experience metrics. In addition, it also offers useful suggestions that can help you optimize your site’s core web vitals.

Google Search Console

You can view the core web vitals on Google Search Console by expanding the “Experience” option on the left sidebar. Here, you can find an overview of the core web vital scores of the different URLs on your site.

You can also generate a Core Web Vitals report that measures the page experience metrics of your website’s URLs based on real-world usage data.

Web Vitals Extension

Another way to measure a website’s core web vitals is by using the Web Vitals extension. Using this extension, you can measure the performance of your site, as well as of your competitors’ sites, in real-time.


The page experience update will be one of the main Google algorithm updates in 2021, where the three core web vitals will be implemented as page experience signals for ranking websites. The main focus of this update is to implement a user-centric point of view for measuring the user experience of any web page.

What’s more, Google has hinted at improving the current core web vitals and adding a few more to the list. Hence, the importance of these metrics is probably going to increase in the upcoming algorithm updates. Using the tips offered in this guide, you can get a head start on improving the core web vitals of your site.

While these tips offer a good starting point, SEO is an ever-changing landscape, and going it alone may not get you the results you want. To that end, expert SEO optimization services can help a business improve its visibility, increase conversion rates, and attain the level of growth you’re looking for. To learn more, visit us at Growing Search.

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