Google’s Core Web Vitals – A Complete Guide To LCP, FID, and CLS

In the tech world, this year has been remarkable in many ways. Search engines have developed and become more competitive than ever before. In May, Google also introduced a new set of measures named “Web Vitals.” These core web vitals are the metrics intended to assist web experts and site owners optimize their websites for a quality user experience.

Adding to its launch of game-changing metrics, Google said that “page experience” will be included as a ranking element. Good UI and user experience have become crucial factors for ranking a website. Regardless of the person’s portfolio, understanding the new endeavor will help uncover the possibilities to strengthen the SEO efforts and enhance the website.

Since the time Google rolled out these web vitals, they have become important ranking factors, and it has become the need of the hour for companies to optimize the website with these criteria. Although page experience is not just about Core Web Vitals, it also integrates search signals such as mobile-friendliness, HTTPS security, invasive interstitial restrictions, and secure surfing.

We have curated this blog to help you understand what these web vitals are, what they consist of, and how to optimize the user experience. We will discuss all the core web vitals, i.e., LCP, FID, and CLS. Learn about them and enjoy fantastic results.

Let’s begin.

What are Core Web Vitals?

Web vitals are the metrics that Google uses to provide constant guidance on the fundamentals of a practical website experience. It is regarded as a positive trend as it helps in delivering the greatest possible experience to the website users. With the introduction of the web vitals, the aim was to simplify the landscape and provide all the quantified scores under one roof.

When it comes to Core Web Vitals, it is just a subset of web vitals applied to every website and every web page. These are the set of specific factors considered crucial for the user experience. While these were initially created for the developers, they were also used by website owners to break down the real-world experience of the users. These web vitals are made up of three different measurements: Largest Contentful Paint, First Input Delay, and Cumulative Layout Shift. Each of these three has its unique viewpoint that influences how people interact and engage with the website. Google specifically asks owners to keep an eye on the score of these metrics and make the improvements wherever required.

Learn About Different Core Web Vitals: LCP, FID, and CLS

Let’s take a quick look at each measure of core web vitals, i.e., LCP, FID, and CLS. These might appear overly technical terms at first, but you will understand them easily when you interpret them and look at their actual meaning. So, without further ado, let’s dive into each of the vital metrics.

S.No.  Core Web Vital Metrics Timing

1 Largest Contentful Pain (LCP) Good: > 2.5 sNeeds Improvement: 2.5 to 4 sPoor: Above 4s 

2 First Input Delay (FID) Good: 0 to 100 msNeeds Improvement: 100 to 300 msPoor: Above 300 ms

3 Cumulative layout shift (CLS) Good: 0 and 0.1Needs Improvement: 0.1 to 0.2Poor: 0.2 to 0.3 

LCP (Largest Contentful Paint)

As the name suggests, LCP is a core web vital measuring tool that calculates the time the most significant element of the website takes to load and show up on the screen. To make it clearer, it won’t measure the time the webpage takes to load completely; it simply looks after the loading time of the largest or most important part of the website.

For instance, you are trying to load a webpage that has some text, heading, subheadings, and a large image. The image will be the largest element and will be considered in LCP. By getting it to load quicker, it will appear on the website much faster and offer a better experience to the users. This means that the lower the LCP, the better it would be for the website. As per the new metrics, the loading time of the largest content taking less than 2.5 seconds is considered “Good.” However, if the loading time is between 2.5 to 4 seconds, the website needs improvement, and if it’s more than that, the website will be believed to offer a poor user experience.

To maintain the best LCP practices, four factors must be taken into consideration. These factors are slow server response time, rendering time on the end-user side, load times for diverse resources, and CSS and JavaScript blocking.

FID (First Input Delay)

The next Core Web Vitals that we will discuss is First Input Delay. It is a metric that measures a website’s time to respond to users’ interactions. The interaction might include clicking on a call-to-action, entering personal information, interacting with the menu, etc. Among the three LCP, FID, and CLS, FID is considered a key performance indicator because the faster the website loads and functions, the more likely it is that a person will stay on the page.

To provide an exceptional user experience to the website visitor, this metric is something one should pay attention to. Generally, when a browser gets multiple requests, it is not supposed to take all of them at once. Instead, it puts certain requests on hold until one gets processed and completed. This, in turn, delays the work. Therefore, it is required to reduce FID timing and offer a better experience to the user. For improving the FID of a website, the following points should be focused on.

  • JavaScript execution time
  • Impact of third-party code
  • Main thread work
  • Request counts and transfer sizes

To better understand and improve the FID of a website, you must learn about its score. Since this metric provides an accurate understanding of user experience, it is crucial to consider the score, and one should try to reduce it to as minimum as possible. A good FID score is when response time is below 100 milliseconds. If timing is between 100 to 300 milliseconds, Google suggests improving the website, and if it is over 300 milliseconds, the FID score is considered poor.

CLS (Cumulative Layout Shift)

The third and last core web vital that we will discuss is CLS, i.e., Cumulative Layout Shift. It is a metric used to measure the website’s stability or how “stable” elements load onto the screen. For instance, when a user tries to click a button after the page has loaded, certain layout adjustments occur because of which the user ends up clicking the wrong button. Since unstable elements offer a bad user experience, the website owner needs to check for CLS and ensure that the page is moderately stable. To check how many times different elements like video, images, copy, audio files, etc., are jumping while loading, the website layouts or content shift is analyzed.

Unlike other metrics of Core Web Vitals, CLS is not measured in seconds. It works in the form of viewpoint size. The unstable elements that move in between the two frames are measured, and their movement is calculated in viewports. Two elements are taken into account to calculate the layout shift score, i.e., “distance fraction” and “impact fraction.” The change in the position of the elements confuses the user and hinders their experience. This is why a CLS score of more than 0.25 is considered poor, and a website with a score between 0.1 and 0.25 needs improvement. At the same time, a score of 0.1 or less is regarded as good.

Different Tools For The Measurement Of Core Web Vitals

Now that you have understood all about Core Web Vitals and its components, it’s time to learn about the tools to test and analyze your website’s score. There are several tools available for monitoring and improving the site’s performance. To help you out, we have listed some of the significant tools.

  • PageSpeed Insights: PageSpeed Insights or PSI tool is a full-service measuring tool that helps in the easy evaluation of metrics of core web vitals. It analyzes the website’s speed performance and serves with multiple audits and suggestions, which helps optimize the website and load it faster. The major advantage of this tool is that it provides insights and detailed reports of both desktop and mobile devices.
  • Lighthouse: This is another Google tool that is highly used for measuring core web vitals. Lighthouse is great for assessing the effectiveness of your page speed, SEO, and for monitoring performance. It is armed with several audits and some SEO checks, making it a potent analysis tool.
  • Search Console: The Google Search Console is another powerful and easy-to-use tool for examining web vitals. Using this tool, one can check the report every time they conduct a website audit. Despite this, what makes it a perfect tool is that instead of displaying the page performance of a single web page, it showcases the result of all the pages at once.

Ways To Fix LCP, FID, and CLS

Once you are done learning about LCP, FID, and CLS, you need to understand how to optimize and fix the issues in each of these core web vitals. Fixing the issues will help a website owner improve user engagement; hence, it must be done correctly.

Although every website is unique, and it is uncommon that two of them suffer from the same issue every time, fixing the core web vitals requires the owner to dig in and analyze the domain individually. However, some common issues are to be fixed in the same manner whenever they get encountered. Here are those standard solutions for each metric.


  • Impose instant loading using the PRPL pattern
  • Optimize your Critical Rendering Path
  • Evaluate image file sizes and compression
  • Manage or remove web fonts and Java scripts


  • Minimize third-party code impacts
  • Reduce the time it takes JavaScript to execute
  • Decrease the number of requests and the size of transfers
  • Cut the time spent on the main thread


  • Encompass size attributes on all the images and video elements
  • Make use of transform animations rather than property animations
  • Add CSS aspect ratio boxes on the website
  • Make sure you won’t place new content over existing content

Future Of Core Web Vitals

As we are done discussing core web vitals, we should also understand what the future holds. Since the digital world is changing rapidly, we will see many changes in the coming years. Other than that, the weight of CLS is likely to be increased, and FID could become stricter than ever. Still, we can conclude that the web vitals will grow with time because of their importance in user experience and easy understanding.

Final Words

These are the three core web vitals that have become metrics to measure your website’s loading, interactivity, and visual stability. Optimizing the user experience with the help of LCP, FID, and CLS metrics is key to the long-term success of a website or business. Trust us, the sooner you learn about each of them, the better it will be for your website.

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