Core Web Vitals is rapidly becoming a necessary practice for websites. But what is it, and how do we approach it?

Staying updated with the changes in SEO technologies can be challenging, even for the more experienced specialists. The race to outrank your competitor is decided on a series of optimisations that can establish who has the edge and, ultimately, who can attract more, better-qualified visitors to their website.

In the ever-changing landscape of new protocols in the field of SEO, Core Web Vitals is presenting itself as one of the more promising leading criteria in Google’s ranking systems for websites in 2022.

Core Web Vitals is a group of metrics established by Google to qualify the efficiency of websites, and it has been part of Google’s ranking algorithm since May 2021. More efficient and faster websites are rated higher, but ranking is not the only reason why specialists should know and care about Core Web Vitals: Google’s own studies show that pages that meet the Core Web Vitals criteria retain visitors as much as 24% more.

This is due to a better user experience, and can ultimately help you improve the rate of conversion from first-time visitors to potential customers.


What are the criteria for Core Web Vitals?

There are 3 metrics that make up Core Web Vitals: Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS). Each of them aims to evaluate a different aspect of the user experience, and together they aim to create a unified report on the quality and efficiency of a website. For a page to be considered well-optimised for Core Web Vitals, it should score over the 75th percentile in each of these criteria.

LCP represents the time between a visitor clicking on the website’s link from the Google search results to when it would be reasonable to conclude the majority of the content above the fold has finished loading. Google sets the threshold for a well-optimised website to have an LCP time below 2.5 seconds. This can be slowed down by content-based issues – such as scripts or high-quality images – or a slow server response time or low host speed.

FID is the response time to an interaction on the page. This can be the time it takes for a new page to load from the moment a link has been clicked, or a mailing form to pop up once a Contact Us button has been interacted with. An efficient website should have an FID below 100 milliseconds. Server and host-based inefficiencies affect FID as they do with LCP, and addressing one of these criteria can usually improve both scores.

CLS is a metric that aims to quantify how stable a page’s layout is during loading. For example, pages with advertisements slowly loading and covering or moving text and content will have a poor CLS score. A good CLS score should be below 0.1, and it can be worsened by bad CSS and Javascript optimisation, third-party pop-ups, widgets, and, most commonly, display ads.

How do I know how well my website scores for Core Web Vitals?

There are many ways improvements can be implemented to address issues regarding each of these metrics, but, firstly, an updated and detailed report about the current website’s efficiency compared to the Core Web Vitals thresholds should be produced. Google itself creates reports about websites’ Core Web Vitals with what it calls the Chrome User Experience Report – CrUX for short. This report is constructed from data from real visitors that have viewed and interacted with the page over the last month, and it is what Google uses to dictate the website’s search result ranking – this makes CrUX the most reliable tool to evaluate a site for Core Web Vitals score.

A report can be obtained through the ad hoc online tool from Google, or by using the Core Web Vitals function within the Google Search Console. PageSpeed Insights can also generate a reliable report, as can the third-party service GT Metrix – the latter only allowing for a desktop-centred report with its free plan.

Another way to assess a website’s Core Web Vitals optimisation is by employing Lab Measurement Tools such as Google’s own Lighthouse: these can also produce reports, although they do not use real visitor data, but simply test the page for the Core Web Vitals main criteria through simulation. Using Lab Measurement Tools has 2 main advantages: testing a website’s efficiency ahead of publishing, and immediate response, without the 28-day latency of a CrUX report. It should be mentioned that these tools cannot test for FID, but instead use Total Blocking Time (TBT): this metric can still identify issues that will affect FID, and can be used as a somewhat reliable assessment.

How can I improve my Core Web Vitals score?

Many solutions can be employed to address a poor or improvable score in any of the criteria. As mentioned earlier, many of the problems that can lead to a poor LCP or FID score derive from low host speed or inadequate server response time, therefore addressing these issues can help a website score higher in both categories. Some of the most common solutions to easily address these in a WordPress-based page are caching and lazy loading – both of these features are present in the popular plug-in WP Rocket.

Caching refers to the practice of processing frequently requested information and storing it in temporary memory; this allows for generally quicker loading times, and an overall smoother user experience.

Lazy Loading is a method that enables a website to initially only load the visible content of a page, instead of the whole page at once. This also means shorter response times for visitors.

Other easily actable solutions include deferring or deleting unused scripts, compressing high-quality images, and, if necessary, upgrading to HTTPS.


While Core Web Vitals does not, in itself, represent the greatest impact on a website’s SEO, early adoption can give a website the edge over its competitors, especially for niche keywords. Google stated that the definitions and criteria that constitute Core Web Vitals are expected to be stable, and any developments will be announced in a “predictable, annual cadence”: this principle can only be an advantage to early adopters to the optimisation criteria, who will be able to create efficient and high SEO ranking websites, with higher conversion rates for visitors and an overall better, more pleasant user experience

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