Google Core Web Vitals Explained

20th Aug, 2020
Author image
Ruth Chapman
Group Managing Director

Core Vitals

To keep its 1.7 billion users coming back day in and day out, Google has to provide the best service to its users. That’s why hundreds of factors (known as ranking signals) play a part in deciding which content best answers a user’s query. To make the most of this vast sea of qualified customers, website owners must adhere to a set of metrics to score and maintain a place in search engine results.

Here’s what you need to know about the algorithm change coming in 2021: core web vitals. While everyone seems to be talking about it, it’s also confusing to a lot of people. So let’s demystify it.


Will Google’s 2021 update affect my rankings?

Google has said that these changes will take place in 2021. Because of COVID-19, they have pushed back its release, and they want to give webmasters extra time to prepare. They have promised at least six months’ notice to prepare: as yet, we have not received that notice. When they do, we will update this post with more information.

As this update will affect regular search results on mobile and desktop, a lack of preparation could lead to a decline in keyword rankings, loss of search engine visibility and an increase in bounce rates.

To appear in Google Top Stories (the news that appears at the top of search results), you will need to meet a minimum threshold of Core Web Vitals. Previously, AMP was a requirement to rank here, but not anymore.


Core web vitals assess real-world page experience.

Page Experience in Google search results measures and analyses user behaviour on a webpage or results page. If the algorithm feels that the page couldn’t offer what the user was looking for, it means some changes are required. It also checks how users interact with the ranked landing pages.

In real-time, Google is assessing these Page Experience signals. It’s not so much about the text of the page, which are traditional ranking signals, but more about the user experience and how useful and usable a page is. Core web vitals can be summarised in three core foundations. But these are not standalone factors. They fall into the broader category of Page Experience, which includes:

  • Mobile-friendliness
  • Intrusive interstitials (pop-ups)


The 3 Pillars of Core Web Vitals

While these seem very technical, it’s easy to understand if you don’t get too hung up on the specifics. Read on for the three things that core web vitals measure.


1. How fast does the page load?

Largest Contentful Paint (LCP) measures the loading performance of a page’s main content. The most significant thing in the user’s view could be an image, video or text, on mobile or desktop. If your page loads within 2.5 seconds, it’s considered a strong LCP measurement. If it takes four or more seconds, it might need some work.


2. How fast is the page interactive?

First input delay (FID) measures the impression of your site when the user first interacts with a page. It tests the responsiveness and interactivity of the site, by measuring from the time a user clicks the link to the time a browser responds. When you click on something, it’s not a good experience when nothing happens, or it’s slow to load. FID measures the speed the browser can start to process that request to produce a result. 100 milliseconds or less is good, and 300 milliseconds and over is considered poor.


3. How fast is the page stable?

Cumulative layout shift (CLS) is all about visual stability. It quantifies those unexpected layout shifts. You know, when you’re reading an article and the page suddenly changes. Or you go to click a button, and at the last second, it shifts. Cumulative Layout Shift uses two measures of movement: Impact Fraction and Distance Fraction to measure its score. The CLS score of a site should not exceed 0.25. 0.1 or less is considered a robust CLS score.


Why are core web vitals important?

Even though page speed is a pretty small signal, as users experience it, it can have outsized influence. Google had shown, for example, that for pages meeting the core web vitals threshold, visitors are 24% less likely to abandon the site. You can gain 24% more traffic by merely making your website a little more usable.


So how can I put this into practice?

google search console


  1. Look for errors on the Core Web Vitals report on Google Search Console: the number one tool for diagnosing any problems with Core Web Vitals. Google has made this very, very simple to use, helping you find the pages that are poor, need improvement or have a good user experience. Every report in Search Console links to a report in Page Speed Insights.
  2. Chrome UX report: also referred to as CrUX. This was drafted by Google using millions of websites’ data. Anyone can access this data through the Public Google BigQuery project and PageSpeed Insights.
  3. Google has updated its developer tools to help site owners understand its requirements and optimise their page experience.

Webmasters have an opportunity here, to increase on-page engagement and conversions. You can enhance the experience for visitors, and the conversion rate for you. While you may be able to measure these issues yourself, a professional SEO service can help optimise your website.

If you need help preparing for the Google 2021 update or simply want to hear more about the ways of improving your Core Web Vitals, give us a call. We’d love to get into the nuts and bolts of Core Web Vitals to find what works for you.

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