Core Web Vitals – what they are, and why they matter to you

Core Web Vitals are a set of three ‘real-world’ metrics which measure how usable a web page is when it is first loaded.

One of the best things about the web is that there is always something new to learn. One of the worse things about the web is… that there is always something new that you need to know about!

You may have heard about the push by Google to rewards sites that offer secure, enjoyable, and accessible experiences for users. For some time now, these and other factors such as mobile responsiveness, quality of adverts served on a website, page loading speed, and so on have been part of the secret sauce Google uses to decide where your website should rank in their search results.

They are now taking a major step forward with Core Web Vitals – a set of three ‘real-world’ metrics which measure how usable a web page is when it is first loaded.

So why is it relevant to you? If you’re reading this article, you probably have or need a complex digital platform – maybe an e-commerce site, large content-managed site, or some other significant web presence. The older and more complex your site is, the more likely that you have work to do as a result of this change. If you’re reliant on organic web traffic (i.e. traffic from search engines) for a material portion of your revenue, you could be at risk of seeing traffic and revenue drops if you don’t take action.

The good news? There are some great tools to help you, and fixing issues isn’t always overly complex.

What are Core Web Vitals?

There are three main areas that make up Core Web Vitals; Loading, Interactivity and Visual Stability.


Loading uses the metric ‘Largest Contentful Paint’, which is the time it takes to load the main part of your website visible on the screen. In simple terms, this is the time it takes from loading to your page looking like it’s ready for a visitor to interact with it. A good score is 2.5 seconds or less.


Interactivity is measured by ‘First Input Delay’, which is the time it takes for the site to be ready to respond to a user’s actions – a click on a link or button for example. In simple terms, this measures the delay between your user seeing your site, clicking (or typing) something, and the website processing that input. Often poorly-coded web pages will have lots of scripts which may cause significant delays in responsiveness. A good score is 100 milliseconds or less.

Visual Stability

Visual Stability is measured by ‘Cumulative Layout Shift’. A layout shift occurs when an element on the page moves unexpectedly, which could cause the user to misclick or have problems understanding the content. This measure sums up all the impact of unexpected layout shifts that occur, by assessing how much of a page is affected, and how big the difference is between the expected layout and the actual layout. You may have seen a page load slowly and the font change or a box change in size as the content is loaded. This is an example of poor visual stability. A good score is 0.1 or less.

How much impact will Core Web Vitals have on my traffic and revenue?

Truthfully, no one other than Google’s engineers can answer that (and they say “it depends”). But based on comments they have made so far, the general consensus is that we’re not going to see the ‘big bang’ ranking drop that some previous algorithm changes have caused.

Because search ranking is influenced by a number of factors, if you have an issue with Web Core Vitals you’re likely to see a slow but steady decline over the next 3-6 months. That decline may start to accelerate as more of your competitors improve their Core Web Vitals scores. As time passes, Google may also start to increase the weighting of Core Web Vitals in the overall algorithm, accelerating the decline further.

It’s worth noting that aside from Core Web Vitals, websites with great user experience (UX) generally convert much better. Users are getting much savvier, and they expect a slick experience from brands and service providers. Don’t take our word for it… here is a story about how UX improvements increased conversion by 75%. Just to put that in perspective – the same amount of visitors, 75% more sales.

So what should I do next?

A quick test on Google’s Lighthouse Audit tool will provide you with the stats for your site. If you work with an agency already or have an in-house team, they are probably already talking to you about this if it’s relevant to your site. The audit tool gives a list of actions that can help improve your score, and they will most likely have these in hand or done already.

Of course, if you don’t have anyone that can help or you need a second set of eyes we may be able to help you assess where you are. Our SEO & UX experts can help you assess the likely impact of Core Web Vitals on your site. If you need us, you know where to find us.