Why you need to optimise for Core Web Vitals right now

Thursday, April 1, 2021
Written by:
Digital Boutique

Recent research by Screaming Frog found that only 13% of sites have been optimised for Google’s June 2021 algorithm update. That’s a worryingly low number when the focus of the update is Core Web Vitals (CWV), metrics widely expected to make the difference between you and your competition. If you’re part of the 87% who haven’t yet given Core Web Vitals your attention, here’s what you need to know.

What are the Core Web Vitals?

Core Web Vitals is the collective name for three important page-experience metrics. Meeting the threshold for all three will push your site higher up the SERPs. Your listing will also be tagged to show your site offers a great on-page experience – giving you the chance to win customers from your competitors.

Meet the Core Web Vitals: LCP, FID and CLS

The three metrics for Core Web Vitals: Largest Contentful Paint (LCP), First Input Delay (FID) and Cumulative Layout Shift (CLS)
To pass Core Web Vitals, your Largest Contentful Paint score needs to be sub-2.5 sec, First Input Delay needs to be under 100 ms and Cumulative Layout Shift needs to be less than 0.1.

Largest Contentful Paint (LCP)

This measures how quickly your site loads its core content. You can check your score using the PageSpeed Insights tool. If your site is slow to load, you can also check what’s causing the problem – large, unoptimised images are a common culprit. Issues can also occur if Google chooses an LCP that doesn't align with the user perspective, or if core elements are repainted during load, which restarts the LCP clock.

First Input Delay (FID)

FID grades how long your visitors have to wait before they can click, type or scroll on your site. Important to note: your FID score is based on what your visitors actually experience rather than how your site performs in a test. This puts some factors out of your control - like device and connection speed but there’s still plenty you can do to improve a low grade – especially if you have developers to hand. Code splitting, for example, can allow interactions while the page is still loading to improve your score.

Cumulative Layout Shift (CLS)

This metric scores how much the items on your page move around during load – which can frustrate visitors and cause them to click on links by mistake.

Making sure all on-page elements load in their final position is key to improving your score here. Even shifts that are too small to see can affect your score, so we recommend checking out exactly what’s going on using the relevant section in PageSpeed Insights. 

The Google Core Web Vitals report for Amazon.co.uk showing that the site does not pass Core Web Vitals.

Core Web Vitals aren’t just good for SEO

Meeting the Core Web Vitals thresholds serves you in multiple ways. These metrics encourage a better on-page experience that will also improve your conversion rate and reduce your bounce rate.

“Users are 24% less likely to abandon page loads when Core Web Vitals pass” - Google

Optimise for mobile or risk desktop traffic

Your focus for CWV should be mobile, even if most of your revenue comes from desktop. That’s because Google seems to be rapidly moving towards mobile-only crawling. The search engine has already announced that desktop bots will crawl sites much less frequently. And it has warned against mobile content that’s a shortened version of your desktop site, saying these sites will lose rankings. In short, if you want your desktop site to rank well, you need to earn that ranking mobile.

The DB view

Wondering how concerned you should be about Core Web Vitals? Gary Landa, our head of strategy, has this advice:

“Google will no doubt keep us guessing so it will be interesting to see what impact the update has. But Core Web Vitals are potentially an excellent way to outmanoeuvre your competition.
"There are hundreds of different signals so there’s a chance that Core Web Vitals won’t immediately have a drastic impact, even on mobile. But long-term, we think CWV will be a crucial part of the SEO mix. We also think your CWV score will affect your quality score so it could reduce your Paid spend as well.
"To protect their ranking after the roll-out of CWB, we’re recommending that our clients optimise for LCP, FID and CLS and then keep a close eye on competitor traffic and rankings. This will help them understand the overall impact of Core Web Vitals in their sector.”‍

Roll-out is coming mid-June 2021

While you can test your site for LCP, FID and CLS now, the metrics won't affect your search ranking until Google updates its algorithm in June. Significantly, Google gave a whole year's notice of this update, despite being famously tight-lipped about algorithm changes. By giving businesses such a long time to prepare, they’ve strongly hinted that changes will impact SERP positions. This makes Core Web Vitals too important to ignore.


From quick wins to technical fixes, we’re helping our clients protect their discoverability after the June update. Visit Google’s PageSpeed Insights tool to see if your ecommerce site meets the Core Web Vitals thresholds.

If it doesn’t, there’s still time to take action.

Give us a call