Core Web Vitals (CWV) are the speed metrics that are part of Google’s Page Experience signals used to measure user experience. Metrics measure visual load with Largest Contentful Paint (LCP), visual stability with Cumulative Layout Shift (CLS), and interactivity with First Input Delay (FID).
We wanted to look at the data to see how websites were doing and if we could gather important information.
The data we used comes from the Chrome User Experience Report (CrUX), which is the source of Core Web Vitals’ data and is data from actual Chrome users.
In the public dataset, the data is aggregated at the source (domain) level. We also wanted to look at the data at the page level, so we collected over 5.2 million pages of vital web information in Ahrefs’ Site Audit.
We go down.
Overall, we have seen nearly 33% of websites break through the Core Web Vitals thresholds. This is up about 10% from the previous year, indicating that websites are getting faster.
The improvements are similar on desktop and mobile. Most of the attention in 2021 has focused on mobile results. But in general, the speed improvement on mobile pages also improves the speed on desktop pages.
Websites appear to be making progress in improving FID and CLS, but are struggling with LCP. I’m not really surprised by this. LCP has the largest number of components, making it the most difficult to repair.
Websites seem to have a little more trouble with LCP on mobile devices than desktops. It is probably due to the connection speed and mobile CPUs that have less processing power.
For FID, it appears that hardly anyone needs to worry about this metric in desktop versions, and very few need to focus on this metric in general.
CLS is similar on mobile and desktop.
When dividing Core Web Vitals by connection speed, hardly any sites on 3G or slower connections go through. If many of your users have slower connections or the internet in your country is slower, you will have to fight an uphill battle.
Here’s another way to look at the data with individual metrics broken down by connection speed. The LCP threshold seems nearly impossible to pass over slower connections.
Few sites have to worry about FID, even on slower connections.
Many sites have problems with CLS on slower connections.
The location of your users seems to have a big impact. Different countries have different device preferences and different network infrastructures. If your users are in a country where everyone is using desktop devices with fast internet, your website will most likely have good Core Web Vitals. The reverse is likely to be true for websites whose users all use older phones with slower connections.
The United States ranks 38th in the data with a pass rate of 41%. If you’re curious, here’s the full country data for August 2021.
Site audit data
A quick thank you to Oleksij Golovko for collecting this data from Ahrefs Site Audit. He pulled data from 43.66 million unique pages. We found that only 5.21 million (~ 11.9%) had at least one Core Web Vitals metric, and 93% of these (or ~ 4.85 million in total) had all three metrics.
We also noticed that all pages had LCP (99.79%) and CLS (99.91%) metrics. The metric, FID, was missing the most and only available on 93.08% of the pages that had Core Web Vitals metrics.
Fewer pages than the overall origins (domains) are passing the Core Web Vitals (only 21.2% of the pages). Not sure how to fully explain it. I suspect it may be due to caching where subpage loads tend to be faster.
For page-level data, LCP is similar to source data. FID is better and something that doesn’t seem to be a problem for most pages. CLS is worse in page-level data than in source data.
I wanted to study the impact of Core Web Vitals on rankings. But due to the timing of the launch and other updates that happened at the same time, I don’t think there is a good conclusive method. There are other studies that show a correlation between speed improvements and rankings. But saying this isn’t much different than saying that sites that are more likely to work on their SEO rank better than those that don’t.
If you want to log Core Web Vitals data for your site as you make improvements, you can enable the option in the Site Audit settings. All users, including free users, have access to this via Ahrefs Webmaster Tools.
If you’re having trouble improving your metrics or want to learn more about how pages load, check out our guide to page speed.
Which data surprised you the most? What data would you like to see if we update this study? Let me know on Twitter.