We Analyzed 208K Webpages. Here’s What We Learned About Core Web Vitals and UX

core web vitals 2021

We analyzed 208,085 webpages to study more about Core Web Vitals.

First, we established benchmarks for Cumulative Layout Shift, First Input Delay, and Largest Contentful Paint.

Then, we seemed into the correlation between Core Web Vitals and person expertise metrics (like bounce price).

Thanks to information supplied by WebCEO, we have been capable of uncover some fascinating findings.

Let’s dive proper into the information.

Here is a Summary of Our Key Findings:

1. 53.77% of web sites had Largest Contentful Paint (LCP) rating. 46.23% of web sites had “poor” or “needs improvement” LCP scores.

2. 53.85% of internet sites in our information set had optimum First Input Delay (FID) scores. Only 8.57% of web sites had a “poor” FID rating.

3. 65.13% of analyzed websites boasted good optimum Cumulative Layout Shift (CLS) scores.

4. The common LCP of the websites we analyzed clocked in at 2,386 milliseconds.

5. Average FID was 137.74 milliseconds.

6. The imply CLS rating was 0.14. This is barely increased than the optimum rating.

7. The most typical points impacting LCP have been excessive request counts and massive switch sizes.

8. Large format shifts have been the #1 reason behind poor CLS scores.

9. The most typical situation affecting FID was an inefficient cache coverage.

10. There was a weak correlation between Core Web Vital scores and UX metrics.

11. We did discover that FID did are likely to barely correlate with web page views.

53.77% of Websites Had an Optimal Largest Contentful Paint Score

Our first aim was to see how every web site carried out primarily based on the three factors that make up Google’s Core Web Vitals: Largest Contentful Paint, Cumulative Layout Shift, and First Input Delay.

Core web vitals are part of Google's overall evaluation of "page experience"

Specifically, we wished to find out the share of pages that have been categorised as “good”, “needs improvement” and “poor” inside of every web site’s Search Console.

To do that, we analyzed anonymized Google Search Console information from 208k pages (roughly 20k whole websites).

Our first activity: analyze LCP (Large Contentful Paint). In easy phrases, LCP measures how lengthy it takes a web page to load its seen content material.

Here’s how the websites that we analyzed fared:

53.77% of websites had an optimal largest contentful paint score
  • Good: 53.77%
  • Needs Improvement: 28.76%
  • Poor: 17.47%

As you may see, nearly all of websites that we checked out had a “good” LCP score. This was increased than anticipated, particularly when taking into consideration different benchmarking efforts (like this one by iProspect).

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It could also be that the web sites in our dataset are particularly diligent about web page efficiency. Or it could be partly resulting from a pattern dimension distinction (the iProspect evaluation repeatedly displays 1,500 websites. We analyzed 20,000+).

Either approach, it’s encouraging to see that solely about half of all web sites have to work on their LCP.

53.85% of Websites We Analyzed Had Good First Input Delay Ratings

Next, we checked out Search Console reported First Input Delay (FID) scores. As the identify suggests, FIP measures the delay between the primary request and a person having the ability to enter one thing (like typing in a username).

Here’s a breakdown of FID scores from our dataset:

53.85% of websites we analyzed had good first input delay ratings
  • Good: 53.85%
  • Needs Improvement: 37.58%
  • Poor: 8.57%

Again, simply over half of the websites we checked out had “good” FID scores.

Interestingly, only a few (8.57%) had “poor” scores. This exhibits {that a} comparatively small variety of websites are more likely to be negatively affected as soon as Google incorporates FID into their algorithm.

65.13% of Sites Had an Optimal Cumulative Layout Shift Score

Finally, we seemed on the Cumulative Layout Shift (CLS) scores from Search Console.

CLS is a measurement of how parts on a web page transfer whereas loading. Pages which are comparatively steady by means of the loading course of have excessive (good) CLS scores.

Here have been the CLS scores among the many websites that we analyzed:

65.13% of sites-had an optimal cumulative layout shift score
  • Good: 65.13%
  • Needs Improvement: 17.03%
  • Poor: 17.84%

Among the three Core Web Vitals scores, CLS tended to be the least problematic. In reality, solely round 35% of the websites that we analyzed have to work on their CLS.

Average LCP Is 2,836 Milliseconds

Next, we wished to ascertain benchmarks for every Core Web Vital metric. As talked about above, Google has created their own set of guidelines for every Core Web Vital.

(For instance, a “good” LCP is taken into account to be underneath 2.5 seconds.)

However, we hadn’t seen a large-scale evaluation that tried to benchmark every Core Web Vital metric “in the wild”.

First, we benchmarked LCP scores for the websites in our database.

Among the websites that we analyzed, the typical LCP turned out to be 2,836 Milliseconds (2.8 seconds).

Average LCP is 2.836 milliseconds

Here have been the most typical points that negatively impacted LCP efficiency:

Issues affecting LCP
  • High request counts and massive switch sizes (100% of pages)
  • High community round-trip time (100% of pages)
  • Critical request chains (98.9% of pages)
  • High preliminary server response time (57.4% of pages)
  • Images not served in next-gen format (44.6% of pages)

Overall, 100% of pages had excessive LCP scores a minimum of partly resulting from “High request counts and large transfer sizes”. In different phrases, pages which are heavy with extra code, massive file sizes, or each.

This discovering is consistent with one other evaluation that we did which discovered that giant pages tended to be the perpetrator behind most slow-loading pages.

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Average FID Is 137.4 Milliseconds

We then checked out FID scores among the many pages in our dataset.

Overall, the imply First Input Delay was 137.4 milliseconds:

Average FID is 137.4 milliseconds

Here are essentially the most prevalent FID-related points that we found:

Issues affecting FID
  • Inefficient cache coverage (87.4% of pages)
  • Long main-thread duties (78.4% of pages)
  • Unused JavaScript (54.1% of pages)
  • Unused CSS (38.7% of pages)
  • Excessive Document Object Model dimension (22.3% of pages)

It was fascinating to see that caching points tended to negatively have an effect on FID more than some other drawback. And, not surprisingly, poorly-optimized code (within the type of unused JS and CSS) was behind many excessive FID scores.

Average CLS Is .14

We found that the typical CLS rating is .14.

Average CLS is .14

This metric particularly appears at how the content material on a web page “shifts”.Anything under .1 is rated as “good” in Search Console.

The most typical points affecting the initiatives’ CLS included:

Issues affecting CLS
  • Large format shifts (94.5% of pages)
  • Render-blocking assets (86.3% of pages)
  • Text hidden throughout internet font load (82.6% of pages)
  • Not preloaded key requests (26.7% of pages)
  • Improperly sized pictures (24.7% of pages)

How LCP Correlates With User Behavior

Now that benchmarks have been set, we then set to learn the way precisely Core Web Vitals characterize real-life person expertise.

In reality, this relationship is one thing that Google themselves spotlight of their “Core Web Vitals report” documentation:

Google – Why page performance matters

To analyze Core Web Vitals and their influence on UX, we determined to have a look at three UX metrics designed to characterize person habits on webpages:

  • Bounce price (% of customers leaving an internet site’s web page upon visiting it)
  • Page depth per session (what number of pages customers see earlier than leaving the web site)
  • Time on web site (how a lot time customers spend on an internet site in a single session)

Our speculation was as follows: should you enhance an internet site’s Core Web Vitals, it would positively have an effect on UX metrics.

In different phrases, a web site with “good” Core Web Vitals could have a decrease bounce price, longer periods, and increased web page views. Fortunately, along with Search Console information, this information set additionally contained UX metrics from Google Analytics.

Then, we merely needed to evaluate every web site’s Core Web Vitals in opposition to every UX metric. You can discover our outcomes for LCP under:

LCP and Bounce Rate

Correlation between LCP and bounce rate

LCP and Pages per Session

Correlation between LCP and pages per session

LCP and Time on Site

Correlation between LCP and time on site

On the three graphs, it was clear that each one three completely different segments (Good, Poor and Needs Improvement) are considerably evenly distributed on the graph.

In different phrases, there wasn’t any direct relationship between LCP and UX metrics.

FID Has a Slight Relationship With Page Views

Next, we seemed on the potential relationship between First Input Delay and person habits.

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Like with LCP, it’s logical {that a} poor FID would negatively influence UX metrics (particularly bounce price).

A person that should wait to select from a menu or kind of their password is more likely to develop into annoyed and bounce. And if that have carries throughout a number of pages, it could result in them lowering their whole web page views.

With that, right here’s how FID correlated with their behavioral metrics.

FID and Bounce Rate

Correlation between FID and bounce rate

FID and Pages per Session

Correlation between FID and pages per session

Note: We discovered {that a} excessive FID tends to correlate with a low variety of pages per session. The reverse was additionally true.

FID and Time on Site

Correlation between FID and time on site

Overall, the one occasion the place we see hints of correlation is after we evaluate FID to the variety of pages seen per session. When it involves bounce price and time on web site, an internet site’s FID seems to don’t have any affect on person habits.

How CLS Impacts User Behavior

Next, we wished to analyze a possible hyperlink between CLS and person exercise.

It appears logical {that a} poor CLS would frustrate customers. And may due to this fact enhance bounce price and scale back session time.

However, we weren’t capable of finding any case research or large-scale evaluation that demonstrated that top CLS scores affect person habits. So we determined to run an evaluation that seemed for potential relationships between CLS, bounce price, “dwell time” and pages seen. Here’s what we discovered:

CLS and Bounce Rate

Correlation between CLS and bounce rate

CLS and Pages per Session

Correlation between CLS and pages per session

CLS and Time on Site

Correlation between CLS and time on site

Overall, we didn’t see any vital correlation between CLS, bounce price, time on web site, or web page views.


I hope you discovered this evaluation fascinating and helpful (particularly with Google’s Page Experience update on the best way).

Here’s a hyperlink to the raw data set that we used. Along with our methods.

I need to thank website positioning software program WebCEO for offering the information that made this business examine potential.

Overall, it was fascinating to see that many of the websites that we analyzed carried out comparatively effectively. And are largely prepared for the Google replace. And it was fascinating to search out that, whereas Core Web Vitals characterize metrics for a constructive UX on an internet site, we didn’t see any correlation with behavioral metrics.

Now I’d like to listen to from you:

What’s your primary takeaway from at present’s examine? Or perhaps you could have a query about one thing from the evaluation. Either approach, depart a remark under proper now.

Jerry Gordon

About Jerry Gordon

Webmaster, nature and tech lover. Jerry manages the day-to-day operations at DigiToolsadvisor. He loves enjoying his free time, but most of all, trying new tools to master.