Understanding Google Core Web Vitals and SEO Impact

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Regular Readers of our content may remember that we published an article last year about page speed and what is really important. We stand by that article. However, Google has a lot of market power, so when they change the algorithm we all have to respond. And like a global game of musical chairs, a few months back Google stopped the music and website developers everywhere gasped … there was new work to do.

Let’s get right to it.

What Are Google Core Web Vitals?

Ostensibly, Google has decided that the user experience should be a factor in search engine page ranking. Some people agree with this idea, many do not. But in May of 2020 Google updated their Google Page Speed Insight tools with new measurements of speed and experience as part of their official recommendations. Then in December they announced that those metrics would contribute to Search ranking scores. And since more than 86% of all global searches are conducted on Google and search is vital to website discovery, resistance is futile … we will all be assimilated.

In addition to the perhaps more easily observable aspects of page speed, Google has added three measure-points that we describe below.

Largest Contentful Paint — LCP

This is simply a measurement of how long it takes the single largest element on a page to load. For most sites this will be a header image or gallery at the top of the page. But it could also be another piece of larger content a bit lower on the page.

  • Less than or equal to 2.5 seconds = Good
  • Less than or equal to 4 seconds = Needs Improvement
  • More than 4 seconds = Poor

First Input Delay — FID

Some speed tools call this “Time to Engagement.” It is how long it takes before a visitor can fully engage with page content — scrolling, clicking buttons, tapping an expandable image, etc.

  • Less than or equal to 100 milliseconds = Good
  • Less than or equal to 300 milliseconds = Needs Improvement
  • More than 300 milliseconds = Poor

Cumulative Layout Shift — CLS

Have you ever visited a web page and seen things jump around as items load? We have. It can be especially frustrating if you are about to click a button and it suddenly jumps away from your finger or mouse because an ad size changed or a larger image loaded in the header. CLS measures all of this jumping around for the full time the page is displayed. Google believes that for a good user experience all that jumping should be finished quickly.

  • Less than or equal to 0.1 seconds = Good
  • Less than or equal to 0.25 seconds = Needs Improvement
  • More than 0.25 seconds = Poor

Generally speaking, these elements will be aggregated into a summary score. Top-performing sites ranked “Good” will be treated more favorably in search results than sites scored as “Needs Improvement,” and sites scored as “Poor” will be left crying in their conversions.


Are We Measuring the Right Things?

It is important to note that even though Google has well over 100k employees in North America alone, the Google empire is built on algorithms and automation. Real Google-human-ish eyes will not look at your site or tinker with your personal search rankings unless you somehow awake the dragon. So, that means that Google is not necessarily scoring sites on metrics that actually matter. Rather, they are scoring your site on the things that they CAN measure that may — or may not — be related to the quality of user experience. If, like us, you have a background in statistical analysis you know how dangerous that can be. Wrote and potentially arbitrary standardization enforced by market dominance is never a good thing.

We are dancing to the tune that the Google band is playing, but they play whatever the heck they want to and do not take requests.

Inconsistency of Scores

This one will drive you a little crazy.

You can run Google’s official report on your website several times and get different results — day to day and even minute to minute. In fairness, this can be true for many of the page speed scoring tools that developers use. This can be affected by many things outside your control:

  • The traffic to other sites on the same network or server.
  • Automated DNS routing adjustments.
  • Other processes running on your platform.
  • Etc.

Another problem with automated scoring systems is that there is neither appeal nor parole. Whatever score you receive at the time Google-bots scan you is the one that you have until it comes around again. This adds a lottery-like element of chance that no one is comfortable with. If you are scanned by a Google bot having a bad day and it tips you over from “good” to “moderate” or “moderate” to “bad” it might impact your rankings.

There may be a mitigating factor in that Google will be ultimately looking at aggregate scores that asses the performance based on 75% of the visits to a site. But we will see how this plays out in practice.

Suspicious Altruism

Google does nothing for free … not really. There is a popular saying in technology, “If you are not paying for the product, then you ARE the product.” The question becomes, how is Google benefitting?

Since Google is more secretive than the NSA, the tech community can only speculate. No one wants to anger the Dark Lords at Google HQ in Mountain View, but in hushed tones at tech conferences, there has been speculation regarding lightening the load on Google bots scanning the web and potential sophisticated tracking methodologies in the metadata of WebP formatted images that only Google’s algorithms have access to.


Ultimately, for most businesses the incentives are clearly in favor of conforming to Google’s new standards. Businesses that do will likely have a search discovery advantage in the near to medium term over competing businesses that do not. Importantly, the new rules apply to every page on your website.

Over the last few months we have received many more requests from businesses that want to prepare their websites for the impact of Google Web Core Vitals and its impact on SEO. We have helped sites go from ranking very poorly to scoring exceptionally well. If you need help improving the performance of your site or just have questions about page speed or Google Core Web Vitals, just let us know. We are always happy to help

Links and Additional Resources

Our article: “The Truth About Website Page Speed” from September 2020:

Google Search market share:

Number of Google Employees:

Google’s Page Speed Insights Report:

Google Search Console Help File on Google Core Web Vitals: