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How Reliable is Google’s SEO Score?

Google’s tool offers an SEO score. The score offers a score from 0 to 100.  What does the tool measure for the SEO metric and how useful is it?

What is SEO?

What do you expect an SEO score to mean? That depends on how you define SEO.

Moz defines SEO within the context of traffic:

What is SEO?
Search engine optimization (SEO) is the practice of increasing the quantity and quality of traffic to your website through organic search engine results.”

Unlike Moz, Wikipedia defines SEO within the context of visibility on a search ranking. Search engine visibility is a euphemism for ranking on a search engine.

“Search engine optimization (SEO) is the process of affecting the online visibility of a website or a web page in a web search engine’s unpaid results—often referred to as “natural”, “organic”, or “earned” results”

Search Engine Journal defines SEO as:

“The process of optimizing a website… so it will appear in prominent positions in the organic results of search engines. Successful SEO makes a site appealing to users and search engines.”

  1. Moz’s definition of SEO focuses on traffic.
  2. Wikipedia’s definition is about search engine rankings.
  3. SearchEngineJournal’s definition of SEO focuses on ranking and on being appealing to users.

Search Engine Journal’s definition is interesting because it recognizes how important it is to appeal to users. Google’s search rankings are primarily about ranking what users expect to see. If users don’t see what appeals to them then they are disappointed.

How Does Google Define SEO?

Google’s SEO Starter Guide defines SEO as:

“Search Engine Optimization is about helping search engines understand and present content.”

Understanding content means writing the content in a way that is clear and focused. It may also include adding images, structured data and meta data that helps the search engine understand what a page is about.

Google’s site defines SEO in terms of how easy a site is to crawl, how easy it is for the content to be understood, for the purpose of bringing more traffic.

Here is how Google’s Web Dev site defines SEO:

“Making your content discoverable matters because it’s how you get more relevant users viewing your content…

By making sure search engines can find and automatically understand your content, you are improving the visibility of your site for relevant searches.

This is called SEO, or search engine optimization, which can result in more interested users coming to your site. Audit your site and check the SEO results to see how well search engines can surface your content.”

What does the SEO Score Measure? is based on Google’s Chrome Lighthouse extension. According to the official Lighthouse page, these are are the nine factors Google uses to create the SEO score:

  1. Document Does Not Have A Meta Description
  2. Document Doesn’t Have A Title Element
  3. Document doesn’t have a valid hreflang
  4. Document doesn’t have a valid rel=canonical
  5. Document Doesn’t Use Legible Font Sizes
  6. Document uses plugins (Flash)
  7. Links Do Not Have Descriptive Text
  8. Page has unsuccessful HTTP status code
  9. Page is blocked from indexing

What Does the SEO Score Mean?

According to the definition, Google’s SEO score is a measure of how well search engines can “surface” content.

What does Google mean by surface? Does Google mean how well it can rank content? Or does Google mean how well it can discover content?

I believe Google means that the SEO score is a measure of how well Google can crawl and discover content.

Google’s main page defines SEO as:

“Checks for best practices to ensure your site is discoverable.”

The next page defines discoverability as:

“Easily discoverable
Ensure users can find your site easily through search.”

That is an artfully vague description of what it means to be discoverable. Does Google mean ranking? Or does Google mean making the content discoverable so that if other ranking factors align users can find the content through search.

Google is vague on the issue of what SEO is.

Publishers understand the concept of SEO within the context of ranking and traffic. Google’s Web.Dev page does NOT use the word Rank anywhere on its site. That is a curious omission for a tool that offers an SEO metric.


Google does not use the words rank or ranking anywhere on the site. I believe that this is a conscious omission on the part of Google.

The site not referencing SEO in the context of ranking. It is referencing SEO in the context of crawling and making content easy to understand.

Searching for the words rank and ranking yield zero results.

Google’s Web.Dev site does NOT use the word Ranking anywhere on its site either. Publishers are concerned with ranking. But Google is silent. This is to be expected. But it’s somewhat less expected considering that Google is offering an SEO metric to the SEO community .

Searching for the word Discoverability yields two results.

It is clear that Google’s SEO results are not concerned with ranking.

Page Scores 90 and Ranks #85

Here is a screenshot of a web page that ranks #85 in Google for the phrase how to diagnose arthritis.

Here is the SEO score of that .edu web page that ranks #85:

As you can see, the web page scores 90 for SEO. The only reason it didn’t rank 100 is because it was missing a meta description tag.

A meta description isn’t even necessary for ranking. Yet it still counts for 10% of the SEO score.  This makes it clear that the SEO score is based on a definition of SEO that has less to do with ranking and traffic (how SEO is defined) and more to do with crawling and indexing, otherwise known as discoverability.

Is Web.Dev SEO Score a Useful Metric?

The answer depends on how you define SEO. Google’s definition appears to be if your title tag and meta description exist and if Google can access the page. That’s a limited definition of SEO.

The SEO industry and Wikipedia start at Google’s definition then expand it to traffic, ranking and user satisfaction.

It’s naive to expect Google to provide an SEO tool that gives a clear answer as to how likely a page might rank. That’s probably one of the reasons Google removed the PageRank meter from it’s toolbar.

Google’s SEO score does not conform to the definition of SEO. That’s a more accurate description of the tool.

The SEO score is not an indicator of how likely a page will be able to rank. A page that ranks #85 is proof of that.

Rankings and traffic are the two qualities the SEO industry associates with the word SEO. offers no insights into those factors.

It may be more accurate if Google’s’s SEO score were rebranded as an Indexability or Discoverability Score.

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Category News SEO
SEJ STAFF Roger Montti Owner - at

I have 25 years hands-on experience in SEO and have kept on  top of the evolution of search every step ...

How Reliable is Google’s SEO Score?

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