Google’s “search volume” estimates are not what you think


Google's Search Volume Estimates can be deceiving for SEOGoogle recently clarified its estimates for organic search traffic, and in doing so, it may just have pulled the rug from under many search-engine-optimization (SEO) programs. Apparently, the Search Volumes presented by Google’s Adwords Keyword Tool, used by many SEO “specialists” to estimate the size of the organic search market and justify their SEO programs, can overestimate the actual organic search market by a factor of 100!

For example, if you thought that the monthly search volume for a specific keyword phrase was 28,000 searches a month based on this Adwords keyword tool, you might just find the actual search volume is 280: a huge difference in market size!

The implication for marketing managers everywhere is that their return-on-marketing-investment (ROMI) calculations used to justify SEO programs could be deeply flawed.

I’ll get to the details in a minute, but first some background for those marketers not steeped in the world of SEO. (You might also want to check out our Glossary of SEO and SEM terms)

The importance of Search Volume and Search Volume Tools

Most Inbound Marketers agree that SEO is the most cost-effective long term investment to drive quality, relevant traffic to your website. More so than the other primary drivers of inbound traffic, namely Pay-per-Click advertising (PPC), and Social-Media-Marketing (SMM).  To justify their investment in SEO programs, SEO specialists around the world try to quantify the number of prospects a well-optimized website can attract.

To arrive at that number, SEO pros use a variety of tools to estimate search volume. One of the tools frequently used by SEO specialists is the Google Adwords Keyword Tool (GAKT).  As an example, see the following report for the search phrase “environmental equipment”:

Google's Adwords Keyword Tool and Search Volume Estimates

Result for the keyword phrase "environmental equipment" using Google's Adwords Keyword Tool

Note that the estimated “Local Search Volume” for the term “environmental equipment”, in April 2010, across the United States was 12,100 searches.

Now SEO professionals have know for some time, based on anecdotal evidence, that the search volume estimates produced by this Google Adwords Keyword Tool seemed a little high. But in the absence of better tools (and remember that Google represents 70%+ of the global search industry), these numbers are nonetheless used regularly to flaunt the size of the search market and justify investment in search engine optimization programs.

Google’s new insight on Search

Just over a year ago, Google introduced a beta of the new Search-based Keyword Tool (SKTool) with relatively little fanfare.  Initially targeted at some special applications, the SKTool did not replace the traditional Google Adwords Keyword Tool as a primary tool for determining search volumes. However, it was noted by SEO pros everywhere that the search volume estimates by SKTool were often drastically lower than the traditional Adwords Keyword Tool.

For example, using the same search phrase of “environmental equipment” above, the SKTool returns much, much smaller search volume estimates:

Google's Search-based Keyword Tool and Search Volume estimates for SEO

Results for keyword phrase "environmental equipment" using Google's Search-based Keyword Tool

That’s a drop from 12,100 searches a month to 155 searches a month!

Initially, Google’s explanation of the difference in search volume estimates between GAKT and SKTool was quite cryptic:

How does the Search-based Keyword Tool differ from the Keyword Tool in AdWords?

Answer: “The main difference between the Search-based Keyword Tool and the Keyword Tool currently in AdWords is that the former generates keyword ideas based on your website, and identifies those currently not being used in your AdWords account. Additionally, the Search-based Keyword Tool provides more detailed data for each keyword, such as category information, suggested bid that may place the ad in the top three spots of a search results page, and ad/search share. Both tools, however, offer the option of browsing all keywords across all categories”

You may also notice that some of the data (like such as the monthly search volume) may vary slightly between the two tools, which is due to different methods of calculation at this time (emphasis mine).

And the situation remained cryptic until Google very recently added this explanation to clarify the situation:

Why do search volume statistics vary between keyword tools?

Answer: “The updated Keyword Tool combines search data across and all affiliated search properties. Data from the Search-based Keyword Tool is based solely on searches on (emphasis mine). Numeric data between the tools may also differ due to rounding.”

HOLD THE PRESS! The full implications of that last sentence are that the search volume estimates that many have used to justify SEO programs are not based on Search Engine queries at all, but rather primarily on click-through rates on PPC ads on Google’s advertising network! There may be 11,945 (12,100 minus 155) click-throughs on various ads associated (loosely) with the keyword “environmental equipment”, but only 155 actual search engine queries. Thus the entire SEO potential for “environmental equipment” is 155 searches a month (US), not 12,100.

More practical examples

In case you think the above example using “environmental equipment” is a statistical outlier, here are a couple of other B2B search phrase examples:

Search Phrase

Monthly Search Volume (US – April 2010) based on Google’s Adwords Keyword Tool

Monthly Search Volume (US- April 2010) based on Google’s Search-based Keyword Tool

injection molding



marketing automation



fleet management software



Is SEO dead?

What does this mean to the $10+ billion global SEO industry?

In my view, this is not the death knell for the SEO business.  Achieving the #1 Search Engine Results Page (SERP) position in any of the above keywords will still generate a lot of relevant, valuable traffic to your website.

But it is a big reality check for the world of SEO, and will change every ROMI calculation used to justify an SEO campaign. And with Social Media (aka the “new search”) coming on strong, perhaps B2B companies need to take a closer look at Social Media Marketing as a driver of highly relevant traffic, in addition to SEO.

A reminder: A tool is only as good as the person using it

This post also serves as an important reminder of an issue we continue to emphasize at GossamarTools, no matter how cool, are useless in the wrong hands. Whether it is SEO traffic estimation tool, or marketing automation tools, a tool without expertise and a sound process behind it will deliver flawed results.

Unless you think the difference between 12,100 and 155 is minor.

Until next time – Axel

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