Comparing Search Volumes for 72k Keywords [A Study by Ahrefs]

There are two sources of keyword search volume data that comes directly from Google: Google Search Console (Terms of Service) and Google Keyword Planner (GKP). We decided to compare the numbers between the two and see how much they match.

Terms of Service is widely regarded as the “single source of truth” for accurate keyword data as it shows you the exact number of times your page has appeared in Google search results for a particular keyword.

So if your page ranks consistently on the first page of Google for a particular search query, the number of impressions for that search query is in Terms of Service should accurately reflect the search volume (in most cases).

As for GKP, is known to have much less accurate search volume data. Mainly because:

  • It groups keywords with similar meanings.
  • It rounds search volumes in buckets.

And yet many SEO Professionals are completely satisfied with the search volumes they get GKP and think they are right.

So we decided to do a little experiment and see how the search volume of GKP against the “Single Source of Truth”, aka Terms of Service.

Comparison of search volumes between Terms of Service and GKP

For this experiment we have 72,635 random keywords in the 1K to 10K Search volume range. Then we compared the number of “impressions” in Terms of Service with the search volume data of GKP (for the same month).

The first thing we found is this GKP Almost always overestimates the “true” search volume:

Bar charts with 91.45% of the search volume in GKP are overestimations

But the real question is by how much? Because if it just slightly overestimates search volume, what’s the big deal?

Here is the answer:

Bar chart, where GKP dramatically overestimates search volume 54.28% of the time, is approximately accurate 45.22% of the time

Most search volumes in GKP (54.28%) are overestimations, while almost half (45.22%) are approximately correct (i.e. deviating from Terms of Service “Impressions” by no more than 50%).

For the SEO Nerds among you, here’s a more detailed view of how Terms of Service Compare data with GKP:

Bart diagram with a big difference in search volume between GKP and GSC

Quite a discrepancy, right?

So why not dig a little deeper and examine the real causes of such a large difference in search volumes between GKP and Terms of Service?

GKP groups keywords with similar meaning (and makes mistakes)

According to our Terms of Service Data, the key word “ahrefs” 25,436 impressions in June (in the US):

GSC data on all impressions from Ahrefs

But if we look at the data from. look at GKP for the same month a search volume of 33,100 is shown:

GKP data on Ahrefs' total search volume

This means that the “GKP/Terms of Service”Ratio for that keyword is 1.3x. Not bad, but not very accurate either.

So what is causing this discrepancy?

Apparently it is GKP The search volume for the keyword “ahrefs” includes the search volume of all of its misspellings that we found in our Terms of Service:

  • ahref (2,826 impressions)
  • hrefs (906 impressions)
  • aherfs (435 impressions)
  • arefs (267 impressions)
  • a hrefs (224 impressions)
  • aherf (185 impressions)
  • ahrfs (100 impressions)
  • Etc

We know that because GKP group them together (and shows the same search volume it shows for “ahrefs”):

List of misspellings of

But when a keyword’s search volume takes into account its misspellings, that’s not that big of a deal, is it? In fact, it can be very useful.

Well there are some cases where GKP groups things that shouldn’t be grouped. And that can be misleading for us SEOs.

For example, the keyword “chusky” has a search volume of 550,000 in the US GKP believes that the spelling of “husky” is incorrect because these two keywords are grouped together:

However, if you look at the search results for the keyword “chusky” you will immediately see that it is not a typo. Rather, it is a unique breed of dog, which means it should have its own search volume.

Pictures of Chusky dogs

The same story with these four keywords: “red room”, “red rose”, “red rock” and “red robin”:

GKP treats them as one, but you don’t even have to check the search results to know that these things are not the same.

A few more examples:

  • American banks & Bank of America
  • Mosquito bites & Mosquito bites
  • book a driver & Logbook

To be honest, these types of “false groupings” are not common, but they can give you a lot of headaches if you stumble upon one of them.

Much more common (and irritating) that is GKP does not show different search volumes for closely related search query variants.

For example, the following searches are summarized in GKP without the possibility to see individual search volumes:

  • Download PC games for free
  • Free download of PC games
  • Free games download for PC
  • Download free games for PC
  • Free pc game downloads
  • Download PC games for free
  • free games to download for pc
Variations of

This “grouping problem” is then taken up by everyone SEO that also extracts its search volume data GKP (and almost everyone does that).

But here at Ahrefs we mix keyword data from multiple sources (including longstanding historical clickstream data). In this way we can “undo” searches and show the different search volume for each variation:

Table in which Ahrefs, in contrast to SEMrush, provides different search volumes for each query

Knowing the different search volume of each individual search query prevents you from accidentally overestimating the total search traffic potential of a topic when adding up the search volumes of all keywords in a group.

Aside from that, knowing the most common ways people formulate their searches can help you customize the language of your page and create a more eye-catching page title.

As you can see, this “grouping” feature is in GKP can be frustrating for us SEOs. But it’s not like we can blame ourselves for it GKP to hide exact search volumes from us. GKP is a tool for advertisers, not SEOs. And this grouping of similar keywords actually comes in handy for them.

Terms of Service shows local impressions for searches with local intent

Corresponding GKP, the keyword “golf courses” has an impressive average monthly search volume of one million in the US:

Data with keyword

But here’s the thing. Depending on where you’re looking from, you’ll see different page rankings for that keyword:

  • If you are looking for Rochester, You see one side of at 2 o’clock.
  • If you are looking for Bakersfield, You see one side of at 1.
Top 5 sites in Rochester and Bakersfield

Thus, the owners of these two websites see a different number of monthly impressions for the keyword “golf courses” in theirs Terms of Service. That’s because every website only ranks well in one specific location for that keyword.

And just like the owner of a huge website (which seems to have page ranking for “golf courses” in every imaginable place) would likely see a number of impressions close to 1 million GKP show us.

These “regional” keywords caused the largest discrepancy (4x +) between GKP and Terms of Service Numbers that can be seen in our graph above.

Impressions ”in Terms of Service are sometimes bloated by bot traffic

Let’s talk about the rare cases where Terms of Service shows a higher search volume than GKP.

We believe this is likely due to bot traffic. According to John Mueller, not all impressions are filtered by bots Terms of Service:

But what is “bot traffic”?

Well, that’s any type of script or software program that does automated searches on Google.

The “bots” you are sure to be familiar with are rank trackers that perform automated searches on Google to report where your website is ranked.

A much worse example is bots that generate fake clicks on Google ads to put pressure on their competitors.

Anyway, according to our study Terms of Service Data only appear to be artificially bloated 0.5% of the time. So it is unlikely that you will suffer much from bots polluting yours Terms of Service reported.

How does Ahrefs’ search volume data stack up?

I’m sure some of you are wondering how Ahrefs’ search volume data compares.

Well, let’s “Ahrefs /Terms of Service“Conditions right next to”GKP/Terms of Service“Relationships from the previous graphic:

Bar chart with Ahrefs is more accurate than GKP

It looks like Ahrefs will show “roughly accurate” values ​​60% of the time, versus 45% of the time for GKP.

This is mainly due to our ability to “pick up” clusters of similar keywords and report different search volumes for each one.

So if you were wondering why the search volumes in Ahrefs are not the same as in GKP, now you know that this is by design.

Final thoughts

Hope you enjoyed this research study and got a better understanding of how the numbers are in Terms of Service and GKP differ and above all why They are different.

Have any questions? Ping me on twitter.

And besides, Thanks very much to our great data science team who took some time out of their busy schedule to help me with this research.