Key Takeaways
Winner: SEMrush emerged as the most accurate, Ubersuggest was reliable except for one major blunder, and Ahrefs was least reliable by far. Keyword Surfer is still recommended because its free and easy to access.
Experiment Overview: Analyzed 80 U.S.-specific keywords across different lengths using five keyword research tools, comparing against Google Keyword Planner’s data.
Methodology and Mismatch Rates: Tools differed in their search volume calculation methods, with Ahrefs showing the most mismatches (30%), followed by Keyword Surfer (10%), and KWFinder (6.25%). SEMrush aligned perfectly with Google, while Ubersuggest had only one significant error.
Major Discrepancies and Blunders: Notable errors included underestimation of search volumes for specific keywords by Ahrefs and KWFinder, and zero volume reports for high-search terms like “computer repair” and “download youtube videos” by Keyword Surfer and Ubersuggest.
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Experiment Parameters
Ever wondered where your favorite keyword research tool gets its search volume data, and more importantly, can you trust it?
I conducted an experiment with five popular keyword research tools to find out.
I selected 80 random keywords divided into 4 categories (20 keywords each):
- One-word keywords
- Two-word keywords
- Three-word keywords
- Five-word keywords
These categories were chosen to encompass both short-tail and long-tail keywords.
The keywords ranged from millions to thousands of monthly searches.
My method involved comparing data from these tools with Google Keyword Planner’s search volume data.
Note that Google Keyword Planner provides search volume in ranges (e.g., 0-10, 10-100, etc.), which doesn’t offer an “exact” estimate, slightly affecting the comparison.
However, I used Google’s data as a reference point for useful insights, despite this limitation.
Important: The search volumes in this experiment are specific to the United States only.
How is Search Volume Calculated?
Different tools have varied methods for calculating search volume.
- Google Keyword Planner shows average monthly searches for your keyword and its close variants.
- KWFinder utilizes Google’s data and other sources, showing separate volumes for each keyword without including close variants.
- Ahrefs combines anonymized data from browser apps and plugins with Google’s data to generate their estimates.
- Semrush uses clickstream data and machine learning for their calculations.
- Keyword Surfer and Ubersuggest haven’t disclosed their methods, but likely follow similar practices to the others.
Now, let’s dive into the experiment results!
Experiment Results
Note: Red numbers mean there was a mismatch in search volume figures between the Google Keyword Planner and the respective tool.
One-Word Keywords
As you can see, Ahrefs search volume figures mismatched with those of Google Keyword Planner 6 out of 20 times in this batch of keywords.
Keyword Surfer’s data mismatched once.
Note: For some reason, all of the tools severely overestimate the search volume for the very first keyword which is “youtube.” Additionally, for reasons unknown, Google Keyword Planner did not want to show any estimate for the keyword “computer.”
Two-Word Keywords
Again, Ahrefs mismatched more often than others, 5 times.
Keyword Surfer mismatched 3 times.
KWFinder mismatched twice and Ubersuggest mismatched once.
Note: “Computer repair” keyword returned the oddest results. First, Google Keyword Finder refused to show any estimate for it, and then Keyword Surfer and Ubersuggest returned search volume of zero for that keyword, which can’t be correct. People do search for “computer repair” quite often. The reasons for these discrepancies are unknown.
Three-Word Keywords
Ahrefs mismatched 5 times.
Keyword Surfer mismatched twice.
KWFinder mismatched once.
A couple of very odd results were uncovered in this batch of keywords.
Keyword Surfer returned the search volume of 0 for the “download youtube videos” keyword and KWFinder returned the search volume of 10 for the “college football scores” keyword.
Both results are severely wrong since the search volume for both of these keywords is measured in millions.
Five-Word Keywords
Ahrefs mismatched 8 times.
Keyword Surfer and KWFinder mismatched twice.
The largest mismatched in this final batch comes from Keyword Surfer that has returned the search volume of 0 for the “legend quest masters of myth” keyword.
Other tools show that this keyword indeed does have some search volume behind it.
Key takeaways and statistics
Ahrefs mismatched with Google Keyword Planner for 24 out of 80 keywords or 30% of the time.
Keyword Surfer mismatched 8 different times or 10% of the time.
KWFinder mismatched 5 different times or 6.25% of the time.
Ubersuggest only mismatched once which is 1.25% of the time.
SEMrush did not have any mismatches and was within margins of the Google Keyword Planner for all 80 keywords.
Ahrefs was the tool that regularly returned the lowest search volume estimates out of all of the five tools – 39 out of 80 times, or 48.75%.
Ubersuggest only had a single mismatch, but it was quite a blunder.
It returned 0 search volume for the “computer repair” keyword.
Keyword Surfer made the exact same blunder.
The saving grace, in this case, might lay in the fact that Google Keyword Planner also refused to return any estimates for this keyword which indicates that, for some reason, many tools are having problems with this keyword.
Two similar blunders that are inexcusable belong to Keyword Surfer (again) and KWFinder that returned 0 and 10 search volume for the “download youtube videos” and “college football scores” respectively.
Both of these keywords have hundreds of thousands (if not millions) of searches per month.
Quite a few times, there were huge discrepancies between values shown by different tools. Here are a few examples:
Ahrefs returned 6-8X less search volume than other tools for the keyword “coffee.”
KWFinder returned anywhere from 24X to the staggering 238X less search volume than other tools for the keyword “sky scanner.”
Ahrefs returned about 4X lower search volume numbers than other tools for the keyword “cooking a turkey.”
KWFinder returned anywhere from 5.5X to a whopping 21X lower search volume number than other tools for the “best youtube to mp3 converter” keyword.
Final Verdict – Which Tool is the Best?
SEMrush wins the title, being consistently aligned with Google’s reported search volume data.
Ubersuggest ranks second, with just one mismatch.
Ahrefs, however, had the most mismatches by far.
Still, it’s important to recognize that Ahrefs remains a valuable tool and shouldn’t be overlooked.
For those focusing specifically on search volume tools, Keyword Surfer emerges as the top choice. It’s free and easily accessible as a Google Chrome extension on their official page.
Additionally, Google Keyword Planner is a viable option, available for free, if you’re okay with volume brackets rather than the precise estimates provided by other tools.