If you have a subscription to at least one of Ahrefs, Semrush and Moz, let’s start with a quick poll.

How many of these tools (SEMrush, Ahrefs and Moz) do you subscribe to?

If you only answered one or even two, do you know what keyword ranking data you’re missing out on? That is the central question this post aims to pose. It isn’t about which tool is the best 1. It’s about whether the best is good enough for you.

In this post, I compare the keyword rankings for six different URL groupings 2 across Semrush, Moz and Ahrefs. On average per ranking pull, 86% of keywords and 45% of the total search volume were exclusive to one tool! While Ahrefs led the way in these specific scenarios 3, it still only included an average of 59% of keywords and 73% of keyword volume. That means with only one tool, at best you could be missing out on 25-40% of available data. Yikes!

Methodology (or lack thereof)

I almost didn’t put a methodology section because this is so laughably unscientific. My goal was to compare keyword ranking data from these three tools across a diverse set of niches. In honor of all of the weddings that have been postponed or altered this year due to the pandemic, I used this age-old poem as a means to brainstorm the sample.

Poem Idea URL Path
Something old, Buffalo Trace 4 buffalotrace.com domain
something new, Covid-19 coronavirus.jhu.edu/map.html exact URL
something borrowed, Avis Car Rental avis.com/en/locations/us/ks path
something blue, Maurice from Little Monsters imdb.com/name/nm0005177/ exact URL
and a sixpence, Sixpence None the Richer sixpence-ntr.com domain
in her shoe. Women’s Flats dsw.com/en/us/category/womens-flats path

I pulled US ranking data according to the URL path specifications above. For volume, I took an average of each tool’s estimate. All rankings were pulled Between October 9th-10th, 2020.


I’m sure there are even more caveats and blind spots than what I have listed, but here are those that come to mind.

  • Small keyword sample size – Six disparate ranking pulls are obviously not predictive of what other queries may return.
  • Limited toolset – I didn’t include tools like Serpstat, KWFinder, Google Search Console and others. Keep this in mind when looking at the percentages of the charts in this post, as they are all likely inflated. In other words, the collective data among these three SEO tools does not represent 100% of all available ranking keywords.
  • More may not mean better – Some tools may show more keywords, but some of those rankings may be outdated.
  • Moz path limitations – Two of the six ranking pulls were for folder paths. Moz does not have this option; you can only choose between exact page, subdomain and root domain. In these cases, I pulled rankings for the entire domain and filtered by path, but hit the 50,000-row export limit. With that, the Avis and DSW data may not have included all of Moz’s keywords.
  • Different keyword volumes – Anecdotally, Moz has the most conservative keyword volume estimates, so its comparative unique keyword volume may be dampened as a result.
  • These tools do much more – Keep in mind Semrush, Ahrefs and Moz execute so many other overlapping SEO tasks. So, even if you have a favorite for keyword ranking data size and accuracy, you may have different preferences for keyword suggestions, keyword difficulty, estimated search volume, rank tracking, site audits, backlink data and so on.


Let’s dive into the data. The two metrics we’ll focus on are the number of keywords and the total keyword volume. Whenever you see the “Shared” delineation, I’m referring to metrics from keywords shared between two or more tools. Conversely, “Unique” means only one tool included this keyword ranking.

Overall Shared vs. Unique Keyword Ranking Breakdown

On average, only 14% of the keywords were in at least two SEO tools’ ranking data. That’s incredible! DSW had the largest contrast of shared vs. unique with over 97% of keywords found in only one of the tools.

Shared vs. Unique Keyword Ranking Breakdown bar chart

When it comes to volume, the disparity isn’t quite as egregious. This makes sense. The highest searched terms should be more likely to be picked up by multiple tools. DSW continues to be an outlier with 93% of the keyword volume found in one of the tools. On the other side of the coin, 90% of the Howie Mandel IMDB page ranking volume can be found in at least two of the tools.

Shared vs. Unique Keyword Volume Breakdown bar chart

Shared vs. Unique Keyword Ranking Breakdown by URL Grouping

Here’s a snapshot of each ranking pull. I’ve included a percentage breakdown between Shared (by two or more) and exclusive (broken out by tool). I also listed a notable keyword exclusively found by each tool.

Buffalo Trace Distillery (something old)

This includes all rankings on the https://www.buffalotrace.com/ subdomain.

bar chart of shared versus unique keyword ranking breakdown of buffalotrace.com

Source Notable Exclusive KW Rank MSV
Ahrefs buffalo trace bourbons 10 6,300
Moz buffalo trace barrel 6 445
Semrush buffalo trace experimental collection 2 720

Johns Hopkins University Coronavirus Map (something new) 5

This includes all ranking data on this exact URL: https://coronavirus.jhu.edu/map.html.

bar chart of shared versus unique keyword ranking breakdown of https://coronavirus.jhu.edu/map.html

Source Notable Exclusive KW Rank MSV
Ahrefs coronavirus death toll 1 198,000
Moz johns hopkins medical center 6 322
Semrush covid-19 5 5,000,000

Avis Kansas Locations (something borrowed)

This includes all ranking data within this folder path: https://www.avis.com/en/locations/us/ks.

bar chart of shared versus unique keyword ranking breakdown of https://www.avis.com/en/locations/us/ks

Source Notable Exclusive KW Rank MSV
Ahrefs olathe rental car 5 250
Moz witchita rental car 6 27
Semrush avis car rental in topeka ks 1 90

Howie Mandel IMDB Page (something blue)

This includes all ranking data on this exact URL: https://www.imdb.com/name/nm0005177/.

bar chart of shared versus unique keyword ranking breakdown of Howie Mandel's IMDB page

Source Notable Exclusive KW Rank MSV
Ahrefs howie mandel age 5 1,000
Moz who did the voice of gizmo 6 132
Semrush howie mandel show 5 720

Sixpence None the Richer Official Band Website (and a sixpence)

This includes all rankings on the http://sixpence-ntr.com/ subdomain.

bar chart of shared versus unique keyword ranking breakdown of the http://sixpence-ntr.com/ subdomain

Source Notable Exclusive KW Rank MSV
Ahrefs six pence band 5 60
Moz richers band 5 11
Semrush sixpence none the richer shirt 6 90

DSW Women’s Flats Category (for her shoe)

This includes all ranking data within this folder path: https://www.dsw.com/en/us/category/womens/flats.

bar chart of shared versus unique keyword ranking breakdown of https://www.dsw.com/en/us/category/womens/flats

Source Notable Exclusive KW Rank MSV
Ahrefs flats 1 21,000
Moz womens flats size 11 1 31
Semrush womens flats 1 18,750


I’ve done my best to be clear about what conclusions you shouldn’t draw from this small sample size and haphazardly approach. However, I do think these examples offer a few suggestions.

Get all of the tools

Insert obligatory ‘Why not both?’ GIF.

Listen. I get these tools are expensive, especially if you get more than one. I’m fortunate to have that luxury but understand many of us are not afforded it. However, when you’re weighing the pros and cons, I urge you to fight against the temptation to say these tools are fairly redundant. Their offerings are redundant; their data is highly unique.

If you can’t swing it, give all three a try for a short period of time to see what tools seem to cover your space most comprehensively. I promise the tool that wins out varies by niche.

Additionally, I would love for each of these tools to consider offering discounts to users who can prove they are subscribed to at least one competitor. What do they have to lose? A switch is hard to achieve, but a discounted add-on could be an easier alternative.

Don’t get comfortable

The best tool for you today may not be the best in the future. The arms race between these three tools is a sight to see, because SEO professionals are the real winners. Whether it’s from internal innovation or changes to external data sources (see: Jumpshot), these tools continue jostling past each other with new and improved data and functionality.

Show gratitude

At a time when Google continues to tighten its grips on data that would help us do our jobs more effectively, we’re blessed to have these incredible tools as options. Thanks a lot, Semrush, Ahrefs and Moz!

  1. Spoiler: My incredibly small keyword ranking sample painted Ahrefs in the most favorable light, followed by Semrush and then Moz. However, earlier this month Jeff Baker shared similar data with Moz in a comfortable lead. So as always, it depends.

  2. two domains, two folder paths and two exact URLs

  3. That is by no means representative of the entire corpus of keyword rankings these tools have.

  4. oldest continuously operating distillery in America

  5. To be honest, it’s getting old.