Compare Keyword Difficulty Score Across Moz, Ahrefs, Ubersuggest, and SEMrush

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First, what is a keyword difficulty score?

Calculated by several leading SEO tools, keyword difficulty is a number from 0 to 100 that shows the relative level of competitive difficulty for ranking a given keyword on page one of Google’s results.

Assessing keyword difficulty is an important part of effective keyword research, and can often determine which keywords are reasonable to target on your website versus those that are out of reach.

The tricky part, however, is that each of the major SEO tools calculates this metric somewhat differently. For the same keyword, you might see a low score in one tool and a high score in another.

 

The Most Important Question: Which Tool Measures What?

Keyword difficulty is provided by almost all keyword research tools (and in all scales). It looks pretty easy – a low score means the keyword is easy to rank for. Before you get happy seeing low scores in green, you need to understand how the tool measures it.

Don’t skip reading the fine print or you risk being misled (particularly important when you’re deciding what kinds of content to start creating). It turns out that this information is not always easy to obtain because most tool owners consider it confidential.

After researching the 4 most popular tools in the SEO industry today, we compared their scores – all calculated with metrics based on their own databases and formulas.

Ahrefs Keyword Difficulty

Level of trust: Low

Ahrefs uses a scale from 0 to 100 to determine keyword difficulty score. They also measure the average number of backlinks for the top 10 ranking URLs. If the average number is low, the tool tells you how easy it will be for the keyword to rank:

Ahrefs’ keyword difficulty is based solely on backlinks, and they only use the average number of referring domains within the top 10 ranking pages. The lower the number is, the lower the difficulty. You can read more about why Ahrefs doesn’t take more factors into account in their blog.

Look at the number of referring domains for “vegetarian pasta” in the screenshot below:

Note: The article with 0 backlinks is the featured snippet!

If you think this is an isolated case, play around with the tool and you’ll see plenty of examples like it. You’ll also see pages with more than 1,000 backlinks and pages with only 10 (the average is far from helpful).

For all of you who love Ahrefs – and use it as a go-to digital marketing tool for everything – we recommend being a bit wary.

SEMRush Keyword Difficulty

Level of trust: Medium

SEMRush shows keyword difficulty index, and their metric is calculated in percentages from 0 to 100%. However, the official scale provided by SEMRush divides the scores into three groups, with the actual scale falling between 60 and 80 percent. Here is a link to their article about their score.

I tried to get some additional information about the metric from SEMRush support. Here’s their response:

I highlighted the two most important things to consider: Analyzing the top 20 SERP results and using their own SEMRush Rank.

In case you don’t remember details for SEMRush rank, it’s calculated based on the estimated traffic that goes to a domain from all organic positions.

SEMRush shows whether SERP results are dominated by high authority domains with well-established organic rankings for multiple keywords. This helps to explain why – according to SEMRush – “vegetarian pasta” is a keyword with medium difficulty.

The metric is useful if you plan to launch a brand new website and need to look for niches that aren’t dominated by major high-authority players. The first step is getting a URL in the top 20 results which isn’t so valuable if you have a well-established domain that’s ready to attack the first page.

Moz Keyword Difficulty

Level of trust: High

MOZ’s keyword explorer is based on the page authority (PA) and domain authority (DA) of Google’s top 10 results. The metric also takes several other factors into account, like the number of internal pages vs. the number of home pages in SERP, as well as the use of query terms in the results. MOZ does not, however, reveal all factors.

In this article, Rank Fishkin explains the score and provides a sample scale:

MOZ’s PA and DA are still two of the most reliable SEO metrics and are based on a constantly-updated algorithm that’s based on more than 40 factors. You can read more about both of MOZ’s authority metrics here and decide for yourself, but many free keyword difficulty checkers and several other tools rely on Moz’s data.

The bad news? MOZ’s metrics are automatically calculated and the exact algorithms are not publicly available. That said, the formulas are updated regularly and utilize a wide variety of factors. When using the score, remember that the actual scale of the tool runs between 20 and 70 (not 0 to 100).

If you still have second thoughts, take a look at this research about the most accurate keyword difficulty tools.

Ubersuggest Keyword Difficulty

Level of trust: Medium

The free tool Ubersuggest has been recently revamped, but there isn’t a lot of publicly available information about their keyword difficulty score yet. The summary for the score is pretty short:

There are tons of questions surrounding Neil Patel’s release of a new version of the tool:

While Patel still hasn’t written the blog post article on the topic (as promised in the comments), his support team responded quickly. This was a positive surprise, as we didn’t have incredibly high expectations.

“Ubersuggest’s keyword difficulty is a proprietary metric that we developed specifically for Ubersuggest. [It uses] a complex algorithm to determine how hard it is for you to rank among the first 20 search results for a given keyword (in the context of a specific country) based on several different criteria on a scale from 0 to 100.”

To calculate this metric, Ubersuggest takes the following into account:

  • The Domain Score of each of the first 20 pages ranking for that keyword
  • How many backlinks these pages get
  • How in-depth and rich their content is

Sounds good, right? They use many ranking factors, similarly to MOZ. To determine a domain score, Ubersuggest incorporates the following information:

There are three downsides, however. First, this feature is relatively new, and we expect that the algorithm needs time, data, and fine-tuning for higher accuracy. The domain authority metric (another new feature) isn’t available for certain websites.

Second, the score is based on the first 20 results (similar to SEMRush) making it more useful for brand new websites.

Finally, the scale is still unclear. The tool shows low, medium, and high difficulty, but that’s not as convincing as other tools’ scales. We maintain that when enough data exists for the scale, Neil Patel will write the blog post he promised in the comments.

We plan to keep track of the metric as it’s definitely promising and has the potential to go from a medium to high level of trust. Don’t forget that the tool is free, which makes it the go-to option for small businesses or bloggers who simply don’t have the budget for MOZ or other paid tools. Keep in mind, however, that keywords with low difficulty scores may not be so easy to rank for.

 

Difficulty Comparison: What’s the Best Keyword Tool?

Comparison is always the best way to discover which tool can be trusted. Therefore, we randomly put together a small pool of about 50 keywords and compared the scores using the tools above to do a manual check-up of SERP results.

The manual score assigned in the spreadsheet is based on the analysis of key factors like content length and quality, interlinking, on-page optimization, and number of backlinks for the top-ranking pages.

I chose three topics: travel, digital marketing, and education. Of course, the test isn’t representative for all keywords and topics out there (if you have the time, perform this test for your niche). Still, I found it solid enough to assist in making a personal decision on the best tool to trust.

None of the tools matches my score 100%, but MOZ comes closest. I think it’s normal for the scores to vary (after all, every tool has a different formula), but it’s obvious that Ahrefs and Ubersuggest show nonrealistic scores. In some cases, they’re impossibly low (which can be very misleading). If you want to explore all the data, you can see it here.

 

How to Use the Keyword Difficulty Factor Wisely

Finding a trusted tool is the first important step in using the metric for your SEO analysis. The next step is to start using it like a pro.

Here are the pieces of advice that I wish somebody had given me when I was starting to work as an SEO:

1. Determine What “Low KW Difficulty” Means for Your Project

Looking for easy keywords can be totally different if you optimize a brand new service website or work on an e-commerce site that expands their product list. SERPs can also vary, depending on the topic and searcher’s intent. That has an effect on keyword difficulty, so it’s a great idea if you create a scale customized for your project.

If you’re working with an existing website, make sure to review which keywords it already ranks for and what their keyword difficulty is. Go after the easiest keywords only when you have close to zero organic traffic or launching a brand new website.

2. Plan Your Efforts Strategically

What’s the right time to use keyword difficulty when working on an SEO strategy? Easy keywords are harder to find, and the chances of being the only one optimizing for them is close to 0. Don’t get overwhelmed by the high scores you’ll start seeing and definitely don’t exclude topics at the start due simply because of keyword difficulty.

First, identify as many as possible keyword groups and topics with strong volumes that are relevant to the niche of your project. Very often, low difficulty jewels pop out of topics you never expected.

Once you’ve done the initial research and have examined several top competitors to determine the SEO specifics of the niche, use the metrics. Most importantly, review the overall tendency in the niche by using the scores as a comparative metric.

This is the moment when you’ll have to decide which keyword groups are worth the effort and which aren’t.

3. Don’t Forget to Go Back and Revise

In most cases, keyword research and analysis are used as a base for content strategies and production. Digital marketing is all about testing and seeing what works and what doesn’t, so don’t let the document rest in peace in your Gdrive folder.

After 6 months or a year, take the time to review which keywords you managed to get and which ones turned out to be harder than expected. Chances are, you’ll get a new perspective on the difficulty scale you created for the website and maybe be able to adjust the strategy.

 

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