What is keyword difficulty and what does it mean for SEO?

What is keyword difficulty?

Keyword difficulty (KD) measures how difficult it is to rank on the first page of Google for a specific keyword. Every keyword has a unique difficulty score calculated differently by various tools. 

KD is typically calculated as a percentage, with 0 being the easiest to rank for and 100 being the hardest.

When it comes to search engine optimization (SEO), KD cannot be used as a precise metric. Instead, use it to understand how stiff the competition is for a keyword. 

There are different ways of calculating keyword difficulty percentage (KD%). In fact, all major SEO tools use distinct formulas that rarely come to the same conclusions about a keyword. Getting to know these formulas is the first step to understanding and properly using KD% in your SEO strategy.

How to calculate keyword difficulty

Instead of discussing every single keyword difficulty formula, we have focused on the formulas used by these three popular SEO tools: Semrush, Ahrefs and Moz.

Semrush keyword difficulty calculation 

Semrush has the most complicated and robust formula of the three tools. They consider the domains presently on the first page of Google, the types of results a keyword shows and the region in which the keyword is being searched.

Domains are measured by the number of backlinks (nofollow and dofollow with different weights) and their domain authority scores. Semrush also tracks what kind of search results Google displays for the keyword, so if a keyword has rich results, then it may be harder to rank for it. Another criterion is the region since smaller countries tend to have less competition due to the lower population.

Ahrefs keyword difficulty calculation 

Ahrefs has the simplest KD% formula out of the three tools discussed in this post. They simply check the domains on the first page of search engine results for a particular keyword, then look at the number of backlinks each of these domains has. If the domains have many backlinks, then the KD% will be higher. If they have very only a few, then the KD% will be lower.

Having this simple approach to SEO keyword difficulty has advantages. For example, it makes it easier to understand who your competition is and where your website stands against it.

This approach also has drawbacks since it oversimplifies some of Google’s ranking factors. The KD% might be inaccurate because sites with few backlinks can also put up very tough SEO competition.

Moz keyword difficulty calculation 

Moz is a little less transparent about its keyword difficulty formula. What we do know is that they consider the domain authority and page authority of all the pages on the first page of search results. 

They also take into account projected click-through rates (CTR) for all of these pages and give more visible (higher position) pages more weight. Moz then averages all of these numbers for all ten sites on the first page to come up with a keyword difficulty percentage. 

More complex formulas like those from Moz and Semrush have the advantage of including more ranking factors and giving users a better idea of their competition. However, since these factors are not a replica of Google’s own algorithm, they are still likely inaccurate. 

How does domain/page authority impact keyword difficulty?

Depending on what tool you are using, domain and page authority can have a huge or negligible impact on keyword difficulty. Moz and Semrush take domain/page authority into account when calculating keyword difficulty. Both tools look at the average authority scores of the top ten search results. 

To fully understand how authority scores impact difficulty calculations, you need to know how these different tools calculate authority scores. These scores are meant to represent a website or page’s overall quality and SEO performance and can only be used to compare websites, not as an absolute judgment.

Both Semrush and Moz calculate page authority differently.

Semrush domain authority calculation

Semrush uses its crawler to understand and track the organic performance of a website, including its rankings and traffic data. This crawl gives them an initial idea of the site’s authority. Then Semrush uses its backlink algorithm to check what kind of backlinks a site has.

Here are the metrics considered in coming up with an authority score:

  1. Number of backlinks 
  2. The authority score of these backlinking sites 
  3. Number of outbound links 
  4. Number of nofollow/dofollow outbound and inbound links 
  5. Number of IPs and subnets pointing to the site 

Moz domain authority calculation

Moz also looks at a website’s backlink profile to determine authority, but it also considers unique metrics such as spam score (how much duplicate content is on the site) and SEO performance. The exact formula is not public knowledge but it’s known that link profiles play a huge part in the calculation.

How to find low difficulty keywords with high volumes?

When optimizing a page for SEO, you should always have a list of target keywords in mind. To find keywords for this list, you should be looking for keywords with sizable volume and low difficulty, so you can realistically rank for them. Finding these keywords can be tricky since not every niche will have them, but there is a way to speed up the keyword research process

There is no guarantee that these keywords will even exist for your particular niche, but it is definitely worth checking. Keywords that are relatively easy to rank for and have the potential to bring traffic are the kind of quick wins that should start an SEO project. 

Below are some ways to find these keywords:

Long tail keywords

Suppose you are looking for keywords around a specific topic but all the obvious keywords seem to have very high difficulties. In that case, you should look into keywords with modifiers or more specific requirements.

For example, say you are looking into call center management as a topic and you keep finding keywords like “call center performance”, which has a sizable volume but a Semrush keyword difficulty of 52%. This KD% may not be very high but it is likely out of reach for new websites. You can instead optimize for keywords such as “call center agent performance” or “call center performance management”, bringing down the KD to just 27 but keeping some volume.

A great place to find long tail keywords (if you have no proper SEO tools) is the bottom of the search page in the related searches section, as shown below:

Long tail keywords in related searches example

You can find many highly relevant long tail keywords in the related searches section.

If you have access to an SEO tool, try using the keyword suggestions function (Keyword Magic tool for Semrush) and sort by KD%. Keywords everywhere is a good free tool to find more long-term keywords every time you search for your topic.

Competitor research

Why do any research when your competitors have already done the work? Simply run a quick scan of your competitor’s rankings and hunt down the ones with the highest potential. All you need for this is an SEO tool capable of running a scan on a domain to see what keywords it is ranking for.

Once you have your tool set up and your competitor’s rankings in a sheet, sort by difficulty and find relevant keywords with high volume. You may have to do this with a few competitors before you have enough high-value keywords.

Should you ignore high-difficulty keywords?

Trying to rank for high-difficulty keywords can feel pointless but it doesn’t mean you should ignore them entirely. A strong keyword list is made up of several low-difficulty keywords and a few relevant high-difficulty ones. Your content strategy should take into account your entire keyword list.

Do remember that Google doesn’t actually use keyword difficulty as a metric. It just wants to give users the most helpful results for their queries. If your content/page is specially built to answer a high-difficulty keyword and manages to accrue some backlinks, you could very well rank for said keyword.

You will still have to manage your expectations. Just because you write killer copy and create detailed graphics, it does not mean you will rank for a high-difficulty keyword. The important part here is to at least try for a few of them. A high KD%, in this case, could be anywhere from 70 to 100.

What are the best keyword difficulty tools?

Our top recommendations for keyword research tools include:

  1. Moz (Paid)
  2. Ahrefs (Paid)
  3. Semrush (Paid)
  4. Keywords Everywhere (Free)
  5. Long Tail Pro (Paid)
  6. Google Keyword Tool (Free)

Another tool that you should notice is the Google Keyword Planner. Though it has very few options, it is a great way to find keywords with decent volumes. You can even use the cost per click (CPC) rating each keyword gets as a measure of competition, but it will be much less accurate than most other tools. 

When using CPC, note that many high-competition keywords will have low CPCs since they are unlikely to generate revenue directly. Just because fewer people are willing to pay money for a keyword, it does not mean people are not organically competing for it.

How to check keyword difficulty on Semrush, Ahrefs and Moz


Checking keyword difficulty on Semrush is as simple as entering your keyword or list of keywords into the keyword overview tab. Semrush will give you several vital statistics regarding the keywords, including the monthly search volume, cost per click and even search intent.

Semrush keyword difficulty tool example

This keyword difficulty data can be exported to Excel for easier analysis.


Ahrefs has built a special keyword difficulty checker that you can use to check the KD% of a keyword. You can use a limited version of this tool for free or pay for the full version. With the limited version, Ahrefs will show the statistics for the domains in the top 3 positions. These stats include authority, backlinks, traffic and the number of keywords the domain is ranking for. The paid version will allow you to see the stats for all ten domains on the first page of search results.

Ahrefs keyword difficulty tool example

Ahrefs gives you an excellent SERP analysis for a keyword.


Moz has a well-built keyword explorer tool that will allow you to analyze keywords in bulk, if you use a paid account, or just a few a day if you use a free account. The tool will give you keyword difficulty, search volume, organic click-through rate (CTR) and even a custom priority score to help you prioritize your keywords.

Moz keyword difficulty tool example

Moz will also show you some proprietary metrics that may be useful when planning a large keyword list.

Building a keyword list for better SEO results

Planning your B2B website’s keyword list does not have to be a complicated task. If you need any help, get in touch with our team of experienced SEO specialists.


What is a good KW difficulty?

Ideally, your keyword difficulty scores are as low as possible, so you have an easier time ranking. However,  this is unlikely to happen. So here’s what we recommend: 

  • If you are running a new site with low authority, try to keep your SEO difficulty scores below 50. 
  • If you are running an older site that has gained authority, target keywords of difficulties up to 75 or 80. However, most of your list should always include low difficulty keywords, regardless of your site authority.

Is higher keyword difficulty good?

Higher keyword difficulty implies that very strong domains are competing for the same keyword. Likely, it’s a profitable or at the very least useful keyword. 

A good strategy is to use keyword difficulty as an indicator for valuable lead-generating keywords. But take into account that tools that calculate KD% are not always correct and low competition does not mean a keyword is not useful. If you only go after high-difficulty keywords, you may lose out on some very advantageous quick wins.

What is a keyword analysis tool?

A keyword analysis tool is a special SEO software that looks at various metrics for a particular keyword. These tools help users find new keywords to rank for. Below are some of the useful metrics that these tools can provide:

  1. Keyword search volume
  2. Keyword difficulty percentage
  3. Priority
  4. Cost per click (on Google Adwords)
  5. Searcher intent
  6. Average click-through rate
  7. SERP features (what rich results appear for the keyword) 

What is SEO difficulty score?

SEO difficulty score is simply a roundabout way of saying keyword difficulty score. They both mean essentially the same thing: how hard it is to rank for a particular keyword.

Momin Shahab

Momin Shahab

Momin Shahab is an SEO consultant at Productive Shop. He has worked in SEO on an international level for upwards of three years at various companies. He has gained training in content marketing, project management and data analysis. When he's not working or researching SEO, he is reading and collecting books.

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