Keyword difficulty can come in a variety of metrics from various tools.
In some cases, keyword difficulty is synonymous with keyword competition or competitiveness.
Or, you may hear some SEO professionals in the industry simply refer to it as competition or competitiveness.
Probably the first company to actually use the term keyword difficulty (KD) was Moz within its own keyword research tool, Keyword Explorer.
Moz assigns a value from 1 to 100, where 100 is very difficult to rank for, and 1 would be very easy.
Moz does not share its specific proprietary formula on how it is computed, but the company does mention that it takes into account page authority (PA), domain authority (DA), and projected clickthrough rates (CTR).
PA and DA are also proprietary metrics by Moz that Google does not use.
These metrics are Moz’s attempt to assign a quality metric to serve as a proxy for Google’s PageRank score, which was once a public score Google gave to the public.
Moz uses known ranking factors that Google also evaluates to come up with these scores.
Moz has an API, and often, the keyword difficulty metric you see in other tools could be coming from Moz.
Some SEO pros prefer the Google Ads Keyword Planner Competition metric.
Google defines this value as the number of advertisers that showed on each keyword relative to all keywords across Google.
You will often see this expressed as a number with two decimal places between 0 and 1, where 1 is the most difficult to rank for, and 0 is the easiest.
It is important to note that this tool was intended for Google Ads users.
But the logic behind this metric is that keywords that are harder to rank for in pay-per-click (PPC) ads are also the keywords that are often also harder to rank for in organic search.
Similar to the competition metric of Keyword Planner mentioned above, Keyword Planner’s CPC Metric is primarily intended to be used by Google Ads advertisers.
Since CPC is the cost per click, it is also somewhat reflective of how competitive a keyword is organically.
The CPC metric you see will be the average CPC.
Some SEO pros may decide to use this because the more difficult it is to rank for a keyword, the higher the willingness to pay more to rank for it in PPC.
Since this is a cost, the values here are in dollar figures that can be a fraction of a dollar or slightly more than a dollar, ranging from a few cents to several dollars but typically staying below $10.
Many SEO professionals use the number of search results that appear when searching for a keyword in Google as a metric reflective of keyword difficulty.
The logic behind this is that the more results that appear for this keyword, the more we believe competitors are also trying to rank for it.
Some use specific search operators to fine-tune this number, such as the following operators:
The reason why some SEO pros would decide to use these search operators when determining a keyword difficulty metric is that often, SEO pros who are targeting a keyword phrase will include the keyword phrase in the title tag and within the URL.
However, aggregating this score for a large number of keywords requires some serious scraping of search results.
While some tools will just do those automatically, often, they will not be using any of the search operators.
Keyword difficulty is indeed important. Some may use it to determine which keywords to target and which keywords to disregard.
Most often, it should not be a metric that determines whether you target a keyword or not.
It is simply a metric that lets you know which keywords will be the easiest to rank quickly.
This can be helpful when strategizing which keywords to optimize first, especially if you are after some quick wins.