The keyword difficulty tool is designed to show you how difficult it would be to rank organically for a keyword. Enter a list of up to 100 keywords into the tool at a time and SEMrush calculates a difficulty percentage for each keyword.
This percentage is based on a scale of 1 to 100. The higher the difficulty percentage, the more competitive that keyword is, and the harder it would be to outrank the current pages on the first page. This data is based on the competition between domains that are ranking for the requested keywords in Google’s top 100 organic search results.