What is keyword difficulty?

Keyword difficulty is a number between 0 and 100 that estimates how hard it will be for a new page to rank in the top 10 Google results for a specific search term. A score of 5 means almost anyone can rank for the keyword. A score of 80 means the top 10 is dominated by high-authority sites and outranking them is expensive.

The score is derived from the pages already ranking for the keyword. Tools look at how many other websites link to those pages, how strong those linking sites are, and how authoritative the ranking domains are overall. A keyword where the top 10 is mostly Wikipedia, Forbes, and HubSpot will score much higher than a keyword where the top 10 is small blogs and forum threads.

In practice the score is easiest to understand with real examples. "What is keyword difficulty" has a difficulty of 5 and gets 260 searches per month in the US. A brand-new site with a few well-written articles can rank for it. "Content marketing strategy" has a difficulty of 77 and you are competing with Semrush, HubSpot, and the Content Marketing Institute. A new site will not rank for the second one within its first year no matter how good the article is.

Different SEO tools produce different scores for the same keyword because they weight backlinks, domain authority, and content signals differently. A keyword that scores 30 in Ahrefs might score 45 in Semrush. What matters is consistency within one tool: use the score to compare keywords against each other, not as a universal truth.