GlossarySEO
What is keyword difficulty?
Also called: KD, keyword competition, SEO difficulty
Definition
Keyword difficulty (KD) is an SEO tool's estimate, usually on a 0 to 100 scale, of how hard it is to rank on the first page for a query. Each tool calculates it differently, mostly from the top results' backlinks.
Keyword difficulty, explained
Keyword difficulty isn't a Google metric. It's a third-party estimate, and every tool has its own formula. Ahrefs, for example, explains that its KD looks at how many referring domains the top ten ranking pages have, takes a weighted average with outliers removed, and plots it on a logarithmic 0 to 100 scale. It deliberately ignores on-page factors and estimates the chance of reaching the top ten, not the top spot.
Other tools mix in different signals, so the same query can score 20 in one tool and 45 in another. Compare difficulty only within one tool, and use it to sort a list, not to make final calls.
The most useful check is looking at the results page yourself. Who ranks? Big brands with deep link profiles, or small sites and forums? Do the top pages actually match the intent well, or is there an obvious gap? Is the page one full of features, ads and an AI Overview that leave little room for clicks? A "hard" keyword with a weak, outdated top ten can be easier than its score, and an "easy" one owned by a dominant brand can be harder.
For a new site, the rule of thumb is to start where both difficulty and competition look low and intent is commercial, then move up as your site earns links and trust. Your own domain's strength matters: the same query is easier for a site that already ranks for related terms.
Remember that difficulty scores are built mostly from backlinks. They say nothing about whether your page is better, which is the part you control.
Why it matters for founders
Difficulty scores help you skip queries a new site can't win yet. Read them alongside the actual results page, or you'll misjudge both easy and hard targets.
Example
Two queries both show KD 30. One's top ten is major SaaS brands; the other's is outdated forum posts. The founder targets the second and ranks within two months.
Common mistakes
- Comparing difficulty scores across different tools.
- Skipping the results page and trusting the number.
- Avoiding every high-KD query forever, even after the site grows.
Sources
Checked
Related terms
- Keyword researchKeyword research is finding the queries your potential customers type into search engines and AI assistants, estimating how often they're searched and how hard they are to rank for, and deciding which to target.
- Referring domainsReferring domains are the unique websites that link to your site. Ten links from one site count as one referring domain, which is why SEO tools treat referring domains as a better measure than total backlinks.
- Domain authority (DA and DR)Domain Authority (Moz) and Domain Rating (Ahrefs) are third-party scores, roughly 0 to 100, estimating the strength of a site's backlink profile. They are SEO tool metrics, not Google metrics, and Google doesn't use them.
- SERPA SERP (search engine results page) is the page a search engine shows after a query: the list of links plus features like AI Overviews, featured snippets, videos, ads and "People also ask" boxes.