What Is Keyword Difficulty (KD)?

A 0–100 estimate of how hard it is to rank on page 1 for a keyword, based on the authority of current rankings.

Keyword Difficulty (KD) is a 0–100 score estimating how hard it is to reach page 1 of Google for a specific keyword. A KD of 5 is a quick win; a KD of 90 is a battle against established authorities.

Providers (Moz, Ahrefs, Semrush) compute KD from the authority of the domains currently ranking — typically their backlink strength. The logic: if page 1 is full of strong domains, you need serious authority to displace them.

KD is a directional guide, not a law. A high-KD head term may still be winnable with a definitional page if the current results are weak, outdated, or generic. A low-KD term can still be hard in a narrow niche where the top-10 pages are perfectly relevant. Always cross-check KD with an actual look at the SERP before committing.

As a rule of thumb, new sites should lean toward KD under 40; established domains can push higher. Allable surfaces KD next to volume so prioritization happens in one view.

Examples

• KD 5 long-tail: "what is impression share" (140/mo, KD 4) — a definition page can rank with almost no authority.
• KD 85 head term: "backlink" (5,400/mo, KD 97) — not the target; "what is a backlink" (3,600, KD 70) is still hard but definitional intent changes the game.