Keyword Difficulty.

Keyword Difficulty (KD) is a score—typically 0–100—that estimates the competitive difficulty of ranking for a given keyword in organic search. It is calculated differently by each tool: Ahrefs weights the backlink profiles of the top-ranking pages; SEMrush considers a broader set of ranking signals; Moz uses its own domain and page authority metrics. Higher scores indicate more competitive SERPs dominated by authoritative pages.

Using KD Strategically

Keyword difficulty should be interpreted relative to your own domain authority. A KD of 40 might be achievable for a site with DR 60 but out of reach for a new site with DR 5. When building an SEO programme, prioritising lower-KD keywords that align with business intent provides quick wins that build authority, enabling you to target higher-difficulty keywords over time.

KD Limitations

KD scores are approximations, not guarantees. A low-KD keyword may still be difficult to rank for if it triggers SERP features (People Also Ask, AI Overviews) that capture most clicks. Analysing the actual SERP—who is ranking, why they rank, what content exists—is more reliable than relying on a single number.