How Ahrefs keyword difficulty score actually works

Executive overview

Many users expect keyword difficulty (KD) to be a magic ranking predictor. It isn't. KD is a proxy for the average number of linking websites among the top 10 results for a keyword.

Outliers skew the average, so treat KD as a filter for narrowing large keyword lists — not as a final ranking decision. Always review the actual top 10 pages before committing to a keyword.

KD tells you how many backlinks you'll likely need to rank on page one — not whether you'll rank.

How KD is calculated

• KD = average referring domains across the top 10 results for a keyword
• Non-linear scale: KD 10 requires ~10 referring domains; KD 70 requires ~202; KD 90 requires ~756
• Outliers in the top 10 skew the average — a few high-authority pages inflate the number
• The tilde (~) in the hint is intentional: it's an approximation, not a guarantee

KD difficulty ranges

• Below 10: easy — almost anyone can acquire links from up to 10 sites
• 10–30: medium — getting up to 36 referring domains is a real challenge
• 30–70: hard
• 70+: super hard — only a few sites can generate that volume of backlinks

How to find your realistic KD ceiling

• Open Ahrefs Site Explorer and enter your blog URL
• Go to the "Best by links" report to see referring domains on your top articles
• Your highest-performing articles define the upper bound of KD you can realistically target
• Example: Ahrefs' own best articles have 100–350 referring domains, so they target up to KD 80