What Is Keyword Difficulty?
Definition
Keyword Difficulty (KD) is a metric used by SEO tools like Ahrefs, Semrush, and Moz to estimate how hard it would be to rank on the first page of Google for a given keyword. Scored 0-100, it is primarily based on the backlink profiles of the top-ranking pages.
How keyword difficulty is calculated
While each tool uses its own formula, the core logic is similar:
- Analyze top-ranking pages. The tool examines pages currently ranking in positions 1-10 for the keyword.
- Evaluate backlink profiles. The primary signal is the number and quality of backlinks pointing to those pages. More referring domains with higher domain authority means a higher KD score. You can check any site's DA for free.
- Estimate effort required. The tool calculates roughly how many backlinks you'd need to compete with those pages.
What the scores mean
| KD score | Difficulty | What it takes to rank |
|---|---|---|
| 0-10 | Very easy | Quality content alone may be enough |
| 11-30 | Easy | A handful of quality backlinks plus solid on-page SEO |
| 31-50 | Medium | Meaningful number of quality backlinks and strong content |
| 51-70 | Hard | Significant link building effort needed |
| 71-85 | Very hard | Hundreds of referring domains required |
| 86-100 | Extremely hard | Massive backlink profiles dominate (Wikipedia, major news outlets) |
What is the primary factor most SEO tools use to calculate keyword difficulty?
Correct! KD is primarily based on the backlink profiles of the pages currently ranking in the top 10 for that keyword.
Keyword difficulty is based on the backlink profiles of top-ranking pages. Search volume and CPC are useful metrics, but they don't determine how hard it is to rank.
KD and link building
There's a direct relationship between keyword difficulty and link building effort. A keyword with KD 70 means the top-ranking pages have strong backlink profiles, so you'll need to match or exceed that to compete. See our guide on how many backlinks you need for a practical breakdown by KD range.
Quality matters more than quantity. A few links from high-DR sites in your niche can be more effective than many low-quality links, especially for medium-difficulty keywords.
Limitations of keyword difficulty
- It's an estimate, not a guarantee. KD scores are based on third-party algorithms, not Google's actual ranking system.
- It mostly measures backlinks. Google uses hundreds of signals beyond backlinks, but KD typically doesn't account for content quality, user experience, or E-E-A-T.
- Scores differ between tools. The same keyword can have very different KD scores in Ahrefs vs. Semrush vs. Moz.
- It ignores your specific situation. A site with strong topical authority may rank for KD 60 keywords more easily than the score suggests.
A keyword has a KD score of 25. What does this typically mean?
Right! A KD of 25 falls in the "easy" range. A few quality backlinks alongside strong content should be enough to compete.
KD 25 is in the "easy" range. The top-ranking pages don't have strong backlink profiles, so a handful of quality links and solid content should suffice. KD measures difficulty, not volume.
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Start Getting Mentioned For $99/moFrequently asked questions
Is keyword difficulty the same across all SEO tools?
No. Each tool calculates KD differently. Ahrefs focuses on referring domains, Semrush includes content quality signals, and Moz uses Domain Authority. A keyword might be KD 45 in Ahrefs but KD 62 in Semrush. Always compare scores within the same tool.
Can I rank for high-difficulty keywords without backlinks?
It's extremely unlikely for KD 70+ keywords. For medium-difficulty keywords (KD 30-50), strong on-page SEO and topical authority can sometimes compensate for fewer backlinks, especially in less competitive niches.
Should I avoid all high-difficulty keywords?
Not necessarily. Target a mix: low-difficulty for quick wins, medium for steady growth, and high-difficulty as long-term goals. Building authority with easier keywords first makes it more realistic to compete for harder ones later.
How does keyword difficulty relate to link building?
Higher KD usually means more backlinks needed to rank. KD is primarily calculated from the backlink profiles of top-ranking pages, so link building is typically the most direct way to compete for higher-difficulty keywords.