Keyword Difficulty: How to Choose Keywords You Can Actually Rank For

Keyword difficulty is a metric used in SEO tools to estimate how competitive a keyword is — specifically, how hard it will be for a new page to rank in the top 10 search results. It is expressed as a score (typically 0–100), where higher scores indicate more competitive keywords requiring more authority and effort to rank for.

Understanding keyword difficulty is essential for realistic keyword selection. A small business website with low domain authority cannot compete for "SEO software" (KD 90) against Semrush, Ahrefs, and HubSpot. But it can rank for "SEO audit checklist for small business" (KD 18) within months of publishing quality content. Keyword difficulty guides you toward winnable keyword targets.

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How Keyword Difficulty Is Calculated

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Different SEO tools calculate keyword difficulty differently, but the primary inputs are:

Backlink profiles of ranking pages: The most influential factor. Keywords dominated by pages with thousands of high-quality backlinks require similar link authority to rank. Tools analyze the number of referring domains pointing to the current top-ranking pages and use this as the primary difficulty signal.

Domain authority of ranking sites: If the top 10 results for a keyword are all from high-authority domains (Wikipedia, Forbes, major brands), a lower-authority site faces an uphill competition regardless of content quality.

Content quality and comprehensiveness: Tools increasingly factor in how thoroughly the ranking pages cover the topic.

SERP features: Keywords with featured snippets, shopping ads, or video results have less standard organic real estate, effectively increasing competition for the remaining positions.

Important caveat: Difficulty scores are estimates, not guarantees. A KD 60 keyword might be achievable for a highly authoritative niche site with excellent content. A KD 30 keyword might be dominated by perfectly optimized pages that are difficult to displace despite the lower score. Difficulty scores are useful for comparative prioritization, not absolute ranking predictions.

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Interpreting Difficulty Scores

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Difficulty ranges are interpreted relative to your site's authority. The same score means different things for different domains:

KD 0–20 (Low): Achievable for most sites. New sites and sites with limited backlink profiles can rank within weeks to months with quality content.

KD 21–40 (Low-Medium): Achievable for sites with some authority (50+ referring domains) and good content. Ranking takes 2–6 months of patient optimization.

KD 41–60 (Medium): Competitive. Requires domain authority that comes from consistent link building. Sites with 200+ referring domains can compete, but content quality must be excellent.

KD 61–80 (High): Dominated by established, high-authority domains. Require significant authority (thousands of backlinks) and exceptional content. Long-term targets for growing sites.

KD 81–100 (Very High): Controlled by the most authoritative sites on the internet. Effectively unattainable for most small to medium-sized businesses without years of authority building.

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Checking Your Site's Authority Level

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Before using difficulty scores, establish your site's current authority baseline:

Ahrefs Domain Rating (DR): A composite backlink authority score on a 0–100 scale. Sites with DR 20 should target KD 0–20 keywords. Sites with DR 50 can target up to KD 40–50 keywords. Sites with DR 70+ can compete for KD 60+ keywords.

Moz Domain Authority (DA): Similar concept to DR. The same relative targeting logic applies.

Referring domains: The raw count of unique domains linking to your site is often more meaningful than composite scores. 50 referring domains from diverse, relevant sources represents meaningful authority; 1,000 links from 5 domains is less valuable.

Manual SERP assessment: Search your target keyword and examine what domains appear in positions 1–5. If they're all major national brands or highly specialized authority sites, your assessment of competition should override the tool's score. If several positions are held by smaller, similar-sized sites, the keyword may be more attainable than the KD suggests.

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Finding Winnable Keywords

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Keyword difficulty filtering is the primary tool for finding attainable opportunities:

Filter by difficulty in keyword tools:

In Ahrefs Keywords Explorer, set a KD maximum filter matching your site's authority level. In Semrush, use the keyword difficulty filter similarly. This filters out unrealistic targets and focuses research on achievable keywords.

Look for low-difficulty, adequate-volume combinations:

The sweet spot is keywords with KD within your authority range and search volume high enough to be worth targeting (typically 100+ monthly searches, depending on your niche). High-volume, low-difficulty keywords are rare — when you find them, prioritize them.

Target SERP weakness:

Some keywords have high-authority domains ranking for them, but the actual ranking pages are weak — thin content, low on-page optimization, few backlinks to the specific page (as opposed to the domain). Tools show page-level backlink data. A keyword with KD 50 where the #1 ranking page has only 5 backlinks presents an opportunity that the domain-level difficulty score masks.

New site strategy — target KD under 20:

New sites should exclusively target very low difficulty keywords for the first 6–12 months while building authority through content and link acquisition. Attempting high-difficulty keywords before establishing authority wastes content investment.

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Difficulty vs. Opportunity: The Full Picture

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Keyword difficulty is one input into keyword prioritization, not the only one. Evaluate keywords on all relevant dimensions:

Difficulty × Volume: The most common trade-off. High-volume keywords tend to be high-difficulty. Low-difficulty keywords tend to have lower volume. The optimal choice depends on your current authority and timeline.

Difficulty × Business relevance: A low-difficulty keyword that doesn't attract your target buyer is less valuable than a medium-difficulty keyword that brings in qualified leads. Don't optimize for ease at the expense of relevance.

Difficulty × Conversion potential: Transactional keywords with high conversion rates justify targeting despite higher difficulty. An informational keyword with high volume and low difficulty but low conversion potential may be less valuable than a commercial keyword.

Difficulty × Trend: An emerging keyword in a growing topic may currently have low difficulty but rising search volume. Targeting early — before the difficulty increases — captures the opportunity at lower competitive cost.

Blakfy evaluates keyword difficulty for every keyword in client research, building keyword strategies that balance attainability with business value — ensuring content investment goes to keywords that can realistically rank and drive qualified traffic.

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Frequently Asked Questions

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Are difficulty scores from different tools comparable?

No — Ahrefs KD, Semrush KD, and Moz KD use different calculation methodologies and don't produce equivalent scores. A keyword with KD 30 in Ahrefs might be KD 50 in Semrush. Each tool should be interpreted on its own scale. The relative comparison within a single tool (this keyword is easier than that one) is reliable; cross-tool absolute comparisons are not.

Can a low-authority site rank for a high-difficulty keyword?

Occasionally, yes. If you publish significantly more comprehensive, well-structured content than anything currently ranking, Google may rank it despite lower domain authority. This happens most reliably for keywords where current results are genuinely poor-quality. But this is an exception, not a strategy. Planning around low-difficulty keywords produces more predictable results than hoping to overcome authority gaps with content quality alone.

What's more important: high volume or low difficulty?

For new sites and sites with limited authority: low difficulty. Ranking for many low-volume keywords is more achievable and produces faster results than chasing high-volume competitive keywords. As authority grows, targeting higher-difficulty, higher-volume terms becomes realistic. The sequencing matters: build authority through low-difficulty wins, then expand to higher-competition terms.

How do I know if my keyword selection is causing ranking failures?

If you publish optimized content for keywords and still don't rank in the top 20 after 3–6 months, targeting keywords above your current authority level is the likely cause. Check the current top-ranking pages' domain ratings — if they're all 30–40 points higher than yours, the keywords are too competitive at your current authority level. Adjust down to lower-difficulty alternatives until authority grows.