Keyword difficulty: what it means and how to use it in your SEO strategy

What is keyword difficulty?

Keyword difficulty (KD) is a metric that estimates how hard it will be to rank on page one of Google for a given search term. Most SEO tools express it as a number from 0 to 100. A score of 5 suggests a phrase with little competition where a well-written page has a good chance of ranking. A score of 85 means the top results are dominated by high-authority sites with strong backlink profiles, and competing requires significant effort over a long period.

KD is useful as a filter. It helps you avoid spending months writing content for a keyword that your site has no realistic chance of ranking for at its current stage. But it is a blunt instrument. A single number cannot capture the full complexity of why a page does or does not rank. A low KD score does not guarantee a ranking, and a high KD score does not mean a keyword is permanently out of reach.

Most beginners treat KD as a binary signal: below 30 means easy, above 70 means impossible. The reality is more nuanced. A keyword with a KD of 60 might be entirely achievable for a site with solid domain authority and high-quality existing content. The same keyword is unrealistic for a brand new site. KD is a relative metric, not an absolute one, and it only makes sense when interpreted alongside your own site's current authority.

The practical guide to SEO keyword research at how to do SEO keyword research covers where KD fits within a full keyword research process. This article focuses specifically on how to read, compare, and act on KD scores from the tools you are likely using.

How different tools calculate KD (and why scores differ)

If you run the same keyword through Ahrefs and Semrush, you will get two different KD scores. This surprises people who assume there is an objective measure of difficulty. There is not. Each tool calculates difficulty using its own formula, weighted differently, based on its own data.

Ahrefs calculates KD based primarily on the number of referring domains pointing to the top ten ranking pages. It is a backlink-centric model. A keyword scores high in Ahrefs when the pages ranking for it have accumulated many links from many different websites. The score answers the question: how strong a backlink profile do you need to compete? Ahrefs also provides a separate "Traffic Potential" figure alongside KD, which is often more useful than volume alone, showing the estimated total traffic a page ranking for that keyword could capture across all related terms.

Semrush uses a broader set of signals in its Keyword Difficulty calculation, including backlink strength, content quality indicators, and SERP feature presence. It tends to produce higher scores than Ahrefs for the same keywords, which means a keyword that shows as KD 35 in Ahrefs might appear as KD 55 in Semrush. Neither is wrong. They are measuring slightly different things and weighting them differently.

Google Trends does not provide a KD score at all, but it remains a valuable companion tool. If a keyword is trending upward, its current KD score may understate future competition as more sites begin targeting it. Checking Google Trends alongside your KD data helps you spot rising topics before the competition catches up.

The practical implication of score differences is this: do not mix scores from different tools in the same spreadsheet without labelling their source. Comparing a KD of 40 from Ahrefs directly against a KD of 40 from Semrush is meaningless. Pick one tool as your primary KD reference and use it consistently so your scores remain comparable across your keyword list.

How to use keyword difficulty to choose targets

KD is most useful when you apply it relative to your own domain authority (DA) or domain rating (DR), depending on which tool you use. A site with a DR of 20 should not be targeting keywords where the top ten results all have DRs above 60. The gap is too large to close with content quality alone, no matter how good the article.

A rough framework for matching KD to site authority works as follows. New sites with minimal backlink profiles, typically DR below 20, should focus on keywords with KD scores below 20 in Ahrefs or below 30 in Semrush. Mid-authority sites with DR between 20 and 50 can target KD scores in the 20 to 50 range, with selectivity based on content quality. Established sites with DR above 50 can compete across most of the difficulty range, though targeting KD 80+ still requires exceptional content and a strong backlink strategy for that specific page.

KD is not the only factor in your targeting decision. Before committing to a keyword, check the actual SERP for that keyword and look at who ranks. If position one is held by Wikipedia, a major news outlet, or a government site, that keyword is harder to displace than the KD score suggests, regardless of the number. If position one is held by a mediocre blog post on a low-authority site, the keyword may be easier than the KD implies. SERP inspection takes thirty seconds and catches signals the KD metric misses.

Also check whether Google is showing a featured snippet for the keyword. Featured snippets appear above the standard results and can be won even without ranking first, but they also absorb a large share of clicks. If a snippet is present, factor in that the page ranking position one may not be the page receiving the most traffic.

The keyword research guide covers how to combine KD with search intent and volume to build a prioritised content list. KD alone tells you about competition. Intent tells you whether the traffic is worth attracting. Both matter before you assign a keyword to a content brief.

How to find low keyword difficulty opportunities

Low KD keywords are not always low-value keywords. Many of the most profitable search terms for small and medium businesses sit below KD 30 because they are specific, longer-form phrases that larger sites do not bother targeting. Finding them is a matter of knowing where to look.

In Ahrefs Keywords Explorer, use the KD filter to set a maximum of 20 and a minimum volume of 100. Add your seed keywords and run the search. Then apply the Questions filter to see which low-KD phrases are framed as questions. These question-based phrases often match featured snippet opportunities and are easier to create content around because the intent is explicit.

In Semrush's Keyword Magic Tool, use the difficulty filter to show only Easy or Very Easy keywords. Combine this with a volume filter to eliminate zero-volume phrases. Look at the related keywords tab, not just the exact match list. Related terms sometimes surface low-competition variants of your seed keyword that the main results miss.

Beyond the tools, three other sources reliably produce low-competition keyword opportunities. Google's autocomplete reveals what real searchers type after your seed term. The People Also Ask boxes in search results show question-format queries that frequently have lower competition than the head term they relate to. And competitor content gaps, found using the Content Gap or Keyword Gap tools in Ahrefs and Semrush, show phrases your competitors rank for where you have no content at all. Many of these gaps exist precisely because the keywords are too specific to attract much competition.

If your site needs quick wins while you build authority, the low-competition keywords guide goes deeper on how to identify and prioritise these opportunities across your specific topic area.

What this means for your keyword targeting

Keyword difficulty is a starting point, not a verdict. It tells you about the competitive landscape for a keyword at a point in time, based on a formula that approximates rather than precisely measures ranking difficulty. Used alongside SERP inspection, your own domain authority, and search intent analysis, it becomes a genuinely useful filter. Used in isolation, it produces either missed opportunities or wasted effort.

The most productive approach is to build a keyword list without any KD filter first, then apply the filter as a secondary sort. This avoids the mistake of never seeing high-value keywords because you filtered them out before evaluating them on other grounds. Some high-KD keywords are worth targeting on a long horizon even if they are not quick wins. Others with low KD are not worth targeting because the intent does not match your audience. KD is one input, not the decision.

For sites in the early stages of building organic traffic, low-KD keywords are the right place to start. They produce rankings faster, which builds domain authority, which makes higher-KD targets progressively more achievable. The strategy is cumulative. You are not abandoning competitive keywords permanently. You are sequencing your content plan so that each piece of content you publish improves your chances with the next one.

Check your KD targets every quarter against your actual rankings using Google Analytics. If a page you published for a KD 15 keyword is now ranking on page one and driving traffic, that is evidence your site is ready to move up the difficulty scale. If a KD 12 keyword has not produced a ranking after six months, the KD score missed something. Check the SERP again, look at the content quality of ranking pages, and decide whether to update the article or move on.

Keyword difficulty scores are more useful as comparative tools than as absolute ones. Whether a keyword is hard or easy depends on who you are competing against, and that context lives in the SERP, not in a number.