Keyword difficulty is a score, usually on a scale of 0 to 100, that SEO tools give a search term to estimate how hard it would be to reach the first page of Google for it. It is a third-party estimate, not a number Google calculates or publishes.
How keyword difficulty works
Each tool builds its score from its own data. Ahrefs, for example, bases its figure mainly on how many separate websites link to the pages currently ranking in the top ten. Semrush combines several factors, including the strength of the ranking domains and their links. Other tools use other recipes. Because the inputs differ, one keyword can score in the teens in one tool and the high thirties in another. Neither is a mistake; they are measuring slightly different things. The comparison of Ahrefs and Semrush explains where their data comes from.
Most difficulty scores lean heavily on links, specifically the number of referring domains pointing at the pages that already rank. They say little about whether those pages actually answer the query well, whether Google shows a map pack above the organic results, or whether the results are dominated by directories and marketplaces.
A common mix-up is the “Competition” column in Google’s Keyword Planner. That measures how many advertisers bid on the term in Google Ads. It tells you nothing about how hard the term is to rank for organically.
Why it matters
Difficulty helps you decide where to spend limited time. A new bookkeeping practice in Bristol is unlikely to rank for “accountant” across the UK in its first year, whatever it publishes. It has a far better chance with specific terms such as “bookkeeping for landlords Bristol” or “Making Tax Digital help for sole traders”. Choosing achievable terms early builds visibility, enquiries and links that make harder terms reachable later.
The score is also relative. A difficulty of 40 means something very different to an established national brand than to a site launched last month. Check that you are using the United Kingdom database too: tools hold separate figures by country, and a US score can be misleading for a UK term.
For local searches the number can mislead in another way. Tools calculate difficulty from the organic listings, so “emergency plumber Leeds” might look easy while the real competition sits in the map pack, which is won through Google Business Profile, reviews and proximity rather than links.
Common mistakes
- Comparing scores from different tools as if they were on the same scale.
- Ignoring your own site’s strength when reading the number.
- Ruling out a core commercial term because it scores high, rather than planning a route towards it.
- Chasing easy terms that no buyer would ever search.
- Leaving the tool set to the US or “all countries”.
- Taking the score on trust without looking at the results page itself.
How to act on it
Use difficulty to sort a shortlist, then make the real judgement by looking at the results. A quick SERP analysis shows who ranks, whether they are national brands, local competitors, directories such as Checkatrade or Yell, or forums, and how well their pages answer the query. If the top results are thin or off-target, the term may be easier than its score suggests. If every result is a household name with a dedicated page, it is probably harder.
Then plan in stages. Start with specific, lower-competition terms, often long-tail keywords with clear buying intent, and build supporting content and links towards the broader terms you ultimately want. Weighing difficulty against intent and commercial value is the core of the keyword research work I do before any content is planned.