If you’ve ever done keyword research or looked at an SEO report, you’ve probably seen a number labelled “keyword difficulty” or “KD score” sitting next to a search term. It’s one of the most useful metrics in SEO, and one of the most misunderstood. This guide explains what it means, how it’s calculated, and how it should actually influence the keywords you go after.
What Is Keyword Difficulty?
Keyword difficulty is an SEO metric that estimates how hard it would be to rank on the first page of Google for a specific search term. It’s usually shown as a score from 0 to 100. The higher the score, the more competitive the keyword and the harder it is to earn a top-10 position in organic search results.
A score of 5 means very few established pages are competing for that term. A score of 80 means you’re up against high-authority websites with strong backlink profiles, and breaking onto page one without significant domain strength and content investment is unlikely.
Most keyword research tools, including SEMrush, Ahrefs, and Moz, include a keyword difficulty score as a standard metric. The exact methodology varies between tools, which is why the same keyword can show a KD of 35 in one platform and 58 in another. More on that shortly.
Keyword Difficulty vs Keyword Competition: What’s the Difference?
These two terms are often used interchangeably, but they measure different things. Keyword difficulty refers to organic search results, specifically how hard it is to rank without paying for placement. Keyword competition, on the other hand, is a metric used in tools like Google Keyword Planner and relates to paid search (PPC), not organic rankings.
If you’re planning your SEO content strategy, keyword difficulty is the number you want. Keyword competition tells you how many advertisers are bidding on a term, which is useful for paid campaigns but doesn’t tell you anything about how hard it is to earn a free organic position.
How Is Keyword Difficulty Calculated?
There’s no universal formula. Each SEO tool uses its own proprietary methodology, which is why scores aren’t directly comparable across platforms. That said, most tools look at a combination of the following factors when calculating a keyword difficulty score.
Backlink Profiles of Top-Ranking Pages
The number and quality of backlinks pointing to the pages currently ranking for a keyword is the single biggest factor in most difficulty calculations. If the top 10 results all have hundreds of referring domains from high-authority sites, the keyword will score high. Ahrefs, for example, weights its KD score heavily towards the backlink profiles of the top-ranking pages.
Domain Authority of Ranking Sites
If the first page of Google for a keyword is dominated by large national brands, news publishers, or Wikipedia, the keyword difficulty will be high regardless of how well-optimised a smaller site’s page might be. Domain authority, a measure of a site’s overall link equity and trustworthiness, plays a significant role in how tools estimate difficulty.
Search Volume
Higher search volume tends to attract more competition, which pushes difficulty scores up. A keyword that 50,000 people search for each month is naturally going to attract more pages competing for it than one with 200 monthly searches. Search volume and keyword difficulty often move in the same direction, though there are exceptions, particularly with long-tail keywords.
SERP Features
When a keyword triggers features like featured snippets, local packs, People Also Ask boxes, or Google Shopping results, those features take up prominent space in the results, pushing standard organic listings further down the page. Tools factor this in because even a top-10 ranking may generate fewer clicks when SERP features dominate the page.
What’s a Good Keyword Difficulty Score to Target?
This is entirely relative to your site’s current authority, not an absolute number. A score of 40 might be very achievable for a site that’s been building backlinks and topical authority for years, and completely out of reach for a brand-new domain.
As a general guide:
- 0 to 20: Low difficulty. Achievable for most sites, including newer ones. These are often long-tail keywords with lower search volumes but strong conversion potential.
- 21 to 40: Moderate difficulty. Realistic for established sites with some domain authority. Good content depth and a solid internal linking structure can get you there.
- 41 to 60: Competitive. You’ll need meaningful domain authority, quality backlinks, and genuinely useful content to rank here.
- 61 and above: High difficulty. These keywords are dominated by large, well-established sites. Achievable eventually, but not a realistic near-term target for most SMEs.
The sweet spot for most small and medium-sized businesses is finding keywords with a difficulty score under 30, paired with a search volume that justifies the effort. That combination gives you a realistic path to page-one rankings while you build authority for harder targets over time.
It’s also worth remembering that keyword difficulty scores are estimates, not guarantees. A KD of 25 doesn’t mean you’ll rank automatically. A poorly written, thin page with no internal links can still fail to rank for a low-difficulty keyword. The score tells you about the competition, not about the quality of your own content.
Why Keyword Difficulty Varies Between Tools
If you’ve checked the same keyword in SEMrush and Ahrefs and seen very different scores, you’re not doing anything wrong. Each platform uses its own algorithm, its own database of backlink data, and its own weighting of the various factors involved. SEMrush, for instance, also factors in SERP features and search intent signals, whereas Ahrefs places a heavier emphasis on the number of referring domains pointing to the top-ranking pages.
The practical implication is simple: use one tool consistently. If you build your keyword strategy using SEMrush scores, compare everything in SEMrush. Switching between tools mid-research leads to false comparisons and poor prioritisation decisions.
How Keyword Difficulty Fits Into a Broader SEO Strategy
Keyword difficulty is most useful when you look at it alongside search volume and search intent, not in isolation. A low-difficulty keyword with no search volume isn’t worth targeting. A high-volume keyword with a difficulty score your site can’t compete with is a waste of time and resource. The real skill in keyword research is finding the intersection: terms that enough people are searching for, that your site has a realistic chance of ranking for, and that match what a potential customer is actually looking for.
At Yellow Circle, when we build SEO strategies for clients, keyword difficulty is one of the first filters we apply. We use it to separate the realistic opportunities from the wishful thinking, and to build a content plan that generates genuine traction rather than months of effort on terms a site isn’t ready to compete for. That approach is especially important for SMEs, where time and budget are finite and every piece of content needs to earn its place.
If you’re new to keyword research, it helps to start with a topic cluster approach: target a mix of low-difficulty, long-tail keywords alongside your core commercial terms. The long-tail content builds topical authority, which gradually improves your chances of ranking for the more competitive terms later on. You can read more about how we approach this in our guide to SEO for UK businesses.
Keyword Difficulty FAQs
What is a good keyword difficulty score for a small business?
For most small businesses, targeting keywords with a difficulty score of 30 or below is a sensible starting point. These terms are achievable without an enormous backlink profile, and they often include specific, long-tail phrases that attract highly relevant traffic. As your site builds authority over time through quality content and backlinks, you can gradually target more competitive terms. The goal isn’t to avoid difficulty entirely; it’s to match your ambition to your current site strength and expand from there.
Does keyword difficulty change over time?
Yes. Keyword difficulty scores are not fixed. They shift as new pages enter the rankings, as existing pages gain or lose backlinks, and as Google updates its algorithm. A keyword that was relatively easy to rank for two years ago might be more competitive today if a large brand has entered the space. Equally, some keywords become less competitive over time. It’s worth reviewing your target keywords periodically rather than treating the scores you captured during initial research as permanent.
Is keyword difficulty the same in every country?
No, and this matters particularly for UK businesses. The competitive landscape for a keyword in the UK can be quite different from the same term in the US. Fewer established UK-based sites competing for a term can mean lower difficulty scores in a UK database compared to a global or US database. Always set your keyword research tool to the UK when doing research for a UK audience. Most tools, including SEMrush, allow you to filter by country so your data reflects the actual competition you’re facing.
Should I only target low-difficulty keywords?
Not exclusively. A content strategy built only on low-difficulty keywords will miss out on the commercial terms that drive the most valuable traffic. The right approach is a mix: low-difficulty, long-tail content to build topical authority and generate early traction, alongside a longer-term plan to compete for higher-difficulty terms as your domain authority grows. Avoiding hard keywords altogether keeps you off the terms your competitors are winning, which limits how far your SEO can take you.
Understanding Keyword Difficulty Is Just the Start
Knowing what a keyword difficulty score means is useful. Knowing how to apply it, alongside search volume, search intent, and your own site’s authority, is what separates a keyword list from an actual SEO strategy.
If you’d like to understand how your site stacks up against the keywords that matter for your business, our team is happy to take a look. Find out more about how Yellow Circle approaches SEO, or get in touch to start the conversation.
