Keyword difficulty (KD) is a 0–100 score that SEO tools use to estimate how hard it is to get a page into Google's top 10 results for a keyword. The higher the number, the stronger the pages you would have to beat, judged mostly by how many websites link to the pages already ranking. It is not a Google metric: Ahrefs, Semrush, Mangools and others each calculate their own, so the same keyword gets different scores in different tools.
For a new site, a KD under 20 in Ahrefs (or under 30 in Semrush, its "very easy" and "easy" bands) is a sensible first filter. Then look at the actual search results before you write, because KD only measures links. This guide shows how each tool calculates the score, what a KD number means in backlinks, and what to target at each stage of a site.
Key takeaways
- Keyword difficulty estimates how hard it is to reach Google's top 10 for a keyword (not position 1), on a 0–100 scale.
- Ahrefs KD is built only from referring domains to the top 10 pages, roughly 10 linking sites at KD 10, 56 at KD 40 and 202 at KD 70.
- Scores don't transfer between tools. Semrush adds Authority Score, dofollow ratios and SERP features; Mangools uses Moz and Majestic metrics.
- Of 183,540 keywords Outrank targeted for customer sites in the last 90 days, 63% had a KD under 20. The median was 14.
- KD ignores search intent, content quality and freshness. A five-minute look at the live results is what confirms a keyword is winnable.
What does keyword difficulty mean?
Keyword difficulty is an estimate of the effort needed to rank on the first page of Google for one specific search term. A low score means the pages on page one have few links and could be outranked by a newer site. A high score means page one is held by pages with strong link profiles, usually on strong domains.
In Ahrefs' own words, KD is "scored from 0 to 100 based on the backlink profiles of top-ranking pages." Their keyword difficulty guide translates the scale into plain terms:
- KD 0–5: the top-ranking pages barely have any backlinks.
- KD around 50: the top pages have a couple of hundred backlinks.
- KD 90+: the top pages have thousands of backlinks.
Two details change how you should read the number:
- It is about the top 10, not #1. Ahrefs says its KD "evaluates the chances of getting into top 10 of search results (not top 3 or top 1)." Mangools describes its score the same way. Reaching position 1 usually takes more than the score suggests.
- It is an average, not a forecast for your site. The score is the same for a brand-new blog and for a site with 400 articles on the topic. Your own authority and topical coverage decide what the number means for you.
How keyword difficulty is calculated
Every tool scouts the current top 10 for a keyword and boils their strength down to one number. What they measure differs:
| Tool | What goes into the score | How to read it |
|---|---|---|
| Ahrefs | Number of referring domains linking to the top 10 ranking pages. No on-page factors. | 0–100, nonlinear. Each value maps to an estimated number of referring domains (KD 40 ≈ 56). |
| Semrush | Median referring domains, median dofollow/nofollow ratio and median Authority Score of the ranking pages, plus SERP qualities of the keyword | 0–14 very easy, 15–29 easy, 30–49 possible, 50–69 difficult, 70–84 hard, 85–100 very hard |
| Mangools KWFinder | Link profile strength of first-page URLs from Moz DA/PA and Majestic Citation Flow/Trust Flow, weighted toward the weaker pages | 0–100; the "green zone" (easy) is 0–29 |
| Outrank free keyword tool | Difficulty from DataForSEO data | KD 35 or below with above-average volume is flagged as a "quick win" |
| Google Keyword Planner | "The number of advertisers that showed on each keyword relative to all keywords across Google" | Low / medium / high. An ads metric, not an SEO one |
Because the inputs differ, a keyword can be "easy" in one tool and "possible" in another. Pick one tool, learn what its numbers mean for your site, and compare keywords inside that tool only.
What a KD score means in backlinks
Ahrefs publishes the number of referring domains (unique linking websites) a page typically needs at each KD to reach the top 10. It is the most concrete way to read the score:
Referring domains needed to reach the top 10, by Ahrefs KD
Hover or tap the chart for exact values.
The curve explains why small KD differences matter at the top and hardly at all at the bottom. Moving from KD 10 to KD 20 adds about 12 linking sites. Moving from KD 80 to KD 90 adds about 400.
Compare the number with what your own pages have. If your best articles have five to ten referring domains each, keywords above KD 20 will be slow, whatever the content. If you are building links on purpose, our guide on how many backlinks you need to rank shows how to estimate the gap per keyword, and Domain Rating vs Domain Authority explains the domain-level scores these tools lean on.
Keyword difficulty vs SEO difficulty vs competition
Searchers mix up three terms, so here is how they relate:
- SEO difficulty and keyword difficulty are the same idea. Some tools say "SEO difficulty" to separate organic competition from paid competition. "Keyword ranking difficulty" also means the same thing.
- "Competition" in Google Keyword Planner is not keyword difficulty. It measures how many advertisers bid on the term. A keyword can be "high" competition for ads and easy to rank for organically, or the other way round.
- Personal keyword difficulty adjusts the score for your domain. Semrush's Personal Keyword Difficulty weighs the thematic relevance between your domain and the keyword, the competition within the topic, and your authority against the domains on the results page. It answers the question the general score can't: is this keyword hard for you?
What is a good keyword difficulty score?
A good KD is one your site can win today. There is no universal number, but these ranges are a solid starting point (our rules of thumb, using Ahrefs and Semrush scales):
| Your site | Ahrefs KD | Semrush KD% | Why |
|---|---|---|---|
| New: under 6 months, few referring domains | 0–20 | 0–29 | Page one needs fewer than about 22 linking sites. Content quality and intent match can win on their own. |
| Growing: a few dozen indexed articles, some referring domains | 10–35 | 15–49 | Topical coverage starts to count. Expect to need a handful of links to the best pages. |
| Established: hundreds of referring domains, deep topic coverage | 30–60+ | 30–69 | Pages need dozens of linking sites. Pick these for revenue keywords, not for every post. |
That is also roughly where automated keyword selection lands. Across the articles Outrank wrote for customer sites in the last 90 days, most targets sat at the low end of the scale:
Keyword difficulty of the keywords Outrank targets
KD 0–9
32.4%
KD 10–19
30.8%
KD 20–29
17.5%
KD 30–39
9.4%
KD 40–49
4.7%
KD 50–69
4.1%
KD 70+
1.1%
Low KD keywords also tend to be long-tail keywords with modest volume: the median keyword in the same data had 170 searches a month. That trade-off is the core of short-tail vs long-tail keyword strategy. Thirty winnable keywords at 170 searches beat one KD 70 keyword you never reach page one for.
How to check keyword difficulty
You don't need a paid tool to see a score:
- 1
Run your seed keyword through a free checker
Outrank's free keyword research tool shows volume, KD, CPC and a 12-month trend for related keywords with no signup. Ahrefs' free KD checker gives the score and the estimated referring domains for one keyword at a time. - 2
Filter by your KD ceiling
Apply the range for your site stage from the table above. Keep a separate list of higher-KD keywords that matter for revenue; they become link building targets later. - 3
Check the live results page
Search each shortlisted keyword in a private window. Note who ranks, how old the pages are, and what format Google shows (guides, product pages, videos, forums). - 4
Compare with your own pages
Look at how many referring domains your best existing pages have. If the top 10 pages have several times more, pick a narrower keyword or plan links for this page.
For the full process from seed list to content plan, follow the keyword research tutorial. To see how many people search a term before you check its difficulty, use our guide on how to check keyword search volume.
What keyword difficulty misses
KD is built from link data, so it is blind to most of what decides who ranks. Ahrefs lists the same blind spots in its own guide: it doesn't show whether the top pages satisfy the searcher, it can't see content freshness or thin "fluffy" pages, and it doesn't know your site.
Before you commit to a keyword, look for these signs on page one:
- Forum threads or Reddit posts in the top 5. Google found no good dedicated page. A focused article can often take that spot.
- Outdated pages. Results with old dates or screenshots of interfaces that no longer exist are easy to beat with a current answer.
- Low-authority sites ranking. If small sites already rank, the score is overstating the barrier.
- Intent you can't match. If page one is all product pages and you planned a guide (or the reverse), the KD doesn't matter: you are writing the wrong page.
- A crowded results page. AI Overviews, video carousels and "People also ask" boxes push organic results down, so a winnable keyword may still bring few clicks.
Our low competition keyword method turns these signs into a checklist you can run in five minutes per keyword.
Common keyword difficulty mistakes
- Comparing scores across tools. A 30 in Ahrefs and a 30 in Semrush are built from different data. Keep one tool as your reference.
- Treating KD 0 as free traffic. Many KD 0 keywords also have close to zero searches. Check volume and whether the term matches something you sell or know.
- Reading KD as your chance of ranking #1. It estimates a top 10 position. The top 3 usually takes more links and a better page.
- Writing one page per low-KD keyword. Many low-difficulty variations share the same results. Group them into one page with keyword clustering instead of publishing near-duplicates that compete with each other.
- Never rechecking. KD moves as ranking pages gain links or new competitors arrive. Recheck the keywords you planned months ago before writing.
Choosing between keywords that all pass the KD filter is a separate decision. Our guide on how to pick keywords covers that step with a simple scoring sheet. If you would rather not do this by hand, Outrank pulls live volume and difficulty for your niche and schedules one winnable keyword a day; the median KD it targeted in the last 90 days was 14.
FAQ
What does keyword difficulty mean in SEO?
Keyword difficulty is a 0–100 score that estimates how hard it is to get a page into Google's top 10 for a keyword. SEO tools calculate it mainly from the backlinks of the pages already ranking. A higher score means stronger competition and more links needed to reach page one.
What is a good keyword difficulty score?
For a new website, aim for KD under 20 in Ahrefs or under 30 in Semrush. Growing sites with some referring domains can move into the 20–40 range, and established sites can target higher scores for important keywords. Always confirm with a look at the live results, because KD ignores content quality and intent.
Is SEO difficulty the same as keyword difficulty?
Yes. "SEO difficulty", "keyword difficulty" and "keyword ranking difficulty" describe the same thing: how hard it is to rank organically for a term. It is different from the "competition" column in Google Keyword Planner, which measures how many advertisers bid on the keyword.
What does the keyword difficulty score tell you?
It tells you how strong the link profiles of the current top 10 pages are. In Ahrefs, each KD value maps to an estimated number of referring domains: about 22 at KD 20, 84 at KD 50 and 756 at KD 90. It does not tell you whether those pages satisfy the searcher, how fresh they are, or how strong your own site is.
Why do SEO tools show different keyword difficulty scores?
Each tool uses its own formula and its own link index. Ahrefs counts referring domains to the top 10, Semrush also weighs Authority Score, dofollow ratios and SERP features, and Mangools uses Moz and Majestic metrics. Compare keywords within one tool rather than across tools.
Can a new website rank for high-difficulty keywords?
Rarely at first. A KD 70 keyword in Ahrefs needs around 200 referring domains to reach the top 10, which a new site doesn't have. Start with low-KD long-tail keywords in your topic, build coverage and links, and move up the scale as your pages start ranking.
