KD & Volume
Every keyword research tool gives you two numbers before anything else: search volume and keyword difficulty. Most beginners read volume first and difficulty second. The better approach is the reverse - because difficulty determines whether a number is opportunity or noise.
What search volume actually is
Search volume is the average number of times a keyword is searched per month. A keyword with 10,000 monthly searches has a larger potential audience than one with 100. That much is straightforward.
What it does not tell you is how many of those searches result in a click to your site, or any site. AI Overviews, featured snippets, People Also Ask boxes, and other SERP features absorb a growing share of informational queries without any organic click. A keyword with 10,000 monthly searches might deliver a few hundred actual clicks to first-page results. Your share of those clicks - if you rank at all - depends on your position.
Volume is also an estimate, not a measured fact. Every tool calculates it differently using different data sources and methodologies. Ahrefs and Semrush will often show different volume figures for the same keyword. Neither is definitively correct. Use volume as a signal of relative demand - a keyword showing 5,000 searches likely has more demand than one showing 50 - but do not treat the numbers as precise.
What keyword difficulty actually measures
Keyword difficulty (KD) is an estimate of how hard it would be to rank on the first page of Google for a given keyword. Most tools score it on a scale of 0 to 100. The score is primarily driven by the backlink profiles of pages currently ranking in the top 10 - if those pages have hundreds of referring domains from authoritative sites, the score will be high.
Research shows a consistent relationship between volume and difficulty. Keywords with more than 100,000 monthly searches typically carry a difficulty score of around 76%, while lower-volume keywords average closer to 39%, according to data analysed by Writesonic. More searches means more competition means higher difficulty - almost without exception at the high end.
The critical limitation: KD scores do not account for your site specifically. A score of 45 is not "medium difficulty" in the abstract - it is medium difficulty for a site with a certain level of authority and backlink profile. A score of 45 on a brand-new site with no backlinks is functionally impossible. The same score on a domain with established authority and 300 referring domains may be achievable within months. Always read KD relative to your own site's current strength, not as an absolute.
Why targeting high-volume keywords first is usually the wrong move
The most common keyword research mistake is building a target list dominated by high-volume, high-difficulty terms and wondering why nothing ranks. Backlinko's research found that only 0.63% of users click on page-two results. If you cannot reach page one, the volume of a keyword is irrelevant - you receive none of it.
New sites and sites with limited authority need to target keywords where they can actually reach page one. That means starting with low-to-medium KD keywords where the competing pages are beatable - not necessarily because they are poor content, but because they have fewer and weaker backlinks. Building a track record of ranking for achievable keywords earns your site the authority needed to compete for harder ones over time.
How to read KD and volume together
The most useful frame is not "high volume" or "low difficulty" in isolation - it is the ratio between them relative to your site.
A keyword with 200 monthly searches and a KD of 8 may deliver more traffic than one with 5,000 searches and a KD of 72 - because the first is genuinely rankable for you right now, and the second is not. The question is not which keyword is bigger. It is which keywords you can actually win, and what traffic winning them would deliver.
Filtering by difficulty first is the practical approach. In Ahrefs or Semrush, set a KD upper limit that matches your site's current authority - often KD 20 to 30 for newer sites, KD 40 to 50 for more established ones. Then sort the resulting keyword list by volume to find the highest-demand opportunities within your reach. This keeps the search anchored in reality rather than aspiration.
The SERP check that overrides the score
KD scores are useful as a filter, not as a final decision. Before committing to any keyword, run the actual SERP and look at what is ranking. Ask:
- Are the top results from major authoritative domains, or are smaller sites ranking?
- Do the ranking pages have strong backlink profiles, or thin ones?
- Is the content on page one genuinely comprehensive, or is there an obvious gap you could fill?
A KD score of 35 with all top-10 results from high-authority domains and thousands of backlinks each is harder to crack than a KD score of 55 where smaller sites with modest link profiles are ranking because no one has written a definitive piece on the topic yet. The SERP tells you the real story. KD gives you a starting shortlist.