What is Keyword difficulty?
Keyword difficulty is an estimated score, usually 0–100, of how hard it would be to rank on the first page for a search phrase, based mainly on the authority and backlink profiles of the pages already ranking there.
Also called: KD, keyword competition, ranking difficulty.
It is an estimate produced by a tool, not a fact about the internet, and different tools disagree wildly on the same phrase. Treat it as a rough sort order for your options rather than a verdict.
What it usefully captures is that a new site cannot fight established authority head-on. If the first page for a phrase is three national brands and two comparison sites, your difficulty is effectively 100 regardless of the number displayed. If it is two thin directory listings and a competitor's neglected page, a good page can win in weeks.
The better habit is to look at the actual results page before believing any score. Who ranks, how good is their page, and could yours honestly be more useful to the person searching? That question answers difficulty more reliably than the number.
What to actually do about it
- Sort candidate keywords by difficulty, then judge the results page yourself.
- Start with phrases where the current top results are weak or off-topic.
- Treat local phrases as easier — proximity and reviews outweigh authority.
- Ignore volume-with-high-difficulty phrases for at least your first year.
- Re-check difficulty annually as your own authority grows.
Koo scores every keyword it finds against your site's current authority, so the suggestions you see are ones you could plausibly win now rather than a wish list.
Related terms
Long-tail keyword
A long-tail keyword is a longer, more specific search phrase with lower search volume but clearer intent and far less competition — for example "repair a leaking radiator valve in Leeds" rather than "plumber".
Topic cluster
A topic cluster is a group of related pages built around one broad "pillar" page, all interlinked, which signals to search engines that a site covers a subject in depth rather than mentioning it once.
Backlink
A backlink is a link from another website to yours. Search engines treat it as a vote of confidence, so links from relevant, trusted sites remain one of the strongest ranking signals.