A keyword difficulty check usually means looking at a number a tool produced. That number is a model of how strong the currently ranking sites are, and it is a reasonable way to sort a long list quickly. It is a poor way to decide, because it knows nothing about your site, nothing about how well those pages actually answer the query, and nothing about whether the intent is one you can serve better than a big site can.
What the score is actually modelling
Almost every difficulty score is built from the strength of the domains ranking for the query. That captures something real, because standing matters, and it misses the two things that decide most outcomes for a small site: whether the ranking pages are genuinely about this query, and whether you have something to say that they do not. A score cannot see either, and both are visible in ten minutes of looking.
The check that beats the score
Open the results and read the top five. Are they pages about exactly this question, or pages about something adjacent that mention it? Are they specific, or general? Written by somebody who has done the thing, or assembled? A query where every result is a precise, first-hand answer is hard whatever the score says. A query held by broad pages that miss the point is open, whatever the score says.
Recognising a genuinely competitive query
Highly competitive queries tend to be short, broad, commercially obvious, and held by sites whose whole business is that subject. They also tend to have result pages crowded with features that take the clicks before any ordinary result appears. If a query has all of those, a small site should leave it and take the specific questions underneath it instead, which is not a consolation prize: it is where the buyers with a decision to make actually are.
Difficulty is relative to you
The same query is easy for a site with years of standing in the subject and impossible for a new one. Any single difficulty number pretending to apply to everyone is hiding that. Judge against your own site: what are you already credited for, and is this query next to that or far from it?
Questions people ask about keyword difficulty check
How accurate are keyword difficulty scores?
They are models of the ranking sites' strength, useful for sorting a long list and unreliable as a threshold. Different tools produce different numbers for the same query.
How do I check difficulty without a tool?
Read the top results. Judge whether the pages actually answer the query and whether you could answer it better or more specifically.
What makes a keyword highly competitive?
Short, broad, commercially valuable, held by specialists, and with a result page crowded by features. Any two of those should give you pause.
Should I ever go after a hard keyword?
Sometimes, deliberately, knowing it is a long play. What you should not do is spend a year of pages on hard queries by accident because a list was sorted by volume.