App Store keyword difficulty, explained
Every ASO tool shows a difficulty score next to a keyword. Almost none of them explain what it's actually built from, or why two tools can disagree on the same word by 20 points.
A difficulty score is an estimate built from the apps currently ranking for a keyword, not a measurement of the keyword itself.
A keyword difficulty score is trying to answer one question: if you started ranking for this keyword from zero today, how hard would it be to break into a competitive position. Every ASO tool estimates it from broadly the same signal set: how many apps are already ranking for the term, how strong those apps are (install volume, rating count, how long they've held their position), and how directly the term matches the top apps' own metadata.
Why two tools disagree on the same keyword
Tools disagree because they weight those signals differently, and because they don't all sample the same slice of the search results. A tool that leans harder on install-volume estimates will score a keyword dominated by one huge app as harder than a tool that leans on metadata match will. Neither is wrong; they're measuring slightly different things and calling the result the same name.
What the score is useful for, and what it isn't
Difficulty is genuinely useful for triage: sorting a list of 50 keyword candidates down to the 10 worth spending your 100-character keywords field on. It's much less useful as a precise forecast; treating a difficulty score of 62 as meaningfully different from 58 is over-reading a number that's an estimate to begin with. Use it to separate clearly-easy from clearly-hard, and rely on your own rank tracking afterward to see what actually happened.
A rule of thumb for a small app
If your app has under a few hundred ratings, keywords where the current top 5 results are all large, established apps are usually not worth prioritizing, regardless of what the difficulty number says exactly. Keywords where the top results are a mix of smaller or less-optimized apps are where a metadata change is most likely to actually move your rank.
Popularity and difficulty are not the same axis
A high-popularity, low-difficulty keyword is the best case: lots of search volume, and a realistic path to ranking. A high-popularity, high-difficulty keyword usually isn't worth the character budget for a small app; a low-popularity, low-difficulty keyword can still be worth including if it's cheap in field space to add and converts well. Treat the two scores as a 2x2, not a single ranking.
Difficulty scoring is one of the criteria we compare across all 9 tools in our ASO tool ranking.
Frequently asked questions
What does an App Store keyword difficulty score actually measure?+
An estimate of how hard it would be to rank competitively for that keyword today, built from signals like how many apps already rank for it, how strong those apps are, and how closely they match the term in their own metadata.
Why do different ASO tools show different difficulty scores for the same keyword?+
Each tool weights the underlying signals differently and samples the search results slightly differently, so their scores are estimates of related but not identical things, even when both call the result 'difficulty.'
Should I trust the exact difficulty number, or just the rough range?+
The rough range. Use it to sort a long list of keyword candidates into clearly-easy versus clearly-hard; treating small differences (58 vs 62) as meaningful over-reads an inherently estimated number.
Is a low-difficulty keyword always worth targeting?+
Only if it also has enough search popularity to matter. Pair difficulty with popularity before deciding; a low-difficulty, low-popularity keyword may not be worth the character-field space it costs.