Comparison
decide whether to audit content for keyword balance or for how easy it is to read.
Both tools help you sharpen a piece of writing before publishing, but they measure different qualities. Keyword Density checks the ratio of your target term to the total word count — a signal to search engines about topic focus. Readability scores how easy the copy is for a human to read (Flesch, grade level).
High keyword density with poor readability reads spammy. Low density with high readability reads pleasant but doesn't rank. Great pages score well on both.
| Feature | Keyword Density Checker | Readability Checker |
|---|---|---|
| Measures | Term frequency vs. total words | Sentence length, syllables per word, Flesch score |
| Audience | Search engines | Human readers |
| Ideal target | 0.5%–2.5% for primary keyword | Grade level 6–9 for general audiences |
Run Readability Checker first — if the copy doesn't read well, keyword density won't save it. Then use Keyword Density Checker to confirm your target term shows up enough times without stuffing.
Roughly 0.5%–2.5% for the primary term. Above 3% risks over-optimisation flags; below 0.5% and the topic focus is thin.