Keyword Density Checker

Keyword density is the ratio of a single term's occurrences to the total word count, usually expressed as a percentage. It was a primary on-page signal in the early 2000s, when matching algorithms were largely lexical and a higher count of a phrase could meaningfully shift a ranking. That world is gone — Google's BERT, MUM, and the broader Helpful Content System now score topical coverage and entity relationships, not raw frequency.

The analysis here runs entirely in client-side JavaScript. Your text is split on whitespace and Unicode word boundaries, lowercased, and counted with a Map keyed by token. Single-word frequencies, bigrams (two-word phrases), and trigrams are all derived from the same pass, so even very long articles update in a few milliseconds without leaving the tab.

A built-in stop word list filters function words like the, and, is, of, a, to, in before reporting frequencies. Without that filter, articles and prepositions dominate the top of any English text and obscure the topical terms you actually care about. You can disable the filter if you want a raw distribution for stylometric or readability work.

The classic stuffing threshold is roughly 3-4% for a single term in an English document of meaningful length. Above that, prose tends to read awkwardly to humans, and Google's spam systems may flag the page. Below 0.5% on a long article often indicates the topic is not discussed enough for the target keyword to be the page's clear subject.

Bigram and trigram views surface multi-word patterns that the unigram view hides — phrases like content marketing strategy or local business schema are usually what searchers actually type. These are also the phrases LLM-driven retrieval systems weight heavily when extracting passages for AI overviews.

Keep in mind the tool measures one document at a time and has no awareness of synonyms, stems, or related entities. A page that says automobile twelve times and car never will look balanced to a human reader but score zero for the keyword car. Treat density as a sanity check on the writing, not as a target to optimize toward.

Use the output to tune wording: trim runaway repetitions, vary phrasing, and confirm your primary keyword appears enough times to make the page's subject obvious without crossing into mechanical repetition. That is the only role density still plays in 2026 SEO.