Keyword Density

Keyword density is the percentage of times a keyword or phrase appears in a piece of content relative to the total word count. The formula is straightforward: divide the number of times your target keyword appears by the total number of words, then multiply by 100. A 1,000-word article that mentions "content marketing" 15 times has a keyword density of 1.5% for that phrase.

Keyword density was once treated as a major ranking factor. In the early days of SEO, marketers obsessively tuned density to 2-3% believing it would help pages rank. Modern search engines have moved well past that simplification. According to Semrush's keyword-density guide, density is now considered an "on-page relevance signal" — useful for sanity-checking that your content is genuinely on-topic, not for ranking manipulation.

The widely cited "healthy" zone, per Yoast's official keyphrase density check, is between 0.5% and 3%. Below 0.5% is too sparse for search engines to clearly recognize your topic. Above 3% starts to feel like forced repetition that hurts readability. Above 4% is the stuffing zone that Google's spam policies explicitly call out as a violation. There is no "perfect" number — write for humans first, then sanity-check with a tool.

Modern SEO best practice is to focus on semantic relevance and natural language rather than a single keyword repeated a target number of times. Use related terms, synonyms, and variations naturally throughout the content. A keyword density checker can help you spot over-optimization, but the goal is content that reads well to a human, not content that hits a magic number.