WDF

WDF stands for Within Document Frequency and is a logarithmic metric that measures how often a term appears in relation to all other terms in a document. Combined with IDF, the Inverse Document Frequency, it forms the WDF*IDF formula used in content SEO. It helps you compare the thematic depth of a text against competitors.

How the calculation works

WDF dampens very frequent terms through a logarithm so a single, repeatedly mentioned term does not distort the value. IDF in turn weights how rarely a term appears in a reference corpus, for example in the top ten search results for a keyword. The product of both values shows which terms in your own text are underrepresented and offer room for improvement.

Practice in search engine optimisation

SEO tools such as Seobility, Searchmetrics, or Termlabs deliver finished WDFIDF analyses and recommendations on which terms or phrases to add. Pitfall: WDFIDF does not replace editorial quality, it complements it. Writing texts solely from a term list produces soulless keyword stuffing that readers and modern ranking models both recognise.

Context in content marketing

In the content workflow WDFIDF is a tool for optimising existing pages, for instance when an article ranks just outside the top ten. You identify missing terms, revise the text, and publish the new version. Modern search engines increasingly work semantically, which keeps WDFIDF a useful orientation but not a sole success factor.