Vocabulary Diversity Calculator (Type-Token Ratio)
Type-token ratio and unique word count for a text, with the repeated words that drive the result.
What is Vocabulary Diversity?
Vocabulary diversity, or type-token ratio, is the number of distinct words divided by the total words: 0.5 means half the words in the text are used only once. It is the standard measure of how varied the vocabulary is, and it has a property that makes it easy to misuse — TTR falls as a text gets longer, because the words already used keep reappearing while the supply of new ones runs out. Comparing a 200-word paragraph with a 2,000-word essay on this number compares lengths, not vocabularies.
How it works
Words are tokenised and lower-cased, and the distinct count is divided by the total to give the ratio, reported as a percentage. Because of the length dependence, the tool also reports the counts the ratio is made of — how many distinct words were used once and how many were repeated — and charts the most frequent words, which is where the number becomes actionable: a low ratio is usually a handful of words carrying the whole text. For comparing two texts of different lengths, the per-100-words distinct count is reported alongside the ratio, which is a length-normalised reading of the same data.
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Examples
Realistic sample
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Common mistakes
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