Lexical Diversity Calculator

Work out lexical diversity instantly with clear inputs, formula shown and shareable results.

About Lexical Diversity Calculator

Type-token ratio is unique words over total words: 310 types in 1000 tokens gives 0.31. Its weakness is length dependence - longer texts inevitably repeat words, so TTR falls even when vocabulary is rich. Root TTR and log TTR correct for that, which is why they are preferred when comparing texts of different lengths.

Formulas

Type-token ratio

TTR = unique types / total tokens

Length-corrected forms

root TTR = types / sqrt(tokens); log TTR = log(types) / log(tokens)

Worked example

With the default values below, Lexical Diversity Calculator returns Type-Token Ratio of 0.3100. Change any input above and every figure here is recalculated in your browser.

Inputs used

Unique word typesminimum 1: 310
Total word tokensminimum 1: 1,000

Results

Type-Token Ratio: 0.3100
Root Type-Token Ratio: 9.803
Logarithmic Type-Token Ratio: 0.8305
Interpretation: Typical for extended prose

Step by step

1Values used
2Type-token ratio
3Length-corrected forms
4Type-Token Ratio= 0.3100
5Root Type-Token Ratio= 9.803
6Logarithmic Type-Token Ratio= 0.8305
7Interpretation= Typical for extended prose

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why does TTR fall with text length?

Because function words repeat constantly. Once the common vocabulary is used, each additional token is more likely to be a repeat.

Which measure should I use?

For comparing different lengths, use a corrected measure such as MTLD or root TTR. Plain TTR is only valid at a fixed sample size.