Formula to detect the grade level of text according to the Flesch Reading Ease.

See syllable for detecting syllables.

npm:

npm install flesch

var flesch = require('flesch');

/* For “The cat sat on the mat” (1 sentence, 6 words,
 * 6 syllables). */
flesch({
  sentence: 1,
  word: 6,
  syllable: 6
});
// 116.14500000000001

/* For “The Australian platypus is seemingly a hybrid of
 * mammal and reptilian creature.” (1 sentence, 13 words,
 * 26 syllables). */
flesch({
  sentence: 1,
  word: 13,
  syllable: 26
});
// 24.440000000000026

Given an object containing the number of words (word), the number of sentences (sentence), and the number of syllables (syllable) in a document, returns the reading ease associated with the document.

Returned values are 120 (every sentence consisting of only two one-syllable words), or lower (including negative values).

The values have the following semantics:

• automated-readability — Uses character count instead of error-prone syllable parser;
• coleman-liau — Uses letter count instead of an error-prone syllable parser;
• dale-chall-formula — Uses a dictionary; suited for higher reading levels;
• flesch-kincaid — Like flesch; returns U.S. grade levels;
• gunning-fog — Uses syllable count; needs POS-tagging and NER;
• smog-formula — Like gunning-fog-index; without needing advanced NLP;
• spache-formula — Uses a dictionary; suited for lower reading levels.

MIT © Titus Wormer