The readability level is calculated based on the Dale-Chall readability formula. The Dale-Chall readability score is given below:
The words that are regarded as difficult words in the formula are those that do not belong to the list of 3,000 familiar words. If the percentage of difficult words is above 5%, then add 3.6365 to the raw score to get the adjusted score, otherwise the adjusted score is equal to the raw score.
Mapping Dale-Chall Readability Score to Readability level:
|4.9 or lower||easily understood by an average 4th-grade student or lower|
|5.0–5.9||easily understood by an average 5th or 6th-grade student|
|6.0–6.9||easily understood by an average 7th or 8th-grade student|
|7.0–7.9||easily understood by an average 9th or 10th-grade student|
|8.0–8.9||easily understood by an average 11th or 12th-grade student|
|9.0–9.9||easily understood by an average 13th to 15th-grade (college) student|
|10.0 or higher||easily understood by an average college graduate|
What is counted as a word?
A consecutive sequence of printable alphabet letters, numeric letters, hyphens, and markers.
What is counted as a difficult word?
A word that falls outside the list of 3,000 familiar words
What is counted as a character?
Any printable and non-printable characters. Non-printable are trimmed if they are at the beginning or at the end of the text.
What is counted as a sentence?
A set of words that ends by a marker, such as full stop, question mark, exclamation mark...
What is counted as a paragraph?
A set of sentences that ends by a new-line character...
What is counted as Average Word Length?
The quotient of the number of non-space characters over the number of words.
What is counted as Average Sentence Length?
The quotient of the number of words over the number of sentences.