The Flesch Reading Ease and Flesch-Kincaid Grade Level are two of the oldest and most popular readability tests available. Flesch reading ease measures the textual difficulty of a text in English using a prescribed formula. The formula is a simple approach to assess the grade-level of the reader. Rudolph Flesch, an author, writing consultant, and a supporter of the Plain English Movement, developed this formula in 1948. With a PhD in English from the Columbia University, Flesch advocated a return to phonics and proposed the Flesch Reading Ease Readability Formula. Primarily used to assess the difficulty of a reading passage written in English, it is also one of the few accurate measures around that we can rely upon without too much scrutiny. It is even available as a ‘review’ summary on Microsoft Office’s Word application.
The lower the score, the more difficult the text is. The Flesch readability score uses the sentence length (number of words per sentence) and the number of syllables per word in an equation to calculate the reading ease. Texts with a very high Flesch reading ease score (about 100) are very easy to read. They have short sentences and no words of more than two syllables. Usually, a reading ease of 60-70 is believed to be acceptable/ normal for web copy.
90-100 : Very Easy
80-89 : Easy
70-79 : Fairly Easy
60-69 : Standard
50-59 : Fairly Difficult
30-49 : Difficult
0-29 : Very Confusing
The limitations to its use are the fact that periods, explanation points, colons and semicolons serve as sentence delimiters; each group of continuous non-blank characters with beginning and ending punctuation removed counts as a word; each vowel in a word is considered one syllable subject to: (a) -es, -ed and -e (except -le) endings are ignored;
(b) words of three letters or shorter count as single syllables; and
(c) consecutive vowels count as one syllable.
In editing, I have found that the Flesch reading ease helps me measure the overall beauty of a book’s sentences so I check it before I begin line editing and I check afterwards. It is most useful for academic texts and children’s literature but it is applicable to all essay forms of writing and can help an editor measure the progress of a manuscript.