The Flesch Reading Ease measures textual difficulty, which indicates how easy a text is to read.
How it works
The Flesch Reading Ease Scale measures readability as follows:
100: Very easy to read. Average sentence length is 12 words or fewer. No words of more than two syllables.
65: Plain English. Average sentence is 15 to 20 words long. Average word has two syllables.
30: A little hard to read. Sentences will have mostly 25 words. Two syllables usually.
0: Very hard to read. Average sentence is 37 words long. Average word has more than two syllables.
The higher the rating, the easier the text is to understand. By the very nature of technical subject matter, the Flesch score is usually relatively low for technical documentation. If the Flesch test is used regularly, one may develop a sense of what a reasonable score is for the type of documentation one is working on and aim to align with this score. The approach to calculating the Flesch score is as follows:
1. Calculate the average sentence length, L.
2. Calculate the average number of syllables per word, N.
3. Calculate score (between 0-100%).