Appendix D READING EASE SCORE
Many indices of reading ease have been derived. One such is Flesch's fog index and reading age. (Fog meaning 'frequency of gobbledygook'!) A slightly simplified version is below.
The grammar checker in Word can calculate a fog index for you. However it seems to use a different method of calculation from that presented here.
Notice that this gives the Reading Age. A person's reading age may be very different from their calendar age; it is the complexity of reading material they an cope with.
Fog index = 206.8 - (s + 0.85 w )
where
s = average number of words per sentence
w = number of syllables per 100 words (based on a sample of typical text).
|
Fog Index |
Reading Age |
|
|
90 - 100 |
Very Easy |
10 Years |
|
80 - 90 |
Easy |
11 Years |
|
70 - 80 |
Fairly Easy |
12 Years |
|
60 - 70 |
Standard |
13-14 Years |
|
50 - 60 |
Fairly Difficult |
15-16 Years |
|
30 - 50 |
Difficult |
16-18 Years |
|
Under 30 |
Very Difficult |
Over 18 Years |