Gunning-Fog Readability Formula

Use this to analyze your book for reading difficulty level:

  1. Open the book to a random page with at least two paragraphs.
  2. Count out a section of 100 words.
  3. How many sentences are in the sample? Divide 100 by the number of sentences to get the average number of words per sentence.
  4. Look over the sample again and count the number of words that have three or more syllables, but don't count words that make three syllables because of an additional "ing" of "ed". These are your "difficult" words.
  5. Add the average number of words per sentence to the number of multisyllabic words.
  6. Multiply this by .4.
  7. The number you have left is a rough "grade level" of this section of text.

1-6 elementary level
7-9 junior high
10-12 senior high
13-16 college
>17 graduate level


a. Count a 100 word sample. Write the number of sentences: _______
b. Divide 100 by the number of sentences: (100/"a") _______
c. Count the number of words with three or more syllables: _______
d. Add "b" + "c": _______
e. Multiply this by .4 = grade level: _______

Repeat this with two more samples from the book. If you get a wide variation between samples, do it again in another section, and again if needed until you start to see a trend.


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Which book did you analyze and what was the average reading level of the text?

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