Ever wondered how the reading level of a book is determined or wanted to figure it out yourself? There are a number of methods available for determining just that for any written passage. We’ll look at several methods: the Gunning Fog Index, the Flesch Formula and the Powers Sumner Kearl Formula. In each method you analyze a passage of text for word and sentence patterns calculating a score and then comparing it to an index. Each index should be seen as a rule of thumb, not an absolute. Highly jargon filled technical writing may have a lower score but still be difficult to read for those not already conversant with the terms used. The indexes also are keyed to grade levels, which may not hold true with the constant shifting in what is expected from children at a particular grade level. One school’s third grader is another school’s fifth grader, with homeschoolers pretty much throwing the whole notion of grade levels out the window. Different indexes or formulas will generate different results for the same text. For example this article was given a grade level of 7.0 using the Gunning Fox Index and a Flesch Reading Ease level of 49 equivalent to college level. Still the indexes can give you some useful information in comparing one book with another.

Gunning Fog Index

The Fog Index measures readability for upper elementary and secondary ages. Select several samples of 100 words and apply the following steps:

1. Count the number of words in the sample.
2. Count the number of sentences
3. Count the number of big words (3 or more syllables)
4. Calculate the average sentence length. Divide the number of sentences into the number of words.
5. Calculate the percentage of big words. Divide the number of words into the number of big words
6. Add the average sentence length to the percentage of big words
7. Multiply the result by .4. The resulting number is the readability grade level.

The Flesch Formula: Reading Ease & Grade Level

The Flesch Formulas work well with upper elementary and secondary texts. Select several samples of 100 words and apply the following steps:

1. Count the number of words in the sample.
2. Count the number of sentences.
3. Divide the number of words by the total number of sentences. Multiply that result by 1.015.
   (Number of words ÷ number of sentences)* 1.015 = A
4. Count the total number of syllables. Divide by the total number of words and multiply by 84.6. (Number of syllables ÷ number of words) * 84.6 = B
5. Add the results from steps 3 and 4. And subtract from 206.835. 206.835 - (A + B)
6. The results of step 5 are the Reading Ease score.

Reading Ease Score Difficulty Flesch Grade Level

Powers Sumner Kearl Formula

The Powers Sumner Kearl Formula measures the readability of primary age books for readers ages 7 - 10. Select samples of 100 words.

1. Count the number of words in the sample.
2. Count the number of sentences.
3. Calculate the average sentence length (L). L = number of words ÷ number of sentences
4. Count the number of syllables (N).
5. Calculate grade level (L × 0.0778) + (N × 0.0455) - 2.2029
6. Calculate reading age (L × 0.0778) + (N × 0.0455) + 2.7971 years

Counting words and syllables can be time consuming. Fortunately those who have access to Microsoft Word or Corel WordPerfect have there own readability calculator. Word generates readability statistics using several different methods including Flesch Reading Ease and Flesch-Kincaid Grade Level. To determine readability of any document, first, use the grammar tool to check grammar. After the grammar check is completed the document’s readability statistics will be displayed. In Word Perfect select Grammatik from the Tools menu. Select the Options button and then analysis and readability. Word Perfect generates statistics on the Flesch-Kincaid grade level, passive voice, sentence complexity and vocabulary complexity. It also compares the scores of the document you are analyzing with another document. Already available are a Hemingway short story, the Gettysburg Address, and the 1040EZ Tax Instructions. You can use it to check your own or your children’s writing or type a passage from any book to determine its readability.

When analyzing text you will get better results by analyzing longer passages or taking three 100-word passages from different sections of a book. You can also create your own benchmark standards by analyzing books that you know are easy or more difficult for your child to read. Compare new books to your benchmarks to determine whether your child will find a book below, at or above his reading level.