The Raygor Estimate Graph is a readability measurement for English-language text, developed by Alton L. Raygor (1977).

You calculate the U.S. grade level by counting the average number of sentences and letters per 100 words. You plot these averages onto a specific graph. The intersection of the average number of sentences and the average number of letters/words determines the reading level of the text. If you've used the Fry Readability Formula, you will notice that the graph is very similar to the Fry graph.


You can use the Raygor Estimate Graph in secondary education to help classify teaching materials and books into their appropriate reading groups and age ranges.


( Raygor Estimate Graph - Large Image )

Here is how you calculate and plot the Raygor Estimate Graph:

1) Extract a 100-word passage from the selection. If the material is long, take a subsample from the beginning, middle, and end. Don’t count any numerals unless they are written out as numbers.

2) Count the number of sentences in each passage. Count a half sentence as .5.

3) Count or underline the number of words in each passage containing six or more letters.

4) To plot the results on the Raygor graph, find the total number of sentences in your passage on the vertical axis of the Raygor scale and place a dot on the margin closest to your number. Next find the number of words with six or more letters on the horizontal axis; and again place a dot closest to that number. Now find the place where the dots intersect on the graph. The grade level is where your dot intersect. The grade level is valid within the "parallel" lines. If your plot is in the top left area of the grid or the bottom right (outside the parallel lines) your total is invalid.

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