What makes a text readable?

The most readable text is one that you know all the vocabulary, and the sentences are not too long for your level of comprehension.

It's important to note that your reading comprehension skill can vary widely throughout the day. Early in the morning, when your mind is bright and fresh, you comprehension is at the highest. Late at night, when tired, your comprehension dips to a low point. Many students of foreign languages notice that trying to understand a foreign language when tired is exceptionally difficult.

The Readability grade level scores given for each section of text on this website are calculated using the RIX formula. The RIX formula can be used on documents of most Western European Languages:

Total number of long words (6 or more letters) Total number of sentences = RIX \frac{Total number of long words (6 or more letters) }{Total number of sentences} = RIX {Total number of long words (6 or more letters)} over {Total number of sentences} equals RIX

The ratio of these two values provides the ranking. The table below provides a breakdown of how the ratio maps to a grade level comprehension.

RatioGrade Level
7.2+College
6.2+12
5.3+11
4.5+10
3.7+9
3.0+8
2.4+7
1.8+6
1.3+5
0.8+4
0.5+3
0.2+2
0 to 0.21

For additional information on the RIX formula, see Thomas Jakobsen and Thomas Skardal's published paper: Readability index Also of note is Eleni Miltsakaki and Audrey Troutt's paper: Read-X: Automatic Evaluation of Reading Difficulty of Web Text.

Written by Todd Cook. Language enthusiast, modern outdoorsman, software craftsman. Find him on or

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