Readability tests are tests conducted on passage samples designed to measure how difficult a reading passage is. There are several readability tests, all of which are related to the average number of words per sentence. They are generally used by people who want their writing to be reached by a broad audience.

The two major readability tests are:

• The Fog Index
• The Flesch-Kincaid Readability Test (including the "Flesch-Kincaid Reading Ease" and the "Flesch-Kincaid Grade Level Formula")

While the readability tests are not perfect, they can still give a general idea of how difficult a passage is to comprehend.

External links

http://developer.gnome.org/documents/usability/usability-readability.html