Flesch-Kinkaid Readability Test

Your website content is one of the most fundamental and important aspects of your website, yet often has the least attention regarding its accessibility.

In order to make your content available to the broadest audience possible, you need to make it as readable as possible. You can test your content with a Flesch-Kinkaid test, which follows this formula to determine how readable it is:

206.835 - 1.015 (\frac{total words}{total sentences}) - 84.6 (\frac{total syllables}{total words})

The higher the score, the more readable your content is, and scores map to a rough "reading-age":

Table mapping reading scores to reading ages
Score	Age	Notes
n ≥ 90	10-11	Very easy to read. Easily understood by an average 11-year-old student.
90 > n ≥ 80	11-12	Easy to read. Conversational English for consumers.
80 > n ≥ 70	12-13	Fairly easy to read.
70 > n ≥ 60	13-15	Plain English. Easily understood by 13 to 15 year-old students.
60 > n ≥ 50	15-18	Fairly difficult to read.
50 > n ≥ 30	18-19	Difficult to read.
n < 30	19+	Very difficult to read. Best understood by university graduates.

To this end, I've made a tool that can calculate the reading level of your own text.

Ages 10-11, very easy to read. Easily understood by an average 11-year-old student.
Ages 11-12, easy to read. Conversational English for consumers.
Ages 12-13, fairly easy to read.
Ages 13-15, plain English. Easily understood by 13- to 15-year-old students.
Ages 15-18, fairly difficult to read.
Ages 18-19, difficult to read.
Ages 19+, very difficult to read. Best understood by university graduates.

This type of test is specifically aimed at English content. Testing readability for other languages is difficult because of the requirement of this formula to count syllables, making it less than suitable for languages such as Arabic, for example.