Flesch reading Ease

The output of the Flesch Reading Ease formula is a number from 0 to 100, with a higher score indicating easier reading. The average document has a Flesch Reading Ease score between 6-70. The formula reads as follows:

Flesch-Kincaid Grade Level

The more common Flesch-Kincaid Grade Level formula converts the Reading Ease Score to a U.S. grade-school level.

In addition, more than 40 readability formulas have been developed over the years (Klare, 1974-1975). Readability measures guide the construction of textbooks such that the readability conforms to the intended grade level. However, there are at least three major problems with readability formulas that prevent valid predictions of text comprehension.

1. Surface characteristics. Readability scores are based on the surface characteristics of the text. Comprehension and learning, however, depend to a greater extent on processing at the textbase and situation levels (Kintsch, Welsch, Schmalhofer & Zimny, 1990; McNamara et al., 1996). Measuring text elements that are primarily needed for surface processing does not adequately capture comprehension and learning, which is the concern of educators. Recent advances in discourse processing and computational linguistics afford more advanced measures of readability due to more precise predictions of which text characteristics improve comprehension and learning.

2. Reader's cognitive aptitudes. Predicting reading, understanding, and learning requires consideration of the reader’s knowledge, language skills, and other cognitive aptitudes. Although text characteristics can certainly predict aspects of readability, readability should be viewed as an interaction between a text and a reader’s cognitive aptitudes (Kintsch, 1994; Miller & Kintsch, 1980; McNamara et al. 1996).

3. Cohesion and coherence. Readability formulas cannot capture the cohesion or coherence of a text. Research has clearly shown that readers have less difficulty reading cohesive texts (Beck, McKeown, Sinatra, & Loxterman, 1991; Britton & Gulgoz, 1991; Gernsbacher, 1997; Graesser, Gernsbacher & Goldman, 2002; McNamara, 2001; McNamara & Kintsch, 1996; McNamara et al., 1996). We would therefore expect greater readability scores for high-cohesion texts than low-cohesion texts; however, this is not generally the case. In the following examples the low cohesion sentences have lower or equal Flesch-Kincaid grades, but are intuitively more difficult to read than the high cohesion texts. Similarly, the Flesch Reading Ease scores do not necessarily differentiate between low and high coherence sentences. Hence, traditional readability measure can run orthogonal to cohesion measures. Average sentence length and average number of syllables per word alone cannot sufficiently predict coherence and therefore understanding of a text.