Flesch Reading Ease is a metric that attempts to measure how easy a text is to understand. It is based on average sentence length and average word length. Longer sentences could imply the use of more complex syntactic structures, which makes reading harder. This metric Equation gives a score between 0 and 100, with lower values indicating a higher level of difficulty. $FRE=206.835-1.015(\frac{number\: of \: words}{number\: of \: sentences})-84.6(\frac{number\: of\: syllables}{number\: of\: words})$.

Flesch-Kincaid Grade Level is a recalculation of FRE, so as to correspond to grade levels in the United States Equation (6). The coefficients were derived from multiple regression procedures in reading tests of 531 Navy personnel. The obtained score should be interpreted in an inverse way as for FRE, so that lower values indicate a lower level of difficulty. $FKGL=0.39(\frac{number\: of\: words}{number\: of\: sentences})+11.8(\frac{number\: of \: syllables}{number\: of\: words})-15.59$.