Lexile AnalyzerThe Lexile® measure of text is determined using the Lexile Analyzer®, a software program that evaluates the reading demand—or readability—of books, articles and other materials. The Lexile Analyzer measures the complexity of the text by breaking down the entire piece and studying its characteristics, such as sentence length and word frequency, which represent the syntactic and semantic challenges that the text presents to a reader. The outcome is the text complexity, expressed as a Lexile measure, along with information on the word count, mean sentence length and mean log frequency.