Yes, this is a tool that evaluates the "readability" of an article based on three metrics: the Flesch Reading Ease (Flesch), Flesch-Kincaid Grade Level (Kincaid), and Gunning fog (Fog) scores. The scores are determined by a mathematical formula involving word count, syllables, and number of sentences.
Give it a whirl! How "readable" is your content?
These metrics are simply an indicator as to whether a body of text is easy to comprehend. By understanding your target audience, you can write content that is appropriate to their reading abilities.
For reference, a Flesch Reading Ease score between 60 and 70 would be appropriate for most 13- to 15-year olds. When this metrics decreases, the content is seen as more difficult to read.