We all know that Microsoft Word can check spelling and grammar. LifeHack.org points us to a little-known (well, to me, anyway) feature of Word that tests writing against the Flesch-Kincaid readability test. I recall using FK tests years ago, as a technical writer; I never thought to look for them in Word.
The next time you write a document, click Tools, Options, and go to the Grammar and Spelling tab. Check the box marked “Show Readability Statistics”. Word will present these statistics the next time you do a grammar check.
Note that smaller, easily-recognizable words are generally more understandable than longer words, and that this is (in effect) a mathmetical computation of readability, and therefore, imperfect. It may not recognize technical terms, colloquialisms and the like.
LifeHack: “How easy is your writing to understand?”.