@Cascadian You could try it here: https://www.webfx.com/tools/read-able/ There are others out there but that's one of them. Just copy and paste the content of your chapter into the text box and let it calculate.
@Cascadian I'm about the same. The way I see it, if teens that young can read my novel, I think the older crowd will have no complaints...unless the story is really bad.