What a Mathematical Formula Can Teach You About Good Writing

For MSPC senior content director Molly Bennett, a complex readability test is a reminder of the simple lessons we all learn about communicating effectively.

If you’re not familiar with Flesch-Kincaid readability tests, pull up a chair.

(Wait, don’t go! I promise it will get better.)

Way back in the 1970s, a Mr. Flesch and a Mr. Kincaid developed these tests for the U.S. Navy. The aim was to overhaul the Navy’s technical manuals to ensure that everyone—even those at a sixth-grade reading level—could understand them. A worthy cause indeed, I hope you’ll agree.

In the ensuing decades, the tests made their way into corporate style guides across the English-speaking world. Today, if you so desire, you can find a “readability statistics” function within Microsoft Word’s spelling and grammar checker.

The Flesch-Kincaid tests are based on a formula looks like this:

(Listen. Can you hear that? That’s the sound of Emily Dickinson spinning in her grave.)

SEO Versus Flesch-Kincaid

Under this model, the higher an article scores, the easier it is to read. The formula penalizes long words. It rewards short sentences. And taken to its extreme, a high Flesch-Kincaid score results in staccato, “See Spot run” writing that is simultaneously boring, artless and patronizing to anyone above the age of 2.

Many corporate style guides suggest an ideal range of 60 to 70. But heaven help you if you’re trying to optimize your copy for search, and said copy is for a client in a highly technical industry. You can have a high F-K score, or you can have your “privileged access management” keyword, but you sure can’t have both.

But when one client adopted this measure of readability, we duly embarked on a meet-and-greet with Flesch-Kincaid. And after much experimentation, we cracked the code. Are you five points under your target? Just add periods to the end of every bullet point! Hey, did you know the formula actually favors passive construction? (My computer was nearly thrown out the window.)

Soon enough, I found myself Googling “Flesch-Kincaid is the worst” in a fit of writerly pique. My search unearthed an example of 95-point text that felt as though the author was throwing small pebbles at my head repeatedly. To my mind, it was the antithesis of an easy read. Where was the rhythm? Where was the flow? Did we really need to sacrifice art in favor of science?

But what a corporate style guide decrees, we fulfill. We found workarounds that allowed us to achieve a reasonably high score without sacrificing too much of the art. And hopefully, the finished articles sound less like excerpts from a Step into Reading book than well-written pieces of content for grownups.

Getting to the Heart of Flesch-Kincaid

When it comes down to it, Flesch-Kincaid just puts a hard number on what good communicators already know. Be clear. Be concise. Don’t use a long word when a short one will do. If in doubt, cut it out.

Today, despite my best efforts, Flesch-Kincaid has wormed its way into my brain. I can now spot a 30-word sentence at 100 paces. I can’t stand semicolons. Just break it into two sentences, for crying out loud! Don’t you know what it’s doing to your F-K score?

Because in this line of work, we’re not creating content for our own amusement. We’re writing for people. And if experimenting with Flesch-Kincaid helps us see the (literal) value of writing that speaks to more people, rather than fewer, then that’s OK in my book.

P.S. If you’re curious, this article scored 69, or a grade level of 6.8. And I’m not going to lie: It feels good.

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