How To Be A Better Writer: Your Flesch-Kincaid Score

How To Be A Better Writer by Charles Sledge

One of the most important parts of being a good writer is making sure that your readers understand what you are saying. Despite what most think overwrought prose is not the mark of an intelligent mind but rather the mark of someone who has no idea how to write. One of the most important facets of being a good writer is being able to communicate through your writing clearly and succinctly. Large words and long pages are not the mark of a good writer, but rather the mark of an amateur. Those most “writers” would be loathe to admit it but writing good prose has a lot in common with writing a good advertisement.

In a good advertisement not a single word is wasted, only words that the readers understand are used, there is plenty of repetition, and the point isn’t hidden but rather attention is drawn to it. The average novelist or non-fiction writer has a lot to learn from the good copywriters. One test that copywriters use to make sure the copy they are writing in their advertisements are working is put it through the Flesch-Kincaid readability test which shows you at what grade level you are writing at. For the average audience anything above a 6 and you’ll be losing them.

The Importance Of Flesch-Kincaid

The test for first devised for the U.S. Navy back in the 70’s and had something to do with computers. Honestly that’s not what’s important. What’s important is how you can use it to make sure that your readers are understanding what you are writing. Because after all it doesn’t matter how amazing your point is, it could be exactly what the reader is looking for, the answer to all of their problems. But if they don’t understand what it is that you’re saying then it’s not going to matter how profound your points are.

Simple, clear prose is the mark of a good writer. When in doubt always go lower on the Flesch-Kincaid readability index. There is no risk in going lower (to an extent perhaps if the most complex sentence in your copy is “Bob happy” then you can move it up) but there is a risk in going higher. Every level you ascend up another portion of the population drops out that can’t understand your work. This is bad regardless if you’re a novelist or an ad man. Lack of understanding leads to lack of buying and lack of supporting.

How The Flesch-Kincaid Readability Index Works

Alright so now you want to test it out. Follow the steps below and you’ll end up with your Flesch-Kincaid readability index

Step #1 – Choose Your Sample

Alright so the first thing you want to do is choose a sample that is going to be representative of the work as a whole. So for example you could choose a random page out of a book (that isn’t a chapter ending or beginning). You could do a numerical number where you pick every third sentence of every third page for x amount of pages. Or you can use another option. You want to make sure that the sample you pick is going to be somewhat of an average of the entire work.

Step #2 – Count The Words

This is pretty self-explanatory. The next thing that you are going to do is count the number of words in the sample. Numbers, hyphenated words, and contractions all count as one word. So all of the following would count as one word self-esteem, 1993, and P.O.S. for example. This can be very simple if you sample has exactly 100 words by the way.

Step #3 – Figure The Average Sentence Length

The next thing you are going to do is calculate what the average sentence length is. So take all of the words total and then divide them by the number of sentences. Again pretty self-explanatory.

Step #4 – Calculate The Average Number Of Syllables Per Word

Again pretty self-explanatory. Take the total amount of syllables and divide them by the total number of words. And you’ll end up with the average number of syllables per word.

Step #5 – Do The Multiplication (And Addition)

Alright here is where it gets a little interesting. You are going to take the average number of words and multiply that amount by 0.39 and then you are going to multiply the average number of syllables per word by 11.8. Then you are going to add those two numbers together.

Step #6 – Subtract

Then you are going to subtract 15.59 from the total and you’ll end up with your Flesch-Kindcaid readability index score. So for example if you ended up with a score of 9.5 you be writing at a level that a ninth grader could read halfway through his ninth grade year (and remember this was 1970 9th grade not modern).

Here is what the formula looks like expressed mathematically: FKRI = (0.39 x ASL) + (11.8 x ASW) – 15.59. With ASL standing for average sentence length and ASW standing for average syllable per word.


While that no doubt seems pretty complicated one you’ve used it a couple of times it gets easier and easier. Measuring your Flesch-Kincaid readability index score is very important to make sure that your words are getting across to you reader and carrying the punch that they need. Remember you want to make sure that you are ranking under a 6.0. If you’re scoring higher than that then you’ll want to rework some things until you have a better score. Now you have a scientifically and mathematically proven way to make sure that your writing is good and readable.

If you have any questions you would like to see answered in a future post send them to me at charlessledge001 (at) gmail (dot) com. If you found value in this post then I would encourage you to share this site with someone who may need it as well as check out my books here. I appreciate it. You can follow me on Twitter here.

-Charles Sledge

Charles Sledge