The secret SEO formula? Write to Flesch–Kincaid Readability Tests

Posted by Julia McCoy on 11 Jan, 2016
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Have you heard of the Flesch-Kincaid readability tests? If you answered “no”, hold onto your chair because we’re about to tell you something that will change the way you write web content forever.

We all know that writing great copy means writing simple copy – copy that delivers the point without delving into complicated language or convoluted sentences. For some people, though, this is a tall order.

Fortunately, the Flesch-Kincaid readability tests are here to help you determine how readable your content truly is and what you can do to improve it.

Read on to learn more about these nifty tests and how they can revolutionize your content writing experience forever.

What are the Flesch Kincaid Readability Tests?

The Flesch-Kincaid readability tests got their name from J. Peter Kincaid and his team of developers. The tests were originally developed under contract with the US Navy and were designed to assess the difficulty of understanding in technical manuals, around the year 1978. Within a few years, the tests became the standard within the Department of Defense and quickly spread throughout government.

What do the tests test for though? Essentially, the tests break text down into two parts (word length and sentence length) and then evaluate both parts for readability. Ideally, all parts of a piece of content should be written at a ninth-grade reading level. This ensures that the content will be easy for virtually everyone to understand and that technical manuals, insurance policies and medical documents are not out of reach of the common reader.

There are two parts to the Flesch-Kincaid readability tests: The Flesch reading ease test and the Flesch-Kincaid grade level test. They both measure word and sentence length and their results relate conversely to one another. For example, if a piece of text has a high Reading Ease score, it should have a low grade level score.

The Flesch reading ease test

When a piece is evaluated with the Flesch reading-ease test, the higher the score, the better.

The formula for this test is as follows:

206.835 – 1.015 (total words/total sentences) – 84.6 (total syllables/total words).

The score breakdown is as follows:

  • 0-30: understood easily by university graduates

  • 60-70: easily understood by 15 year-old students

  • 90-100: easily understood by most 11 year-old students

Reader’s Digest, for example, is a 65 on the readability index while Time is a 52. The highest possible readability score is around 120 and consists of easy words, monosyllabic words and sentences like “the dog chased the frog.”

The Flesch-Kincaid grade level test

These tests are popular in the education field and present a piece of text based upon its readability for a US grade level. This makes it easy for adults to judge immediately the difficulty or ease of a piece and to ascertain its suitability for certain groups. Additionally, this test helps ascertain how many years of education a person needs to have in order to read a piece of content. The formula for this test is as follows:

0.39 (total words/total sentences) + 11.8 (total syllables/total words) – 15.59

Writing Content for the Flesch-Kincaid Tests: 4 key Tips

Now that you understand what the tests are, it’s time to talk about how you can write content that adheres to their formulas. This is important because, when content is simple to read, it’s more likely to grab a reader and maintain interest. Additionally, all great business writing is simple, clear, and to-the-point. This cuts away the amount of muck a reader has to wade through and makes it easy to get to the heart of the content.

To write great content that gets good scores on the readability tests, follow these 4 tips:

  1. Keep sentences per paragraph low: Nobody wants to wade into a never-ending paragraph. In addition to being ugly, these paragraphs are tough to read and, as such, they’ll earn you a low readability score. To keep readability up, break your text into nice, neat paragraphs rather than huge blocks of content.

  2. Keep words per sentence low: Run-ons, be gone! To keep your readability score high, use no more than 25 words per sentence you write. This keeps our subject clear and makes your writing easy to read. This also allows you to separate your thoughts and allow your readers to breathe before you leap between ideas.

  3. Keep character per word counts low: Unless you’re writing a technical piece, keep your words simple. For example, use “went” instead of “intended to go to.” This makes your text more readable and inherently makes it easier for readers to discern the meaning of it.

  4. Do away with passive voice: Passive voice is the silent enemy of writers everywhere and, in addition to being annoying, it makes writing confusing. “The apple was being eaten” doesn’t make nearly as much sense as “Sam ate the apple.” Keep your writing clear by writing in active rather than passive voice.

Testing your readability

If you write in Microsoft word, you’ve already got a valuable readability evaluator you probably didn’t even know about. To tap into it, run the typical “spelling & grammar” check from your toolbar.

From here, click the “options” button at the bottom of your screen and check the box that says “show readability statistics.”

This will magically give you all of the stats you need to boost your readability score. Including sentence per paragraph, words per sentence and characters per word sentence. It will also give you your passive sentence percentage and both your Flesch reading ease and Flesch-Kincaid grade level scores.

How Readability Affects SEO

By now, we all know that good SEO means great content – content that is easy for search engines and people to locate and read. Additionally, since simple content allows readers to scan quickly and find answers, it’s generally preferred by SEO. Therefore, writing that falls within desirable Flesch-Kincaid scores can be more desirable to SEO and easier for readers to find and love.

Although most writers are unfamiliar with the Flesch-Kincaid readability tests, tapping into the power of these simple metrics can help you improve your writing and deliver clearer content for your readers.


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