Flesch readability scores are the most used and trusted of all readability scoring formula. But, what actually are the Flesch and Flesch-Kincaid readability scores? And what do the scores really mean?
What is a Flesch Reading Ease score?
In the late forties, Rudolph Flesch was a consultant with the Associated Press, developing methods for improving the readability of newspapers.
From this work, the Flesch Reading Ease (1948) was born.
The new and innovative readability test could tell you what level of education someone needed to easily read a piece of text.
This was done by giving the text a score of between 1 and 100.
Scoring between 70 to 80 is equivalent to school grade level 8, meaning text should be fairly easy for the average adult to read.
Now, over 70 years later, the Flesch Reading Ease is used by marketers, research communicators and policy writers, amongst many others.
All use it to help them assess the ease by which a piece of text will be understood and engaged with.
And what about the Flesch-Kincaid Grade Level?
A challenge in using the Flesch Reading Ease is that test results are not immediately meaningful.
A conversion table is needed to make sense of the score, which isn’t ideal when you need to get things done quickly.
To fix this, the US Navy revisited the Flesch Reading Ease in the mid-70s and amended the formula to make it easier to use.
The Navy used the new Flesch-Kincaid Grade formula to measure the difficulty of technical manuals used in training.
Now, that’s a collection of text that definitely needs to be easy to understand!
With the Flesch-Kincaid Grade Level, if a piece of text has a grade level readability score of 8, this means the average reader has to have a grade 8 level of reading, or above, to understand it.
How do the tests work?
The mathematical formula underlying the two tests look like this:
If you’re like me, mathematical formula can make you run for the hills.
But, the building bricks that make up both formula are straightforward and based on two factors:
- Sentence length. As judged by the average number of words in a sentence
- Word length. As judged by the average number of syllables in a word
The rationale here is straightforward. Sentences that contain a lot of words are more difficult to follow than shorter sentences.
Just read James Joyce's Ulysses to see what I’m talking about.
Similarly, words that contain a lot of syllables are harder to read than words that use fewer syllables.
For example, "it was a lackadaisical attempt" is more difficult to read than "it was a lazy attempt".
Making sense of the results
To recap, both the Flesch Reading Ease and Flesch-Kincaid Grade Level tests are calculated on the same units.
But, the weightings differ between formulas, resulting in different readability scores for each test.
Flesch-Kincaid Reading Ease. The higher the reading score, the easier a piece of text is to read.
Note that this differs from the majority of readability scores where a lower score is easier.
For example, a reading score of 60 to 70 is equivalent to a grade level of 8-9 so a text with this score should be understood by 13 to 15-year-olds.
To make sense of a Reading Ease score a conversion table is needed to translate the score into a grade level.
Flesch-Kincaid Grade Level. The score generated by the Flesch-Kincaid Grade Level is equivalent to the US grade level of education that the reader would require to be able to understand that piece of text.
Text intended for readership by the general public should aim for a grade level of around 8, schooling age 13 to 14.
When is Flesch-Kincaid most useful?
Flesch-Kincaid readability tests are useful any time you want to quickly measure how easily people can understand a piece of text.
This makes it ideal for:
- Writing copy for your website
- Advertising your product
- Producing terms and conditions that don’t confuse
- Boosting your SEO performance
- Choosing textbooks for a class or training program
- Editing your novel
- Communicating your research to a non-specialist audience
Whatever you are writing, readability scores can give you valuable insights into how easy your text is to understand by your intended reader.
This has a direct impact on the extent people engage with and take on your message.
Content with a higher engagement rate has many benefits, including:
- Decreasing bounce rate
- Increasing time on site
- Content delivers for the reader
- Readers want to share your content
- Readers go further into your site
- They also
- Click on call to actions
- Add products to their shopping carts
- Spend money with you
- Keep on coming back
Having a readable website with engaging content is a boost for any business or organization.
How do the Flesch tests compare to other readability formulas?
With over 200 readability formulas to choose from, you can drown in the options that are available to you.
Here are just some examples:
- Flesch-Kincaid Grade Level - good for all sectors and disciplines
- Gunning Fog Index - aimed at businesses
- Coleman Liau Index - widely used and has found a home in the medical and translation sectors
- SMOG Index - considered the 'gold standard' formula in healthcare
- Automated Readability Index - technical writing
- FORCAST - particularly useful for surveys, questionnaires, multiple question tests or any document containing lists or bullet points
- Powers Sumner Kearl - suited for elementary text, but not for text above a fourth-grade level
- Lix Readability - suitable for use with both English and non-English texts
- Rix Readability - an alternative to Lix
- Raygor Readability Graph - best used for middle school level texts
- Fry Readability Graph - for elementary to college level texts
- CEFR - used by schools, workplaces and governments to ensure their content is reaching a wide audience
- IELTS - used to make your content inclusive and accessible
- Spache Readability Formula - created for use in elementary schools
- Dale-Chall Readability Formula - created for use by fourth-grade students or higher within an elementary school
- Lensear Write - a solution to stuffy 'governmentese' or 'officialese’
For a more detailed description, take a look at our readability formula page.
ReadablePro, a fantastic SEO tool for creating readable content
The complexity and number of readability formula are one of the reasons we created Readable.
We wanted to develop a tool that included the complicated formula above and was easy to use.
To make understanding the collection of readability scores nice and clear, we’ve taken it one step further and developed our own unique readability rating of A, B, C, D or E.
An A is the best rating.
We’ll also show you a host of readability info, such as:
- The score or reading level of your content, individual URLs and whole websites
- Where you need to refine your content
- Spelling and grammar errors
- Analytics and text statistics – letter, word and syllable counts
- Composition stats – adjective, noun and adverb counts
- Keyword density
- Reading and speaking time
- Sentiment analysis – is the text positive, negative or neutral?