Clarity of communication is essential. Whether you’re creating user manuals, technical documentation, or marketing content, ensuring that your audience can easily understand your material is crucial. In this article, we’ll explore why readability matters, how the Flesch-Kincaid Grade Level works, and how you can use readability metrics to improve your documentation.
What Is the Flesch-Kincaid Grade Level?
The Flesch-Kincaid Grade Level is a readability metric designed to assess the complexity of English texts. It provides a score that corresponds to a U.S. school grade level, helping writers gauge the education level required for readers to understand their material. This metric is particularly useful for ensuring that documentation is accessible to a broad audience.
What Is a Flesch Reading Ease Score?
The Flesch Reading Ease Score is another readability measure that evaluates how easy a text is to understand. It assigns a numerical score from 0 to 100, with higher scores indicating simpler, more readable content.
- 90–100: Very easy to read (suitable for young children).
- 60–89: Standard readability (understandable by most teenagers and adults).
- 30–59: Difficult to read (better suited for college-level readers).
- 0–29: Very difficult (appropriate for technical or academic texts).
The formula for calculating the Flesch Reading Ease Score is:
RE = 206.835 - (1.015 x Total Words / Total Sentences) - (84.6 x Total Syllables / Total Words)A higher score suggests shorter sentences and simpler vocabulary, making the text more accessible.
Flesch-Kincaid Grade Level Table
| Flesch-KincaidGrade Level | Corresponding School Grade | Description |
| 0-1 | Pre-K to 1st Grade | Very simple texts, suitable for young children. |
| 2-3 | 2nd to 3rd Grade | Simple sentences and vocabulary, ideal for early readers. |
| 4-5 | 4th to 5th Grade | Basic texts suitable for middle elementary students. |
| 6-7 | 6th to 7th Grade | Intermediate complexity, appropriate for late elementary to early middle school. |
| 8-9 | 8th to 9th Grade | More complex texts, suitable for middle school students. |
| 10-12 | 10th to 12th Grade | Advanced texts, appropriate for high school students. |
| 13+ | College Level | Complex academic or professional texts, suitable for college students and adults. |
This table helps illustrate the relationship between Flesch-Kincaid Grade Level scores and educational levels, making it easier to identify the intended audience for different types of writing. By aiming for an appropriate grade level, writers can ensure their documentation is clear and accessible to their target readers.
How Do Flesch Tests Work
The Flesch-Kincaid readability tests evaluate text complexity based on sentence length and word difficulty (measured by syllables). While the Flesch Reading Ease Score provides a general readability rating, the Flesch-Kincaid Grade Level translates this into a school grade level.
These tests are useful for ensuring documents are accessible to the intended audience. For example:
- A technical manual should aim for a higher grade level to match its professional audience.
- Marketing content or user guides should have a lower grade level for broad accessibility.
By applying Flesch readability metrics, writers can refine their content for clarity and engagement.
How Flesch-Kincaid Grade Level Works
The Flesch-Kincaid Grade Level is one of the most widely used readability tests for determining the complexity of written content. It calculates a score that corresponds to a U.S. school grade level, indicating the minimum education level needed to comprehend the text.
Formula for Calculating the Flesch-Kincaid Grade Level
GradeLevel = (0.39 x Total Words / Total Sentences) + (11.8 x Total Syllables / Total Words) – 15.59
Key Components of the Formula:
- Total Words: The number of words in the text.
- Total Sentences: The number of sentences in the text.
- Total Syllables: The total number of syllables in all words.
The lower the grade level, the simpler the readability, making the text more accessible to a wider audience. For instance, a score of 8 means an eighth grader should be able to comprehend the text.
Flesch-Kincaid in Practice: Understanding Book Readability
The Flesch-Kincaid Grade Level index corresponds closely with the classification system used in the bookseller industry. While booksellers categorize books by age range rather than grade level, there is a strong overlap:
- Early Reader (Grades 1–3): Simple vocabulary and short sentences (Goosebumps, Magic Tree House).
- Middle Grade (Grades 4–8): More complex language with moderate sentence length (Harry Potter, The Hobbit, Roald Dahl’s books).
- Young Adult (YA – Teenagers): Writing style similar to adult fiction, sometimes with mature themes (The Hunger Games, John Green novels, Twilight).
However, every child has a unique reading level, which may not align perfectly with their grade. A 3rd grader might read early readers, while a 7th grader might prefer YA novels. Instead of rigidly classifying content, it’s best to consider who your audience is and adjust accordingly.
Key Differences in Book Categories
- Early Reader: Short books with simple language and child-friendly topics (minimal or no violence, no mature themes).
- Middle Grade (MG): More advanced language, but still simpler than adult books. Some violence is allowed but remains mild.
- Young Adult (YA): Writing style matches adult books; violence and mature themes (including romance) are allowed, but characters must be teenagers.
Writers should focus on making content accessible while maintaining the appropriate level of complexity for their intended readers.
Drawbacks of Readability Indexes
There is some misunderstanding around “readability levels.” It is often considered a blunt tool that measures sentence length and structure against the use of unfamiliar or long words. However, it cannot assess the content of your writing—such as the maturity of your themes. For instance, you could write a story about murder, love, and death, and if you use short, clear sentences, you could still achieve a low readability grade.
For example, if your writing scores at Grade 4, this simply means it’s easy to read. It doesn’t imply the content is overly simplified or intended for children. If you were to rewrite the text to increase its grade level, you’d be deliberately making it more complex and less accessible.
In fields like marketing, copywriting, or technical writing, it is generally assumed that the writer should aim to make their content as easy to read and as human-friendly as possible. For professionals with a background in marketing, PR, freelance journalism, or tech writing, readability often equates to quality. In fact, much of technical writing involves translating complex, academic-level texts into content that can be understood at a Grade 7–8 reading level, without losing essential meaning.
Why Is Your Documentation So Hard to Read?
Your product may include all the necessary help docs covering all bottlenecks and offering very detailed ways of troubleshooting. Still, users would prefer to contact your customer service instead of reading the FAQ section.
There may be different reasons why your technical documentation is so unpopular among readers. The most obvious are the following:
- Technical jargon. For example, if you write “CanCycle” which is a shortened form of ‘canned cycle’ meaning ‘a ready-made program cycle or set of steps to follow’ (a coined jargon word in an operation manual for a CNC lathe machine), 99 out of 100 of your readers will have problems with understanding this. So, make sure jargon words are avoided. It doesn’t matter if they are popular in your company and understood by everyone in the industry. They may be like ‘mother’s milk’ to you and a real headache for your readers and customers who want to hear normal human language.
- Technical terms. Another thing that may discourage users is the large number of terms used in your technical documentation. Terms are usually split into commonly known and rare terms. By way of example, in the field of IT, a ‘file manager’ is a commonly known term, while such words as ‘bus’ or ‘TCP’ refer to the category of rare or just unknown words for some people. This is why it is important to avoid terms. If this is impossible, make sure they are properly explained.
- Long words. Of course, this is very different in different languages. For French, three-syllable words are all right, while in German, a single word can be a line long. In English, one- and two-syllable words make the core of the vocabulary. So, if you write technical documents in English, make sure three- and four-syllable words are not too many. They may hinder comprehension not only because of the length but also because they are mostly borrowed into English from other languages (mostly French and Latin). A foreign origin is often totally forgotten, but some words are still perceived as foreign and require additional effort from the reader, for example, consulting a dictionary. You just have to bear it in mind in the process of content creation.
- Complex sentences. This is another problem that may hinder communication with customers. Complex sentences (aka ‘long’ sentences) are often hard to understand because, when the reader finally reaches the end of the sentence, the beginning is usually forgotten. So, don’t try to pack all information in one sentence. You will make it lengthy and overloaded with messages. Follow the KISS formula – keep it short and simple.
Most readability indices will help you identify long words and sentences. This will help you change your documentation so that reading will go smoothly. Ultimately, it will help to improve the UX parameters of your technical content.
The Most Popular Readability Indexes
All readability indices can be split into three groups according to the three principles they are based on. These principles are the ways the text is analyzed.
Group 1. Most indices (Flesch-Kincaid Grade Level, Flesch Reading Ease, Gunning Fog, etc.) are based on the analysis of the length of words and sentences. The longer the words and sentences, the higher the text complexity is, and the more difficult the text is to read and comprehend.
The indices in this group provide their own assessment scales that help pin the text on the ‘readability map.’ Each analyzed text gets its own readability score that puts it on a specific readability level.
The levels are tied to the US education system. That is why you can see such levels as a pre-kindergarten, 1st-5th grade, and the following grades covering all years of study from elementary to high school.
The assessment scale is the only difference between these indices. In a way, each scale reflects a subjective view of its developer on the readability issue. That is why the index often bears the name of its author, like Flesch-Kincaid, Gunning Fog, Coleman-Liau, etc.
Group 2. The indices here are based on syllable count instead of word count, as in the group above. The brightest examples are the SMOG index and the Forcast Grade. The principle of syllable count is the same in both cases, but the methods are different.
The SMOG Index focuses on the count of words with three or more syllables. Such words are considered long for the English language, and, as was said above, such words are regarded as foreign and require higher reading-comprehension skills from users. The number of such words is analyzed in a sample text fragment containing at least 30 sentences.
The FORCAST Grade uses an opposite approach. It is focused on the count of one-syllable words, which are considered easy to understand. This thesis is very contestable, though, because if you look at a dictionary entry for any one-syllable word, you will find that these are polysemantic words (have lots of different meanings). This can hinder understanding dramatically. Still, the FORCAST Grade is widely used as a readability metric for analyzing sample text fragments containing 100-150 words.
Group 3. Group 3 can be called ‘Miscellaneous,’ as it contains metrics based on separate original methods that cannot be grouped with others. For example, the Time to Read metric is based on the time factor. It allows you to estimate the approximate time a user will take to read the text. The longer it takes, the more complex the text is for comprehension and the lower its readability.
Another example in the Miscellaneous group is the New Dale-Chall metric. The text analysis is based on a predefined set of “common” words and the ratio of “difficult” words and words per sentence. The more common words the text contains, the higher its readability.
No matter what metric you choose, it will improve your documentation greatly. With the help of readability metrics, you will have a chance to look at your documentation with the eyes of your users or potential customers. What’s more important, you will be able to transform your content so that its user experience parameters will be enhanced.
Readability Metrics in ClickHelp
ClickHelp is an online platform for managing content that provides users with a whole arsenal of tools to produce effective technical documentation with minimum effort, time, and cost.
It is built on the principles of content reuse and single sourcing, meaning that new documentation can be derived from previously created content. However, during the process of reviewing, editing, adding, or deleting content, it might lose its original focus. Texts can become overloaded with new information that needs to be added each time your product is updated. This can negatively impact the SEO and UX aspects of your content.
To avoid this, ClickHelp offers a set of metrics that can be used to analyze content in terms of readability. The metrics available in ClickHelp cover all the indices mentioned above and even more.
In addition to the methods already described in the blog, ClickHelp offers Automated Readability Index focused on the count of letters per word and words per sentence (which is more accurate than the count of characters as in the Coleman-Liau index). Another addition is the Linsear Write formula based on the number of words with three or more syllables in a sample of text containing at least 100 words.
What’s more, ClickHelp offers the Average Grade metric, which is an arithmetic mean of all readability metrics available on the platform. The Average Grade metric will help you make your content ideal for average readers using the accumulated results of all the metrics mentioned above.
Conclusion
User experience is an important factor that can influence the popularity of your product on the market. UX includes not only the navigability of your product but also how easy or hard it is to find the necessary solution. To help readers find the right answers to their questions, tech writers and developers provide users with supporting technical documentation.
This content is another element that contributes to the user experience. Documentation greatly impacts the impression your product produces on the users. If it is full of technical terms, jargon, and complex sentences, the user experience will be low.
To avoid this, ClickHelp offers its users a set of readability metrics. They will help to enhance the overall quality of your content and bring your documentation to a whole new level.
Good luck with your technical writing!
ClickHelp Team
Author, host and deliver documentation across platforms and devices
