What is the Bormuth Readability Index?

Although there are several readability tests out there, one of the underlying features that all of them have in common is the ability to assign a specific level of difficulty (or grade level) to a text in order to determine its difficulty and complexity. The Bormuth readability index is one such test. The Bormuth Readability Index (also called the Bormuth Formula) assigns a grade level to text based on character count and average number of familiar words. Unlike other readability formulas like Flesch Kincaid which focus on syllable count, Bormuth relies on a word list from the Dale-Chall readability formula. In order to understand how the Bormuth Readability Inde works, it’s important to touch on how the Dale-Chall formula works.

The Origins of the Dale-Chall Reading Formula

Developed by Edgar Dale, an education professor at Ohio State University, and Jeanne Chall, the director of the Harvard Reading Library (and reading consultant for shows like Sesame Street), the two were inspired by the Flesch reading formula to change how readability is measured. 

Unlike Flesch Kincaid or other readability formulas at the time, Dale-Chall measures what it considers “hard words’. Originally when the formula was created and published in 1948, there were over 700 words that were recognizable  based on the average reading ability of a fourth grader. Dale-Chall’s word list was updated in 1995 to expand the list to 3000 words. The new Dale-Chall formula is based on the use of familiar words rather than how many syllables or letters a word has.

What Does That Have to Do With The Bormuth Formula?

Simply put, the Bormuth formula uses the average number of familiar words (based on Dale-Chall’s list) as part of its calculation, along with number of characters. Bormuth calculates the average of familiar words in a text rather than concentrating on hard words, like the original Dale-Chall readability formula did. 

Who Invented the Bormuth Readability Formula and Why?

The Bormuth readability formula was developed by John R. Bormuth of the University of Chicago in order to evaluate textbooks. However, given that it uses Dale-Chall’s word list (which was designed for a fourth-grade level), the Bormuth readability formula only works accurately at this level or above. 

If you’re looking to test the readability of your content using the Bormuth formula, you’ll find that it outputs an approximate grade level based on the formula. So a score of 11.0 would mean that your content is readable by a student in the 11th grade or higher.

Testing the Readability of Your Content with Originality.AI 

If you’re interested in testing how readable your content is whether online or in preparation for publication, you’ll want to check out Originality.AI’s new readability checker. Rather than scanning your content for readability based on a single readability formula, like Flesch Kincaid or the Gunning Fog Index, it checks the readability of your content using a wide range of different formulas and angles, so that you get the full picture of how understandable your content truly is. 

Using Originality.AI’s free readability checker, you can get a quick and easy Flesch Kincaid readability score, as well as a score on how readable your content is according to formulas like:

  • Gunning Fog Index
  • FORCAST grade level
  • SMOG index
  • Powers Sumner-Kearl
  • Coleman-Liau index
  • Automated Readability Index
  • Dale-Chall Readability
  • Spache Readability
  • Linear Write Grade

You’ll also be able to use the readability tool to determine the average syllables per word, average sentences per paragraph, words with more than 12 letters or words with more than four syllables among others.

The Originality.AI readability checker also gives you some fascinating statistics about your text, including character count and word count, sentence count, syllable count and the longest sentence in the piece.

And last but certainly not least, if you’re optimizing your content for the search engines, you can check the keyword density either in terms of single keywords or double keywords (keyphrases). This makes it an easy and highly effective tool for search engine experts as well as content writers, copywriters and publishers who want to ensure their content is readable and understandable by their target audience. 

And did we mention that the readability test is free to use? Because it is. However, beyond the free readability checker is a much more in-depth scanning process that also checks your writing for plagiarism and AI writing, helping you avoid incorrect references or citations and avoid publishing any content that has the tell-tale hallmarks of being written by AI like ChatGPT or Bard. Try Originality.AI’s readability checker now! 

All Readability Tests:

Here is a list of all readability tests.

Sherice Jacob

Plagiarism Expert Sherice Jacob brings over 20 years of experience to digital marketing as a copywriter and content creator. With a finger on the pulse of AI and its developments, she works extensively with to help businesses and publishers get the best returns from their Content.

More From The Blog

AI Content Detector & Plagiarism Checker for Serious Content Publishers

Improve your content quality by accurately detecting duplicate content and artificially generated text.