About Readability

Readability refers to certain qualities of written text, with respect to being legible/decipherable and/or easy/enjoyable to read. A comprehensive definition of readability, although referring to printed materials it is still applicable to text in any format, has been given by Edgar Dale and Jeanne Chall (1949):

“The sum total (including all the interactions) of all those elements within a given piece of printed material that affect the success a group of readers have with it. The success is the extent to which they understand it, read it at an optimal speed, and find it interesting.”

When designing a website or trying to share/convey information in written format, it is important to make sure that the presentation style (e.g. length of sentences, grammar, difficulty of words) is not a barrier. On the other side, texts that are too easy to read may fail to engage the reader because they are boring.

Selected Readability References

  1. The Principles of Readability. Impact Information.
    • DyBay, W.H., (2004). Url:
  2. Writing for Every Reader.
    • Hobson, S. – Url:
  3. Readable: What is Readability?
    • – Url:
  4. Ultimate guide to blog readability.
    • Barron, B. –Url:
  5. Design guidelines for web readability. Proceedings of the 2017 Conference on Designing Interactive Systems,
  6. Contextual web accessibility - maximizing the benefit of accessibility guidelines
    • David Sloan, Andy Heath, Fraser Hamilton, Brian Kelly, Helen Petrie, Lawrie Phipps.
  7. Some guidelines for creating World Wide Web home page files
    • Pieter A. van Brakel, Cerina Roeloffee, Amanda van Heerden.
  8. Web style guide
    • Patrick J Lynch.
  9. Are guidelines enough? An introduction to designing Web sites accessible to older people
    • S. Milne ; A. Dickinson ; A. Carmichael ; D. Sloan ; R. Eisma ; P. Gregor.
  10. style guide
  11. SIGACCESS style guide
  12. Can readability formulas be used to successfully gauge difficulty of reading materials?
    • Begeny, J.C., Greene, D.J. (2013). Psychology in the Schools, Wiley Periodicals. Doi: 10.1002/pits.21740.
  13. A comparison of features for automatic readability assessment.
    • Feng, L., Jansche, M., Huenerfauth, M., Elhadad, N. (2010). Proceedings of the 23rd International Conference on Computational Linguistics, pp. 276-281.

Video explanation of readability:

Readability Score Tools

A readability score is a computer-calculated index indicating the level of education a reader should have in order to understand the written text being assessed. Readability scores, in addition to pointing out problems, are also providing tools to solve readability issues. A number of formulas are used to measure readability, some of them providing the output in the form of a score (e.g. Flesch-Kincaid Reading Ease, Spache Score, New Dale-Chall Score) which needs to be interpreted, while some other provide directly the readability grade levels (e.g. Flesch-Kincaid Grade Level, Gunning-Fog Score, Coleman-Liau Index, SMOG Index, Automated Readability Index). Various free online tools have been implemented to automatically calculate readability and to analyze text clarity and content: