What Is Readability?

Readability refers to the ease with which text can be read and understood. Readability formulas are often used to assess the difficulty of text. These formulas use mathematical calculations to produce a score. The score shows the relative difficulty on a continuum from easy (grade five or lower) to very hard (college level and above). Higher scores mean lower reading ease or lower readability.

Readability formulas measure two factors: the average length of words and the average length of sentences. These two factors have been known for decades to be the factors that contribute most to the difficulty of text.

A readability score is given as a “grade level,” but there is no direct correspondence between an individual’s level of education and their ability to read text at a particular grade level. Readability scores are best used to assess whether your text is written at an appropriate level for your intended audience.

Testing reading level is an essential step before conducting field testing on any document. We recommend working with members of the intended audiences throughout the development process. Readability testing is not meant to replace field testing, but it is an important step in preparing for field testing.

It is important to remember there are also many other factors that influence the overall reading ease and understandability of text-based information. Some examples of the other factors are: organization of information, graphic design, typesetting, visuals, and cultural relevance. In creating materials, we keep all these factors in mind.

Why Is Readability Important?

Knowing the reading level of your text can give you a general idea how many people may be able to read it. The most recent national assessment of adult literacy showed that 43% of adults living in the U.S., some 93 million people, have Basic or Below Basic literacy skills.1

For audiences with limited literacy skills, or those in population groups shown to be at risk of limited literacy,1 text should be written at the 6th grade level or lower. For the general public, text should be written at the 8th grade level or lower. Some people worry that 8th grade level text will offend highly skilled readers. However, most people are pressed for time and may be stressed when reading health information so they appreciate quick, concise information written in everyday language.2

This means it’s important to write clearly, concisely, and without jargon or difficult words if you hope to reach people who do not read easily and even those who do. (Think, “Call your doctor if you have…” versus “Contact your physician if you experience…”)

Be Careful with Readability in Word Processing Programs

You may have discovered that popular word processing programs have readability functions. Readability tools may be fast and convenient, but they can give inaccurate results.

Before using these programs, you need to know:

  • How to prepare your text before analyzing the reading level
  • Which software program or website is valid and reliable for your type of document
  • Which formulas are valid and reliable for your type of document
  • How to interpret the results

Our Readability Services

The Clear Language Group can provide:

  • Readability analysis of your text
  • Comprehensive reports of recommendations to improve the reading ease of your materials
  • Consultations and short workshops on how to accurately and quickly analyze reading level on your own



  1. Kutner M, Greenberg E, Baer J. National Assessment of Adult Literacy (NAAL): A First Look at the Literacy of America’s Adults in the 21st Century (NCES 2006-470). Washington, DC: National Center for Education Statistics; 2005.
  2. Kimble J. Writing for Dollars, Writing to Please: The Case for Plain Language in Business, Government, and Law. Durham, NC: Carolina Academic Press; 2012.