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Reading Level:
Understanding SC 3.1.5

3.1.5 Reading Level: When text requires reading ability more advanced than the lower secondary education level, supplemental content or [begin add]a version[end add] [begin delete]an alternate version is available[end delete] that does not require reading ability more advanced than the lower secondary education level [begin add]is available[end add]. (Level AAA)

Intent of this Success Criterion

Content should be written as clearly and simply as possible. The intent of this success criterion is:

This success criterion helps people with reading disabilities while also allowing authors to publish difficult or complex Web content. Text difficulty is described in terms of the level of education required to read the text. Education levels are defined according to the International Standard Classification of Education [UNESCO], which was created to allow international comparison among systems of education.

Difficult or complex text may be appropriate for most members of the intended audience (that is, most of the people for whom the content has been created). But there are people with disabilities, including reading disabilities, even among highly educated users with specialized knowledge of the subject matter. It may be possible to accommodate these users by making the text more readable. If the text cannot be made more readable, then supplemental content is needed. Supplemental content is required when text demands reading ability more advanced than the lower secondary education level—that is, more than nine years of school. Such text presents severe obstacles to people with reading disabilities and is considered difficult even for people without disabilities who have completed upper secondary education.

Reading disabilities such as dyslexia make it difficult to recognize written or printed words and associate them with the correct sounds. This is called "decoding" the text. Decoding must be automatic in order for people to read fluently. The act of decoding text word by word consumes much of the mental energy that most people are able to use for understanding what they read. Text that uses short, common words and short sentences is easier to decode and usually requires less advanced reading ability than text that uses long sentences and long or unfamiliar words.

The education level required to read text content (also called "readability") is measured by analyzing selected passages of text from the Web page. If the Web page includes text written for different purposes or different styles are used, the selected passages include samples of the types of content in the Web page and the different styles in which the content is written. (In many cases, the Web page contains only one kind of text content—e.g., technical documentation, a legal notice, marketing material, etc.—and all the content uses the same style.)

Educators can also measure the education level required to read text content. For example, qualified teachers can evaluate text according to local education standards to determine if it requires reading ability beyond what is expected for students in the last year of lower secondary education.

When a web page contains multiple languages, a readability result should be calculated for each language that constitutes at least 5% of the content and that is used in full sentences or paragraphs (not just individual words or phrases). The overall readability of the page should be judged on the language that yields the worst readability results.

The readability of content may also be determined by applying a readability formula to the selected passage. Many (though not all) readability formulas base their calculations on passages of 100 words. Such formulas have been developed for many languages. The number of words in the passage is counted and the length of the words is determined by counting either the number of syllables or the number of characters. Most readability formulas also count the number and length of sentences. The average length of words and sentences in the content is then used to calculate a readability score. (Some languages, such as Japanese, may include multiple scripts within the same passage. Readability formulas for these languages may use the number and length of such "runs" in their calculations.) The result may be presented as a number (for example, on a scale from 0-100) or as a grade level. These results can then be interpreted using the education levels described in the International Standard Classification of Education. [begin add]Readability formulas are available for at least some languages when running the spell checkers in popular software if you specify in the options of this engine that you want to have the statistics when it has finished checking your documents. [2162] [end add]

Levels of education
Primary education Lower secondary education Upper secondary education Advanced education
First 6 years of school7-9 years of school10-12 years of schoolMore than 12 years of school

Adapted from International Standard Classification of Education [UNESCO]

[begin add]

Note: According to the Open Society Mental Health Initiative, the concept of Easy to Read cannot be universal, and it will not be possible to write a text that will suit the abilities of all people with literacy and comprehension problems. Using the clearest and simplest language appropriate is highly desirable, but the WCAG Working Group could not find a way to test whether this had been achieved. The use of reading level is a way to introduce testability into a success criterion that encourages clear writing. Supplementary content can be a powerful technique for people with some classes of cognitive disability. [2257]

[end add]

Specific Benefits of Success Criterion 3.1.5:

This success criterion may help people who:

  • Have difficulty comprehending and interpreting written language (e.g. articles, instructions, or newspapers in text or braille), for the purpose of obtaining general knowledge or specific information

Examples of Success Criterion 3.1.5

  1. A scientific journal including readable summaries of complex research articles

    A scientific journal includes articles written in highly technical language aimed at specialists in the field. The journal's Table of Contents page includes a plain-language summary of each article. The summaries are intended for a general audience with eight years of school. The metadata for the journal uses the Dublin Core specification to identify the education level of the articles' intended audience as "advanced," and the education level of the intended audience for the summaries as "lower secondary education."

  2. Medical information for members of the public.

    A medical school operates a Web site that explains recent medical and scientific discoveries. The articles on the site are written for people without medical training. Each article uses the Dublin Core metadata specification to identify the education level of the intended audience as "lower secondary education" and includes the Flesch Reading Ease score for the article. A link on each page displays the education level and other metadata. No supplemental content is required because people who read at the lower secondary education level can read the articles.

  3. An e-learning application.

    An on-line course about Spanish cultural history includes a unit on Moorish architecture. The unit includes text written for students with different reading abilities. Photographs and drawings of buildings illustrate architectural concepts and styles. Graphic organizers are used to illustrate complex relationships, and an audio version using synthetic speech is available. The metadata for each version describes the academic level of the content and includes a readability score based on formulas developed for Spanish-language text. The learning application uses this metadata and metadata about the students to provide versions of instructional content that match the needs of individual students.

  4. [begin delete]

    Science information that requires a reading ability at the lower secondary education level.

    [end delete]
    [begin delete]

    The paragraphs below (114 words total) require a reading ability of grade 6.9 in the United States according to the Flesch-Kinkaid formula. In the US, grade 6.9 is at the lower secondary education level.

    [end delete]
    [begin delete]

    In a dazzling and dramatic portrait painted by the Sun, the long thin shadows of Saturn's rings sweep across the planet's northern latitudes. Within the shadows, bright bands represent areas where the ring material is less dense, while dark strips and wave patterns reveal areas of denser material.

    [end delete]
    [begin delete]

    The shadow darkens sharply near upper right, corresponding to the boundary of the thin C ring with the denser B ring. A wide-field, natural color view of these shadows can be seen here.

    [end delete]
    [begin delete]

    The globe of Saturn's moon Mimas (398 kilometers, or 247 miles across) has wandered into view near the bottom of the frame. A few of the large craters on this small moon are visible.

    [end delete]
    [begin delete]

    (Source: NASA - Sun-striped Saturn)

    [end delete]
  5. [begin add]

    Science information that requires a reading ability at the lower secondary education level.

    [end add]
    [begin add]

    The text below (116 words total) requires a reading ability of grade 4.2 in the United States according to the Flesch-Kinkaid formula. In the US, grade 4.2 is at the primary education level.

    [end add]
    [begin add]

    Science is about testing — and about looking closely. Some scientists use microscopes to take a close look. We're going to use a simple piece of paper.

    [end add]
    [begin add]

    Here's what you do: Print this page and cut out the square to make a "window" one inch square. (It's easiest to fold the page in half before you cut.)

    [end add]
    [begin add]

    Choose something interesting: a tree trunk, a leaf, flower, the soil surface, or a slice of soil from a shovel.

    [end add]
    [begin add]

    Put your window over the thing and look at it closely. Take your time — this is not a race.

    [end add]
    [begin add]

    To help you see more details, draw a picture of what's inside your square.

    [end add]
    [begin add]

    Now let's think about what you've found.

    [end add]
    [begin add]

    (Source: Howard Hughes Medical Institute [2161]

    [end add]

Related Resources

Resources are for information purposes only, no endorsement implied.

Techniques and Failures for Success Criterion 3.1.5 [Reading Level]

Each numbered item in this section represents a technique or combination of techniques that the WCAG Working Group deems sufficient for meeting this success criterion. The techniques listed only satisfy the success criterion if all of the WCAG 2.0 conformance requirements have been met.

Sufficient Techniques

  1. G86: Providing a text summary that requires reading ability less advanced than the upper secondary education level

  2. G103: Providing visual illustrations, pictures, and symbols to help explain ideas, events, and processes [2159]

  3. G79: Providing a spoken version of the text

  4. Making the text easier to read (future link)

  5. Providing sign language versions of information, ideas, and processes that must be understood in order to use the content (future link)

Note: Different sites may address this success criterion in different ways. An audio version of the content may be helpful to some users. [begin delete]But if a site is intended for individuals who are deaf, providing an audio file would not be useful. [1983] [end delete]For some people who are deaf, a sign language version of the page may be easier to understand than a written language version since sign language may be their first language. Some sites may decide to do both or other combinations. No technique will help all users who have difficulty. So different techniques are provided as sufficient techniques here for authors trying to make their sites more accessible. Any numbered technique or combination above can be used by a particular site and it is considered sufficient by the Working Group.

Additional Techniques (Advisory)

Although not required for conformance, the following additional techniques should be considered in order to make content more accessible. Not all techniques can be used or would be effective in all situations.

Metadata Techniques
  • Using metadata to associate alternatives at different reading levels. (Metadata Technique)

  • Using the Dublin Core accessibility element to associate text content with text, graphical, or spoken supplements (future link)

  • Using the ISO AfA accessibility element to associate text content with text, graphical, or spoken supplements (future link)

  • Using the IMS accessibility element to associate text content with text, graphical, or spoken supplements (future link)

  • Making metadata viewable by humans (future link)

    • EXAMPLE: Providing, in metadata, URL(s) that point to a pre-primary-reading-level and a primary-reading-level text transcript of a new scientific discovery advanced-reading-level article.


The following are common mistakes that are considered failures of Success Criterion 3.1.5 by the WCAG Working Group.

(No failures currently documented)

Key Terms

lower secondary education level

the two or three year period of education that begins after completion of six years of school and ends nine years after the beginning of primary education

Note: This definition is based on [UNESCO].

supplemental content

additional content that illustrates or clarifies the primary content

Example 1: An audio version of a Web page.

Example 2: An illustration of a complex process.

Example 3: A paragraph describing the major outcomes and recommendations made in a research study.