WCAG 3.1.5 Reading Level: Write Content Everyone Can Understand

What This Criterion Requires

WCAG 3.1.5 requires that when text requires a reading ability more advanced than the lower secondary education level (approximately 7th to 9th grade, ages 12 to 15) after removal of proper names and titles, a supplemental version is provided that does not require such advanced reading ability. This criterion addresses the reality that a significant portion of the population reads below the average level. According to the National Center for Education Statistics, over half of U.S. adults read below a 6th-grade level. People with cognitive disabilities, learning disabilities such as dyslexia, and those for whom the language is not their first language are disproportionately affected by complex text. Meeting this criterion does not mean all content must be simplified, as some technical, legal, or scientific content inherently requires advanced vocabulary. Instead, it requires that supplemental content is available: summaries in plain language, visual explanations, glossaries, or simplified versions of key information. Tools like the Flesch-Kincaid readability test, Hemingway Editor, and the SMOG Index can help measure reading level. Best practices include using short sentences, common words, active voice, clear headings, and supplementary visuals like diagrams or infographics to support textual content.

Why It Matters

Reading level is one of the most overlooked accessibility barriers on the web. While many organizations focus on visual and motor accessibility, content comprehension affects a larger population. The World Literacy Foundation estimates that 773 million adults worldwide are functionally illiterate, and many more read at basic levels. In the United States alone, 54% of adults read below a 6th-grade level, and 130 million adults are considered low-literate. For people with cognitive disabilities such as intellectual disabilities, traumatic brain injuries, or age-related cognitive decline, complex text creates an impenetrable barrier to information. People with learning disabilities like dyslexia may be highly intelligent but struggle with dense, jargon-heavy text. Non-native speakers of a language may have strong conversational skills but find formal written content incomprehensible. Even within technical fields, unnecessary complexity reduces comprehension for everyone. Government services, healthcare information, legal documents, and financial disclosures are areas where inaccessible reading levels have the most severe consequences, as people cannot exercise their rights, make informed health decisions, or understand binding agreements. Plain language is not 'dumbing down' content; it is effective communication that respects the reader's time and cognitive resources.

Common Failures and How to Fix Them

<h1>Terms of Service</h1>
<p>The indemnification obligations herein shall
survive the termination of this Agreement and
shall extend to all claims arising from or
related to your utilization of the Services,
including but not limited to claims of
negligence, breach of warranty, and
misappropriation of intellectual property...</p>

<h1>Terms of Service</h1>
<div class="plain-language-summary" role="region"
  aria-label="Plain language summary">
  <h2>Summary in Plain Language</h2>
  <p>If something goes wrong because of how you
  used our service, you agree to cover the costs.
  This applies even after you stop using our
  service.</p>
  <p><a href="#full-terms">Read the full legal
  terms below</a></p>
</div>
<div id="full-terms">
  <h2>Full Legal Terms</h2>
  <p>The indemnification obligations herein...</p>
</div>

<h2>About Hypertension</h2>
<p>Essential hypertension is characterized by
chronically elevated systemic arterial pressure
resulting from increased peripheral vascular
resistance, frequently associated with
endothelial dysfunction and arterial
remodeling.</p>

<h2>About High Blood Pressure</h2>
<p>High blood pressure (also called hypertension)
means the force of blood pushing against your
artery walls is too high. Over time, this can
damage your blood vessels and heart.</p>
<details>
  <summary>Medical terminology</summary>
  <p>Essential hypertension is characterized by
  chronically elevated systemic arterial pressure
  resulting from increased peripheral vascular
  resistance.</p>
</details>

<p>Applicants who are desirous of obtaining
benefits pursuant to Section 402(a) must submit
a completed Form SSA-561-U2, which shall be
adjudicated within 60 days of receipt by the
appropriate adjudicative body.</p>

<p>To apply for benefits:</p>
<ol>
  <li>Fill out <a href="/forms/ssa-561">Form
    SSA-561</a></li>
  <li>Submit it online or by mail</li>
  <li>We will review your application and respond
    within 60 days</li>
</ol>
<p>Need help? Call us at 1-800-XXX-XXXX or
  <a href="/help">visit your local office</a>.</p>

How to Test

1. Copy the main text content (excluding proper names and titles) into a readability checker such as Hemingway Editor (hemingwayapp.com) or a Flesch-Kincaid calculator.
2. Check whether the content scores at or below a 9th-grade reading level (Flesch-Kincaid Grade Level of 9 or lower).
3. For content that exceeds this level, verify that a plain-language summary, simplified version, or supplementary visual explanation is provided.
4. Review key pages such as terms of service, privacy policies, help documentation, and instructional content for readability, as these are most critical for user comprehension.

CMS-Specific Guidance

This criterion commonly causes issues on these platforms:

• Wordpress Accessibility Checklist
• Shopify Accessibility Checklist
• Squarespace Accessibility Checklist
• Wix Accessibility Checklist

Further Reading

• Accessible Content Writing Guide
• Wcag Explained Plain English
• Accessibility Statement Guide

Related WCAG Criteria

• WCAG 3.1.3
• WCAG 3.1.1
• WCAG 3.1.2