3.1.5 Reading Level

Level: AAA | Principle: Understandable | Since: WCAG 2.0 | Automation: Manual

What This Means

When text content requires a reading ability more advanced than the lower secondary education level (approximately grade 7-9, ages 12-15), supplemental content must be provided. The supplemental content can be a simplified version, illustrations, diagrams, or a summary written at a lower reading level.

This does not mean all content must be written at a grade 7 level. Complex topics like medical research, legal documents, and technical specifications may inherently require advanced reading skills. The requirement is that a supplemental version or aid must be available to help users who cannot read at that level.

Reading level can be measured with formulas like the Flesch-Kincaid Grade Level, Gunning Fog Index, or SMOG Index. Many free tools calculate these automatically from your text.

Who This Affects

Users with cognitive or learning disabilities — including dyslexia, intellectual disabilities, and language processing disorders
Non-native speakers — complex sentence structures and advanced vocabulary are barriers
Users with low literacy — approximately 21% of US adults read at or below a 5th grade level
Older adults with cognitive decline — complex text becomes harder to process

Common Pitfalls

1. Complex legal language with no plain-English summary

<!-- Bad: dense legal text with no alternative -->
<div class="terms">
  <p>Notwithstanding the foregoing provisions, the indemnifying party shall hold
  harmless the indemnified party from any and all claims, damages, losses, costs,
  and expenses (including reasonable attorneys' fees) arising from or related to
  any breach of the representations and warranties set forth herein.</p>
</div>

<!-- Good: plain-language summary provided alongside -->
<div class="terms">
  <details>
    <summary>Plain language summary</summary>
    <p>If we break our promises in this agreement, we will cover any costs or
    damages you face as a result, including your legal fees.</p>
  </details>
  <p>Notwithstanding the foregoing provisions, the indemnifying party shall hold
  harmless the indemnified party from any and all claims...</p>
</div>

2. Technical documentation with no beginner guide

<!-- Good: provide a simplified version alongside technical docs -->
<nav aria-label="Documentation versions">
  <a href="/docs/quickstart">Beginner guide (simplified)</a>
  <a href="/docs/reference" aria-current="page">Technical reference</a>
</nav>

How to Test

Copy a representative block of text from the page and paste it into a readability tool (Hemingway App at hemingwayapp.com, or readable.com).
Check the Flesch-Kincaid Grade Level. If it is above grade 9, supplemental content is needed.
Look for a simplified summary, beginner-friendly version, illustrations, or diagrams near the complex content.
Verify the supplemental content is easy to find (clearly linked or displayed alongside the complex text).
Pass: Content at or below a grade 9 reading level, or complex content has a clearly linked simplified version, summary, or visual aid.
Fail: Content exceeds grade 9 reading level with no supplemental simplified version, summary, or illustrations available.

How to Fix

Run readability analysis on all content and identify pages above a grade 9 reading level
Write plain-language summaries for complex content (use short sentences, common words, active voice)
Add illustrations, diagrams, or infographics to explain complex concepts visually
Provide a "simple language" toggle or a separate simplified version of the page
Use the <details> and <summary> elements to offer expandable plain-language explanations