WCAG and dyslexia - what web accessibility compliance covers and what it misses
A website can carry the "WCAG 2.1 Level AA compliant" badge and still be exhausting for a dyslexic reader to use. Justified 14-pixel serif text with tight line height, grey on a slightly lighter grey background, 100-character line lengths - all of that can pass an automated accessibility audit. The gap between "compliant" and "readable for dyslexic people" is real, and it matters whether you're a reader wondering why a supposedly accessible site still hurts to read, or a developer who wants to do better than the legal minimum.
This article goes through the relevant WCAG criteria one by one, explains what they do and don't cover for dyslexic readers, and points to practical steps on both sides - for people using the web and for people building it.
What WCAG is and how the levels work
The Web Content Accessibility Guidelines (WCAG) are published by the W3C and sit behind most accessibility law. The UK's Public Sector Bodies Accessibility Regulations, the EU's Web Accessibility Directive, and the US Section 508 all point at WCAG as the technical standard. Most require Level AA - a middle tier that sits between the basic Level A requirements and the demanding Level AAA.
Level AA is achievable with reasonable effort for most web projects. Level AAA includes criteria that are either technically difficult to implement at scale or that create genuine trade-offs with other design requirements. AAA is aspirational for most sites and legally required for almost none.
For dyslexic readers, this distinction matters a lot, because the most relevant criteria for dyslexia are mostly AAA.
What WCAG AA actually requires for text
Several AA criteria touch on text presentation. Here is what each one covers - and crucially, what it leaves out.
1.4.3 Contrast (Minimum) - Level AA
Normal body text must have a contrast ratio of at least 4.5:1 against its background. Large text (18pt regular or 14pt bold) gets a lower threshold of 3:1. This is the criterion most people associate with accessibility, and it genuinely helps dyslexic readers by preventing the low-contrast grey-on-white text that causes visual fatigue.
What it does not cover: the criterion is purely about the ratio, not about what the colours actually are. Dark grey text on a slightly less dark grey background can pass 4.5:1. Bright white text on a saturated colour background can pass too. Contrast ratio is a necessary condition for readability, not a sufficient one. For more on this, see our post on background colours for dyslexia and the closely related piece on contrast sensitivity in dyslexic readers.
1.4.4 Resize Text - Level AA
Text must remain readable and functional when resized up to 200 percent without assistive technology. In practice this means the site cannot break its layout when a user increases browser zoom. This is a meaningful win for dyslexic readers who benefit from larger text - but the criterion only requires that the site can be zoomed, not that it provides a font-size control of its own. See our piece on best font size for dyslexic adults for the practical numbers.
1.4.10 Reflow - Level AA
Content must be presentable without horizontal scrolling at a viewport width equivalent to 320 CSS pixels. This matters for mobile users and for people who zoom heavily on desktop. It does not address font choice, spacing, or alignment.
1.4.12 Text Spacing - Level AA
This is the criterion most directly useful for dyslexic readers, and it is often misunderstood. Criterion 1.4.12 does not require sites to use generous spacing. What it requires is that if a user overrides text spacing via their own CSS - setting line height to at least 1.5 times the font size, letter spacing to at least 0.12em, word spacing to at least 0.16em, and spacing after paragraphs to at least 2em - the site must not break. Content must remain readable and no functionality must be lost.
This is actually a useful protection. It means that a tool like LexiFont or a custom stylesheet can safely apply dyslexia-friendly spacing on most AA-compliant sites without the layout falling apart. See our post on line spacing and letter spacing for dyslexia for what the ideal numbers look like in practice.
The practical implication of 1.4.12: if a site claims AA compliance and LexiFont's spacing overrides break the layout, the site probably fails 1.4.12. This is a bug in the site, not a limitation of the extension.
What WCAG AA does not require for text
The following are things that matter significantly for dyslexic readers but that WCAG AA does not mandate:
Font family. WCAG has no requirement to use a dyslexia-friendly typeface, or any particular typeface at all. A site can use Times New Roman at AA and be compliant. Our posts on serif vs sans-serif for dyslexic readers and best fonts for dyslexia in 2026 cover the evidence on font choice - evidence that WCAG does not yet incorporate.
Justified text. WCAG AA does not prohibit justified text alignment. Justified text creates rivers of white space between words, and the irregular spacing disrupts the visual rhythm that dyslexic readers rely on to track across a line. It is one of the more reliably harmful things a site can do to dyslexic readers, and it is not covered. See our full piece on justified vs left-aligned text for dyslexia.
Maximum line length. Very long line lengths (above roughly 70 characters) force the eye to make a long return sweep after each line, which causes dyslexic readers to lose their place more often. WCAG AA does not set a maximum. See our post on line length and dyslexia for the practical guidance.
Minimum line height beyond what 1.4.12 protects. 1.4.12 protects against sites breaking when spacing is overridden, but a site that uses 1.2 line height by default is AA-compliant. Most researchers and practitioners suggest 1.5 as a baseline for dyslexic readers.
Background colour choices. A site can use pure white backgrounds (which can cause glare and visual stress for some dyslexic readers) and remain AA-compliant, as long as the text passes the contrast ratio. Some readers find cream or light grey backgrounds significantly more comfortable - but this is personal, and WCAG does not address it at the AA level.
To see just how wide the gap can be, consider this comparison:
This paragraph uses 14-pixel Times New Roman, justified alignment, 1.3 line height, and a 100-character line width. It passes a contrast check at 4.5:1. An automated audit returns zero issues. A dyslexic reader may find it difficult to decode letter by letter, lose their place on the long return sweep, and experience the uneven spacing between words as visual interference.
This paragraph uses Atkinson Hyperlegible at 16 pixels, left-aligned, with 1.65 line height and a comfortable line width. It also passes at 4.5:1 contrast. But it was designed from the start with low-vision and dyslexic readers in mind. The letter shapes are distinct, the spacing is consistent, and the return sweep is short enough to land reliably on the next line.
The AAA criterion that actually targets dyslexia
WCAG includes one criterion that maps almost exactly onto dyslexia research: 1.4.8, Visual Presentation, at Level AAA. It requires all of the following for blocks of text:
The foreground and background colours can be selected by the user. Width is no more than 80 characters. Text is not fully justified. Line spacing is at least 1.5 times the font size within paragraphs. Spacing between paragraphs is at least 1.5 times the line spacing. Text can be resized up to 200 percent without assistive technology and without requiring horizontal scrolling.
If you read the dyslexia-friendly web design checklist on this site, you will notice the WCAG 1.4.8 requirements and the dyslexia research recommendations are nearly identical. That is not a coincidence - the criterion was written with low-vision and reading-difficulty users in mind. The problem is that it sits at AAA, which means almost no site is required to implement it.
What WCAG 2.2 and future versions may bring
WCAG 2.2, published in October 2023, added several new criteria - Focus Appearance, Target Size, Accessible Authentication, and others. None of them directly address dyslexia or text rendering. The additions are mostly relevant to motor impairments and cognitive load in form interactions.
WCAG 3.0, which the W3C is developing under the working title "Silver," takes a different approach to scoring. Rather than a binary pass/fail against criteria, it uses an outcomes-based rating across functional needs categories. Dyslexia and reading difficulties are among the user groups explicitly named in the draft. Whether the eventual standard produces meaningfully stronger protections for dyslexic readers than WCAG 2.x remains to be seen - the draft has been in development for several years and the timeline to publication is uncertain.
For now, WCAG AA is the floor, not the ceiling.
What this means if you are a reader with dyslexia
Compliance badges on websites do not mean the site was designed with dyslexic readers in mind. They mean the site passed a threshold that was set primarily for blind and low-vision users and people with motor impairments.
The practical upshot:
First, use your browser's zoom. Every AA-compliant site must work at 200 percent zoom, so this is a reliable lever. The guide to browser zoom and text scaling for dyslexia explains how to set a persistent default.
Second, because 1.4.12 requires AA sites to tolerate spacing overrides, a font-override tool like LexiFont can usually apply your preferred font and spacing without breaking the layout. If a site does break, that is the site's bug, not a limitation of the tool.
Third, reader mode in most browsers (Firefox, Safari, Edge) strips out the site's CSS entirely and replaces it with the browser's own clean layout. This sidesteps compliance questions altogether and gives you a predictable reading environment. See our comparison of reader mode vs reading extensions for dyslexia for when each approach works better.
What this means if you are building a website
AA compliance is worth having - it means your site does not actively punish users who need to zoom, does not render text invisible against its background, and does not break when someone applies a custom stylesheet. That is a genuine baseline.
But if you want your site to be comfortable for dyslexic readers, there are low-effort additions that go beyond AA without approaching AAA complexity. Left-align all body text. Limit your content width to around 65-70 characters per line. Use a line height of 1.5 or above. Choose a font with well-differentiated letterforms - Atkinson Hyperlegible, Lexend, and even well-tuned system fonts like system-ui are all better choices for readability than default serif stacks. These changes take about 20 minutes to implement and require no specialist knowledge.
If you want to reach AAA for 1.4.8, the additional step is giving users the ability to choose their own foreground and background colours - which in practice means either a site-level colour theme switcher or ensuring your site respects the prefers-color-scheme media query and does not override user stylesheets with !important declarations.
Automated auditing tools (axe, WAVE, Lighthouse) catch most AA contrast failures and some structural issues, but they cannot catch justified text, long line lengths, or poor font choices. A five-minute manual review by someone who reads your content regularly is worth more than a green audit score for catching the dyslexia-relevant issues.
For a complete checklist, see our dyslexia-friendly web design checklist, which goes through each of the AA and AAA criteria alongside the research-backed recommendations that sit outside the standard entirely.
If you are a reader, not a developer: LexiFont applies dyslexia-friendly fonts and spacing to any website in Chrome, covering the gap between what AA requires and what actually helps. The free tier includes OpenDyslexic and core spacing adjustments. LexiFont Pro adds Lexend, Atkinson Hyperlegible, and per-site memory so your settings follow you automatically.
The structural problem with standards and dyslexia
WCAG was largely designed around assistive technology users - primarily screen reader users and people navigating by keyboard. The criteria map well onto those needs. Dyslexia presents a different challenge: dyslexic readers usually have enough vision to read text without assistive technology, but the typographic choices made by default by most websites create unnecessary friction. That friction is invisible to automated tools, invisible to sighted reviewers who don't experience it themselves, and invisible to the WCAG audit.
This is not a criticism of WCAG - it is a general-purpose standard that has to work across a huge range of disabilities and technologies. But it means that "accessible" and "readable for dyslexic people" are not synonyms, and treating the AA badge as evidence of the latter is a mistake.
The gap is also why browser-level tools remain important even on well-designed sites. A font that works well for most readers may still be difficult for a specific individual, and the right tool in that case is one that lets the reader set their own preferences - which is exactly what the 1.4.8 AAA criterion was trying to guarantee at the site level, without full success.
Further reading
- Dyslexia-friendly web design checklist - practical criteria beyond WCAG
- Justified vs left-aligned text for dyslexia - what the research shows
- Line spacing and letter spacing for dyslexia - the numbers that matter
- Serif vs sans-serif fonts for dyslexic readers - what the research says
- Reader mode vs reading extensions - which is better for dyslexia?