What Is WCAG? A Plain-English Guide to the Web Accessibility Guidelines Behind Readable Websites
WCAG is the standard behind most web accessibility laws and audits. Here's what it actually says about color contrast, text size, and spacing, in plain English.
If you’ve ever seen a website claim it’s “WCAG compliant” or read about a lawsuit over an inaccessible site, WCAG is the standard behind it. It’s not a law itself, but it’s the technical rulebook that most accessibility laws and audits point to. This guide explains what WCAG actually covers, in plain English, and which parts of it matter most if you’re someone who struggles to read text on the web comfortably.
What WCAG actually is
WCAG stands for Web Content Accessibility Guidelines. It’s published by the World Wide Web Consortium (W3C) through its Web Accessibility Initiative, and it’s the closest thing the web has to a shared definition of “accessible.” Governments and companies rarely write their own accessibility rules from scratch — they reference WCAG instead, which is why the same handful of success criteria show up again and again in accessibility policies, procurement requirements, and legal settlements around the world.
WCAG has gone through several versions (2.0, 2.1, and 2.2, with each new version adding criteria rather than replacing old ones), but the underlying structure has stayed the same since 2.0.
The four principles: POUR
Every WCAG rule falls under one of four principles, often abbreviated POUR:
- Perceivable — information has to be presented in ways people can actually perceive, such as sufficient color contrast, text alternatives for images, and content that doesn’t rely on color alone to convey meaning.
- Operable — interface components have to be usable, including full keyboard operability and enough time to read or interact with content.
- Understandable — text and interface behavior have to be predictable and readable, not just technically present.
- Robust — content has to work reliably with the different tools people use to access it, including screen readers and other assistive technology.
Most of the criteria that affect reading comfort specifically fall under Perceivable and Understandable.
The three conformance levels
WCAG success criteria are grouped into three levels of increasing strictness:
| Level | What it means |
|---|---|
| A | The minimum. Missing these creates serious barriers for some users. |
| AA | The level most laws, organizations, and audits actually require. |
| AAA | The strictest level, covering more specialized needs; the W3C itself notes it isn’t recommended as a general requirement for entire sites. |
When someone says a site is “WCAG compliant,” they almost always mean Level AA, not AAA. A handful of Level AAA criteria are still worth knowing even though they’re not typically mandatory, because they describe what genuinely comfortable reading looks like rather than the bare minimum.
The WCAG rules that matter most for reading
Most of WCAG covers things like forms, navigation, and video captions. A smaller set of criteria directly shape how comfortable text is to read:
- Color contrast (1.4.3, Level AA) — normal text needs a contrast ratio of at least 4.5:1 against its background; large text (roughly 18pt, or 14pt bold) needs at least 3:1. This is the same underlying problem covered in more practical detail in how to reduce eye strain when reading online.
- Resize text (1.4.4, Level AA) — text has to be resizable up to 200% using standard browser zoom without losing content or breaking layout.
- Reflow (1.4.10, Level AA) — at 400% zoom, content should reflow into a single readable column instead of forcing horizontal scrolling.
- Text spacing (1.4.12, Level AA) — a page shouldn’t break or clip content when a user increases line height to 1.5x the font size, paragraph spacing to 2x, letter spacing to 0.12x, and word spacing to 0.16x.
- Visual presentation (1.4.8, Level AAA) — a stricter, optional set of rules covering things many readers with dyslexia or low vision find genuinely helpful: user-selectable foreground and background colors, no fully justified text, line spacing of at least 1.5, and lines no wider than about 80 characters.
None of these guarantee a page is easy to read — a site can pass every one and still use a font or layout some readers find difficult. But together they describe a reasonable floor: text that’s legible, resizable, and adjustable enough for most people to use comfortably.
Why this matters even if you’ll never run an audit
You don’t need to be a developer or an auditor for WCAG to be useful to you. It’s a concrete description of what “readable” means at a technical level, which makes it a good checklist for diagnosing why a specific page is hard for you to read: is the text too low-contrast? Does the site break when you zoom in? Does it ignore your browser’s font size setting? Naming the specific problem, rather than just “this is hard to read,” makes it much easier to find or ask for a fix.
What to do when a site falls short
Plenty of sites don’t meet even Level A, and you can’t file a complaint every time. When a page itself won’t cooperate, the more practical option is adjusting how you read it, rather than waiting for the site to change:
- Use your browser’s built-in zoom and text size settings first — most modern browsers handle reflow reasonably well even on sites that don’t explicitly support it.
- Apply a reading tool that overrides a page’s font, spacing, and color scheme directly, instead of relying on the site to offer those options.
- Pair visual adjustments with text-to-speech when contrast or layout issues make a page difficult to read visually at all.
ReadEase applies several of the same fixes WCAG describes — contrast, font, line height, letter spacing — directly to any page you’re reading, regardless of whether the site itself was built with those guidelines in mind.
Frequently asked questions
Is WCAG a law?
No. WCAG is a technical standard published by the W3C. Laws and regulations in different countries (such as the ADA in the U.S. or the EN 301 549 standard in the EU) often require accessibility and point to WCAG as the technical benchmark, but WCAG itself isn’t legislation.
What WCAG level should a website aim for?
Level AA is the practical target used by most accessibility laws, audits, and organizations. Level AAA contains some genuinely useful criteria for reading comfort, but the W3C doesn’t recommend it as a blanket requirement for entire websites.
Does passing WCAG mean a site is easy to read?
Not automatically. WCAG sets a floor for legibility, contrast, and adjustability, but a page can technically pass every applicable criterion and still use a font, layout, or line length that some readers find difficult. It’s a useful baseline, not a guarantee of comfortable reading.
Can I fix WCAG-related problems myself as a reader?
For many of the issues WCAG covers, yes. Low contrast, small text, tight line spacing, and fixed layouts can often be overridden using your browser’s settings or a reading extension, even if the site itself never fixes the underlying problem.