WCAG 2.1 AA Checklist
WCAG 2.1 Level AA has 50 success criteria across four principles (Perceivable, Operable, Understandable, Robust). This plain-English checklist explains each criterion with real examples — no jargon.
The official WCAG 2.1 specification is written for accessibility researchers — dense, technical, hard to read.
This version translates every WCAG 2.1 AA criterion into plain English, with practical examples of what passes and what fails.
Principle 1: Perceivable
Users must be able to perceive the content. This includes alternatives for non-text content, captions for media, and enough color contrast.
- Images have descriptive alt text. Every image that carries meaning has descriptive alt text. Decorative images have alt="" (empty). ❌ Fails: <img src="dog.jpg"> ✅ Passes: <img src="dog.jpg" alt="Golden retriever fetching a ball">
- Videos have captions. Pre-recorded videos have synchronized captions; live streams have real-time captions.
- Text has 4.5:1 contrast with background. Light gray text on white fails. Dark gray on white usually passes. Use webaim.org/resources/contrastchecker/ to verify.
- Text resizes to 200% without breaking. Users can zoom to 200% without horizontal scrolling or cut-off text.
- Color alone doesn't convey meaning. A red "required" label needs more than just color — add an asterisk, the word "required", or similar.
- Content reflows to 320px wide. Mobile layout works without horizontal scrolling. Critical for mobile users with zoomed screens.
- UI components have 3:1 contrast. Button borders, form field outlines, icon buttons meet 3:1 ratio with their surroundings.
- Text spacing can be adjusted. When users override line-height, letter-spacing, or word-spacing via CSS overrides, content doesn't get cut off.
- Hover/focus content is manageable. Tooltips and popovers can be dismissed, are persistent (don't flicker away), and can be hovered by screen readers.
Principle 2: Operable
Users must be able to operate the interface. This means keyboard accessibility, enough time to interact, no seizure triggers, and clear navigation.
- Everything works with keyboard only. Press Tab through your site. Can you reach and activate every button, link, and form? No mouse required.
- No keyboard traps. You can always Tab/Shift+Tab out of every component. Modals have a close shortcut (usually Escape).
- Time limits can be adjusted. Session timeouts warn users and allow extensions. Auto-refreshing content has a pause control.
- Moving content can be paused. Carousels, animations, and auto-playing video have pause/stop controls.
- Nothing flashes > 3 times/second. Flashing content is a seizure trigger. Avoid or provide warning.
- Skip-to-main-content link exists. First focusable element is a "Skip to main content" link that bypasses navigation.
- Page has a descriptive title. <title> tag describes the page purpose. "Home" is too generic. "Home — OnlyEnable ADA Compliance" is better.
- Tab order is logical. Tab moves through elements in a sensible order — typically top-to-bottom, left-to-right, matching visual layout.
- Links have descriptive text. "Click here" is vague. "Download our accessibility checklist (PDF)" is clear.
- Multiple ways to find pages. Navigation menu + search + sitemap. Don't force single-path navigation.
- Headings and labels are clear. H1–H6 describe section topics. Form labels describe the expected input.
- Focus is visibly indicated. When you Tab to a button/link, a visible outline or highlight shows where you are.
Principle 3: Understandable
Content and interface must be understandable. This means predictable behavior, clear language, and helpful error messages.
- Page language is declared. <html lang="en"> tells screen readers which language to use for pronunciation.
- Focusing doesn't change context unexpectedly. Clicking a tab shouldn't redirect you. Focusing a dropdown shouldn't submit the form.
- Typing doesn't change context unexpectedly. A form field shouldn't submit the form when you type in it.
- Navigation is consistent across pages. Menu is in the same place, components have the same names on every page.
- Errors are identified in text. "Email must contain @" is better than just a red border. Users with color blindness can't see color-only errors.
- Form fields have labels. Every input has a <label> or aria-label. Placeholder text alone doesn't count — it disappears when you type.
- Error suggestions are provided. "Your password must be at least 8 characters" is helpful. "Invalid password" is not.
- Financial/legal data can be reviewed. E-commerce orders, legal form submissions should let users confirm before final submission.
Principle 4: Robust
Content must be robust enough to work with assistive technology — screen readers, voice control, magnifiers — now and in the future.
- Components have programmatic name, role, and value. A custom button needs role="button" and an accessible name. Screen readers need to know what elements are.
- Status messages reach assistive tech. When a form submits successfully, screen readers announce it via aria-live regions.
Principle 4 is short but critical. This is where overlays can't help — if your custom components don't have proper ARIA, no widget can fix that.
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Frequently asked questions
How long does a WCAG 2.1 AA audit take?+
For a 5-page site: 3-5 days. Medium site (50 pages): 2-3 weeks. Large site: a month or more.
Can I check WCAG compliance myself?+
Partially. You can run Lighthouse, WAVE, and axe DevTools yourself. These catch ~30% of issues. For the full picture, you need a specialist.
Does meeting WCAG 2.1 AA mean I'm ADA compliant?+
It substantially reduces your risk. US courts reference WCAG 2.1 AA as the ADA benchmark, so meeting it gives you strong documented defense — though no vendor can "guarantee" compliance.
What's the difference between WCAG A, AA, and AAA?+
A is minimum, AA is industry standard (what courts reference), AAA is aspirational for specialized contexts. Aim for AA.
Key takeaways
- WCAG 2.1 AA has 50 criteria across 4 principles
- Most failures happen in Perceivable (images, contrast) and Operable (keyboard) principles
- Automated tools catch ~30%; the other 70% need human testing
- This checklist is a starting point — use a specialist for a complete audit