WCAG Levels A, AA, and AAA: What They Mean and What to Aim For

The short version

WCAG, short for the Web Content Accessibility Guidelines, comes from the W3C, the same body that maintains core web standards. The current version is WCAG 2.2. Every success criterion in it is assigned a conformance level: A, AA, or AAA.

The levels are cumulative. Meeting Level AA means you've also met every Level A requirement. Meeting AAA means you've met A and AA too. Nothing gets easier as you move up. Each level adds more criteria on top of the last, aimed at a wider range of people and situations.

Level A

Level A is the floor. It covers the most basic barriers, the ones that make content unusable, not just inconvenient. A site failing Level A likely has real problems: images with no alt text, content that can't be reached by keyboard, color used as the only way to convey information.

Take Success Criterion 1.4.1, Use of Color. If a page distinguishes links from body text using color alone (blue text, no underline, same weight as everything else), it fails Level A, because a colorblind visitor has no way to tell a link from a sentence.

Level A is a starting point, not a destination. Plenty of Level A sites are still hard to use.

Level AA

Level AA is the working standard. It adds requirements that matter for a much larger group of visitors, without asking for extraordinary effort. This is the tier most organizations should actually be building for, and it's the one referenced almost everywhere accessibility comes up in a legal or grant context.

The clearest example is color contrast. Success Criterion 1.4.3 sets a minimum contrast ratio of 4.5:1 between text and its background. Level A only says "don't use color alone to convey meaning." Level AA says the color you do use has to be readable. A pale gray paragraph on a white background can pass Level A and still fail Level AA.

AA also covers things like captions for live video, audio descriptions for prerecorded video, and consistent, predictable navigation. None of it is exotic. Most of it is design discipline applied early instead of patched in later.

Level AAA

AAA is the highest tier, and it's demanding. Its own authors don't expect most sites to fully reach it. The W3C's own conformance documentation says Level AAA conformance is not recommended as a general policy for entire sites, because it isn't possible to satisfy every AAA success criterion for some kinds of content, no matter how the site is built.

Where Level AA requires 4.5:1 contrast, the AAA version of that same criterion (1.4.6, Contrast Enhanced) raises the bar to 7:1, which helps people with significantly lower vision read text without relying on assistive tools. Another AAA criterion asks for sign language interpretation of prerecorded audio content. That's valuable, but out of reach for most small organizations maintaining their own site.

AAA is worth knowing about, and worth borrowing from selectively. It's not a realistic target to chase wholesale.

What the law actually says

This is where most of the confusion sits, so let's be precise about it. WCAG itself is a set of guidelines, not a law. Nothing about WCAG requires anyone to do anything on its own. It becomes a legal question through how other laws and courts point to it.

In April 2024, the Department of Justice finalized a rule under Title II of the ADA that names WCAG 2.1 Level AA as the specific technical standard for state and local government websites and mobile apps: public schools, libraries, transit agencies, courts, and similar public entities. That rule comes with real deadlines. Governments serving 50,000 or more people must comply by April 26, 2027. Smaller governments and special districts have until April 26, 2028.

That rule, though, only covers government entities. Private businesses and private nonprofits fall under a different part of the ADA, Title III, and there's currently no DOJ regulation spelling out a technical standard for them. In practice, that gap hasn't stopped lawsuits. Courts and settlements involving private companies have consistently pointed to WCAG 2.1 AA as the practical benchmark for what counts as accessible, even without a formal rule requiring it. That's the real reason AA has become the de facto standard everyone cites, government website or not.

So what should you aim for

For nearly every small business, nonprofit, or church site: build to WCAG 2.2 Level AA. It's the current version, it's backward-compatible with the 2.1 AA standard referenced in the ADA rule and most legal precedent, and it's realistic to build and maintain without a dedicated accessibility team.

From there, treat AAA as a source of good ideas, not a checklist. If a higher contrast ratio is easy to apply site-wide, use it. If sign language interpretation isn't realistic for your video content, don't let that block you from shipping the AA version. The goal is a site your visitors can actually use, whoever they are and whatever they're using to browse it.