WCAG Conformance Levels

What Are WCAG Conformance Levels?

A WCAG conformance level defines how fully a website or web application meets the Web Content Accessibility Guidelines (WCAG). These levels categorize accessibility success criteria into three tiers: A, AA, and AAA. Each level builds on the previous one, with increasing requirements for accessibility.

The Three Levels of Conformance

WCAG defines three progressive levels of conformance.

Level A (Minimum Requirements)

Level A addresses the most basic accessibility issues. Sites must ensure assistive technologies can access key content and functionality. Requirements include text alternatives for images, keyboard accessibility, and avoiding content that may trigger seizures.

Level AA (Industry Standard)

Level AA includes all Level A requirements plus additional criteria that improve usability and access. It sets standards for color contrast, responsive design, clear navigation, audio alternatives, and more. This is the level most commonly referenced by laws like the ADA, Section 508 (U.S.), and AODA (Canada).

Level AAA (Enhanced Accessibility)

The most advanced level, AAA, includes all criteria from Levels A and AA and introduces stricter requirements. This can include sign language for videos, full removal of time limits, and extended audio descriptions. AAA conformance is not always practical for all content types and is generally not required by regulation.

WCAG Versions and Compatibility

WCAG exists in multiple versions: 2.0, 2.1, and 2.2. While newer versions introduce additional success criteria, the three conformance levels apply consistently across all versions. Organizations bound by specific laws may be required to meet a particular version, such as WCAG 2.0 or 2.1.

Legal Relevance of WCAG Conformance

WCAG conformance is referenced in multiple legal frameworks around the world.

ADA (United States)

Though the ADA does not codify WCAG as law, U.S. courts and DOJ guidance commonly reference WCAG 2.0 or 2.1 Level AA as the recommended standard for web accessibility.

Section 508 (United States)

Section 508 mandates that federal agencies and those receiving federal funding make their web content accessible. The required standard is WCAG 2.0 Level AA.

AODA (Canada)

The Accessibility for Ontarians with Disabilities Act mandates WCAG 2.0 Level AA for public web content posted after 2012, with limited exceptions.

Choosing the Right Conformance Level

Level AA is generally considered the practical and legal standard. It balances technical feasibility with functional accessibility for users. Striving for AAA may be valuable for organizations committed to higher inclusion, but is rarely mandated.