WCAG Levels: A, AA, and AAA Explained

WCAG success criteria are assigned one of three conformance levels — A, AA, or AAA — based on how essential the requirement is and how broadly it can be applied. Understanding what each level means — and what it does not mean — helps organizations set realistic compliance goals and make informed decisions about accessibility investment.

Level A — The minimum baseline

Level A criteria address absolute barriers — situations where a user with a disability would find the content completely unusable without remediation. These are non-negotiable regardless of industry, budget, or organization size.

Key Level A requirements (examples)

Criterion	What it requires	Who it helps
1.1.1 Non-text Content	All images, icons, and non-text elements have meaningful alt text (or empty alt for decorative)	Blind users, screen reader users
1.3.1 Info and Relationships	Structure conveyed visually (headings, lists, tables) is also conveyed in markup	Screen reader users, braille display users
1.4.1 Use of Colour	Colour is not the only means of conveying information or indicating an action	Colour-blind users
2.1.1 Keyboard	All functionality is available via keyboard alone	Motor disability users, keyboard-only users
2.4.2 Page Titled	Every page has a descriptive title	All users, especially screen reader users navigating between tabs
3.1.1 Language of Page	The human language of the page is identified in the HTML	Screen readers (correct pronunciation), translation tools
4.1.2 Name, Role, Value	All UI components have accessible names and roles exposed to assistive technologies	Screen reader users, switch access users

Level AA — The legal standard

Level AA is the conformance level required by Canadian law (the AODA, the ACA framework via EN 301 549, and the Government of Canada standard). It addresses significant barriers that affect large groups of users while remaining achievable for most organizations with reasonable effort.

Key Level AA requirements (examples)

Criterion	What it requires	Who it helps
1.4.3 Contrast (Minimum)	Text has a contrast ratio of at least 4.5:1 (3:1 for large text)	Low vision users
1.4.4 Resize Text	Text can be resized up to 200% without loss of content or functionality	Low vision users
1.4.10 Reflow	Content reflows to a single column at 320px width without horizontal scrolling	Low vision users (zoom), mobile users
1.4.11 Non-text Contrast	UI components and graphical objects have 3:1 contrast ratio against adjacent colours	Low vision users
1.4.12 Text Spacing	No loss of content when letter/word/line spacing is adjusted	Dyslexia, cognitive disabilities
2.4.3 Focus Order	Keyboard focus order is logical and preserves meaning	Keyboard-only users
2.4.7 Focus Visible	Keyboard focus indicator is visible	Keyboard-only users
3.2.3 Consistent Navigation	Navigation repeated on multiple pages appears in the same order	Cognitive disabilities
3.3.1 Error Identification	Input errors are identified and described to the user in text	Cognitive disabilities, motor disabilities
3.3.2 Labels or Instructions	Labels or instructions are provided for user input	Cognitive disabilities

Contrast at Level AA

Designer

Level AA requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text (18pt or 14pt bold). Here are examples of common pairings:

Aa

Aa

Aa

Aa

Level AAA — Enhanced accessibility

Level AAA criteria address additional barriers for specific disability groups, often in situations where full conformance may not be achievable for all content types. The W3C itself notes that “it is not recommended that Level AAA conformance be required as a general policy for entire sites.”

However, many individual Level AAA criteria are achievable and highly beneficial. Organizations serving disability communities, government bodies, or healthcare should strongly consider AAA criteria even where not legally required.

Key Level AAA requirements (examples)

Criterion	What it requires	Who it helps
1.4.6 Contrast (Enhanced)	Text has a contrast ratio of at least 7:1 (4.5:1 for large text)	Low vision users (moderate impairment)
1.4.7 Low or No Background Audio	Background audio is quiet, can be turned off, or content has no background audio	Hard of hearing users, cognitive disabilities
2.1.3 Keyboard (No Exception)	All functionality is keyboard accessible — no exceptions for drag-and-drop or drawing interfaces	Motor disabilities
2.2.3 No Timing	No time limits except for real-time events	Cognitive disabilities, motor disabilities
2.3.2 Three Flashes	No content flashes more than 3 times per second	Photosensitive epilepsy
2.4.9 Link Purpose (Link Only)	Every link purpose is clear from the link text alone, without surrounding context	Screen reader users (list-of-links navigation)
3.1.3 Unusual Words	Definitions are provided for unusual words, jargon, or idioms	Cognitive disabilities, non-native speakers
3.1.5 Reading Level	Content is written at lower secondary education level, or a simplified version is available	Cognitive disabilities, literacy barriers
3.3.4 Error Prevention (Legal, Financial, Data)	Users can review, correct, and confirm submissions before finalizing	Cognitive disabilities, motor disabilities

Contrast at Level AAA

Designer

Level AAA requires a minimum ratio of 7:1 for normal text. This site targets AAA contrast throughout:

Aa

Aa

Aa

Choosing your target level

Leadership

Situation	Recommended target
Minimum legal compliance (Ontario AODA)	WCAG 2.1 Level AA
Minimum legal compliance (federal ACA)	WCAG 2.1 Level AA
Government of Canada digital services	WCAG 2.1 Level AA (targeting AAA where feasible)
Serving users with disabilities (disability orgs, assistive tech)	WCAG 2.1 Level AAA
Public sector (healthcare, education)	WCAG 2.1 Level AA, selected AAA criteria
High-risk services (financial, legal, emergency)	WCAG 2.1 Level AA + 3.3.4 Error Prevention (AAA)

What the levels do NOT mean

Does Level A mean 'basic' and AAA mean 'perfect'?

Not quite. Level A means “essential for any access at all.” Level AA means “accessible to most users.” Level AAA means “additional enhancements for specific groups.” A site can meet AAA and still have usability problems for real users — the levels measure conformance to a technical standard, not overall user experience quality.

Can automated tools determine my conformance level?

Automated tools can reliably check some criteria (colour contrast, image alt text presence, form labels) but cannot check many others (alt text quality, logical reading order, plain language). Automated checks cover roughly 30–40% of WCAG criteria. Manual review and testing with assistive technologies is required for a complete conformance assessment.

Does meeting WCAG 2.1 AA mean I automatically meet WCAG 2.0 AA?

Yes. WCAG 2.1 is backwards-compatible with WCAG 2.0. Every WCAG 2.0 criterion is included unchanged in WCAG 2.1. If you meet WCAG 2.1 Level AA, you meet WCAG 2.0 Level AA — satisfying the AODA requirement while also addressing the additional criteria added in 2.1.

What about WCAG 2.2 — does it change anything in Canada?

WCAG 2.2 (published October 2023) adds 9 new criteria and removes one (4.1.1 Parsing, now made obsolete by modern browser behaviour). Canadian law currently references WCAG 2.0 (AODA) or WCAG 2.1 via EN 301 549. WCAG 2.2 is not yet legally required in Canada, but it is the current published version and targeting it is recommended for new projects. See Canadian Baseline for details.

Related pages

• WCAG Overview — structure, versions, and how WCAG connects to Canadian law
• Canadian Baseline — the recommended Canadian standard
• Design Principles — implementing contrast and visual requirements
• Development Practices — implementing keyboard and semantic requirements