WCAG 2.0 is the second major release of the W3C accessibility guidelines, finalised in December 2008, with 61 success criteria, of which 38 make up level AA. It is still valid, it is the ISO/IEC 40500 standard, and US Section 508 and Ontario's AODA still point to it.
It is also the foundation of everything that came later. Every 2.0 criterion carried over into 2.1 and 2.2 except parsing, so learning 2.0 well is learning the core of modern accessibility.
Quick facts
Published
W3C Recommendation, December 2008.
Success criteria
61 in total: 25 at A, 13 at AA, 23 at AAA.
Level AA means
38 criteria (all 25 A plus 13 AA).
Structure
4 principles and 12 guidelines.
Still required by
Section 508 in the US and AODA in Ontario, among others.
Also known as
ISO/IEC 40500.
What WCAG 2.0 is
The 2.0 release replaced the checkpoint style of WCAG 1.0 with outcome based, testable success criteria that do not depend on any single technology. That change is why a document from December 2008 can still be applied to modern JavaScript apps. You can read the original text at w3.org/TR/WCAG20.
Its four principles, often called POUR, are the same ones used today and are explained on our WCAG principles page. Under them sit 12 guidelines, listed below.
The twelve guidelines
WCAG 2.1 later added a thirteenth guideline, 2.5 Input Modalities, but the original twelve remain the backbone.
| Guideline | Principle | What it covers |
|---|---|---|
| 1.1 Text Alternatives | Perceivable | Alt text and other text versions of non-text content |
| 1.2 Time-based Media | Perceivable | Text and sound alternatives for video and audio |
| 1.3 Adaptable | Perceivable | Structure and reading order that survive a change of presentation |
| 1.4 Distinguishable | Perceivable | Contrast, resizing, audio control, color use |
| 2.1 Keyboard Accessible | Operable | Full keyboard use with no traps |
| 2.2 Enough Time | Operable | Adjustable time limits and controls for moving content |
| 2.3 Seizures | Operable | Limits on flashing content |
| 2.4 Navigable | Operable | Titles, skip links, focus order, link purpose, headings |
| 3.1 Readable | Understandable | Page language and language changes |
| 3.2 Predictable | Understandable | No surprise changes, consistent navigation |
| 3.3 Input Assistance | Understandable | Labels, error messages and error prevention |
| 4.1 Compatible | Robust | Valid markup and correct name, role and value |
WCAG 2.0 level AA criteria
WCAG 2.0 level AA asks for 38 criteria: the 25 at level A and these 13 at AA.
| Criterion | In plain words |
|---|---|
| 1.2.4 | Live video with sound gets real time captions |
| 1.2.5 | Recorded video explains key visual details in sound |
| 1.4.3 | 4.5:1 for body copy, 3:1 for big text |
| 1.4.4 | Doubling text size breaks nothing |
| 1.4.5 | Words are typed, not baked into pictures |
| 2.4.5 | Search, a sitemap or links offer more than one route to a page |
| 2.4.6 | Section titles and field names describe their purpose |
| 2.4.7 | Keyboard users can see where they are |
| 3.1.2 | Passages in another language are marked up |
| 3.2.3 | Shared menus keep their order across pages |
| 3.2.4 | Things that do the same job are named the same way |
| 3.3.3 | When the site knows the fix, it tells the user |
| 3.3.4 | Important submissions can be checked, confirmed or reversed |
Where 2.0 compliance is still required
WCAG 2.0 compliance at AA is a legal baseline in several places. This is general background; check the official text for anything binding.
| Rule | Where | What it uses |
|---|---|---|
| Revised Section 508 Standards | Federal bodies in the US, plus their purchases | WCAG 2.0 AA for web content, documents and software |
| AODA | Ontario, Canada | WCAG 2.0 AA for many organisations |
| ISO/IEC 40500 | International | The same text as WCAG 2.0, as an ISO standard |
| Older contracts and policies | Anywhere | Often name 2.0 AA because it was current when written |
Details for federal work are on section508.gov. For other countries see accessibility laws.
What version 2.0 does not cover
A site that is WCAG 2.0 AA compliant can still fail a lot of real users, especially on phones. These are the gaps that 2.1 and 2.2 filled.
| Problem 2.0 does not address | Criterion that fixed it | Added in |
|---|---|---|
| Screen stuck in one rotation | 1.3.4 | 2.1 |
| Sideways scrolling on narrow screens | 1.4.10 | 2.1 |
| Faint input borders and icons | 1.4.11 | 2.1 |
| Layouts that break with custom spacing | 1.4.12 | 2.1 |
| Silent status updates | 4.1.3 | 2.1 |
| Tiny, cramped tap targets | 2.5.8 | 2.2 |
| Focus hidden under sticky headers | 2.4.11 | 2.2 |
If a rule only demands 2.0 AA, build to 2.2 AA anyway. You still meet 2.0, and you avoid a second round of work later. See WCAG versions for how they fit together.
Mobile apps and the 2.0 rules
WCAG 2.0 was written before most of today's phone apps, but it was never limited to desktop browsers. Its criteria apply to mobile websites as they are, and W3C has published guidance notes on applying WCAG 2 to non-web software, which regulators use for native mobile applications. Because 2.0 has no criteria for orientation, gestures or target size, a 2.0 test alone misses common mobile problems.
For phones and tablets, test against 2.2 and follow our WCAG guide for mobile apps.
Testing a page against 2.0 AA
The quickest way to check a page against 2.0 AA is to run the 38 criteria in the WCAG checklist filtered down to the original release. Pair that with one of the automated checkers and a keyboard pass. Here is one classic 2.0 failure and its fix, from guideline 1.3:
Fails 1.3.1: the heading is only bold text.
<p class="big"><b>Delivery options</b></p>Passes: a real heading element.
<h2>Delivery options</h2>Questions people ask
Can I still use WCAG 2.0 today?
Yes. W3C has not withdrawn it and some laws still cite it. W3C does recommend using the newest version, 2.2, for new work, and since 2.2 includes 2.0, nothing is lost.
How many criteria does 2.0 level AA include?
38. That is the 25 level A criteria plus the 13 level AA criteria. The full standard has 61 once you add the 23 at AAA.
Does WCAG 2.0 apply to mobile apps?
Its principles and most of its criteria apply, and regulators use W3C notes to apply WCAG 2 to app software. But 2.0 has nothing on orientation, gestures or target size, so test mobile apps against 2.2.
Is a WCAG 2.0 AA compliant site also 2.1 compliant?
Not necessarily. WCAG 2.1 added 7 level AA and 5 level A criteria that a 2.0 site may fail, such as reflow and non-text contrast. The reverse is true, though: a 2.1 AA site meets 2.0 AA.
What is ISO/IEC 40500?
It is the ISO version of WCAG 2.0, with the same content. Some governments prefer citing ISO standards, so you may see this number in tenders instead of the W3C name.