What is WCAG?
WCAG is written by the World Wide Web Consortium (W3C), the group that sets standards for the web. It is made of testable rules called success criteria. Each one describes something a page must do, such as giving images a text alternative or letting people use every control with a keyboard.
| Version | Published | What changed |
|---|---|---|
| WCAG 2.0 | 11 December 2008 | The original WCAG 2 rules |
| WCAG 2.1 | 5 June 2018 | Added 17 success criteria |
| WCAG 2.2 | 5 October 2023, updated 12 December 2024 | Added 9 success criteria and removed 1 |
WCAG 2.2 is also an ISO standard, ISO/IEC 40500:2025. A future WCAG 3 is being written, but it is still an early draft and not ready to use as a standard.
What are the four principles of WCAG?
Every WCAG rule sits under one of four principles, often shortened to POUR:
- Perceivable: people must be able to take in the content. Examples are alt text for images, captions for video and enough color contrast.
- Operable: people must be able to use the controls and navigation. Examples are full keyboard access, enough time to act, and no flashing that could cause seizures.
- Understandable: content and controls must make sense. Examples are clear language, menus that behave the same way on every page, and helpful form errors.
- Robust: content must work with many browsers and assistive technologies, such as screen readers. This mostly comes down to clean, standard code.
What do WCAG levels A, AA and AAA mean?
| Level | What it means | Examples |
|---|---|---|
| A | The basics. Without these, some people can't use the page at all. | Text alternatives for images, keyboard access, no keyboard traps |
| AA | The common target. It removes the biggest barriers for most people. | Text contrast of at least 4.5:1, text that zooms to 200%, a visible keyboard focus |
| AAA | The highest level. Not all content can meet it. | Text contrast of at least 7:1, sign language for pre-recorded video |
Levels build on each other. To conform at Level AA, a page must meet every Level A and every Level AA success criterion. The W3C does not recommend requiring Level AAA for whole sites, because some content can't meet every AAA rule.
What does WCAG AA mean in practice?
- Normal text has a contrast ratio of at least 4.5:1 with its background, and large text at least 3:1. Test your colors with our color contrast checker.
- Text can be zoomed to 200% without losing content, and pages work on a narrow screen without scrolling in two directions.
- Everything works with a keyboard, nothing traps the keyboard, and you can always see where the focus is.
- Images have useful text alternatives, and pre-recorded videos have captions and audio description.
- Form fields have labels, and error messages explain how to fix the problem.
- Buttons and links are at least 24 by 24 CSS pixels, or have enough space around them.
Laws name different versions. The US rule for state and local government websites uses WCAG 2.1 AA. Section 508 and Ontario's AODA use WCAG 2.0 AA. The European standard EN 301 549 is based on WCAG 2.1 AA, and its September 2026 update moves to WCAG 2.2.
What is new in WCAG 2.2?
WCAG 2.2 added nine success criteria. Six of them are at Level A or AA, so they matter for most sites.
| Success criterion | Level | In plain words |
|---|---|---|
| 2.4.11 Focus Not Obscured (Minimum) | AA | The item with keyboard focus isn't completely hidden, for example by a sticky header or cookie banner. |
| 2.4.12 Focus Not Obscured (Enhanced) | AAA | No part of the focused item is hidden. |
| 2.4.13 Focus Appearance | AAA | The focus indicator is big enough and has enough contrast. |
| 2.5.7 Dragging Movements | AA | Anything you can do by dragging can also be done with a single click or tap. |
| 2.5.8 Target Size (Minimum) | AA | Click and tap targets are at least 24 by 24 CSS pixels, with some exceptions. |
| 3.2.6 Consistent Help | A | Help options, such as contact details or a chat link, appear in the same place on each page. |
| 3.3.7 Redundant Entry | A | People aren't asked to type the same information twice in one process. |
| 3.3.8 Accessible Authentication (Minimum) | AA | Logging in doesn't depend on remembering a password or solving a puzzle, unless there is help, such as allowing password managers and paste. |
| 3.3.9 Accessible Authentication (Enhanced) | AAA | A stricter version of 3.3.8 with fewer exceptions. |
WCAG 2.2 also removed one rule, 4.1.1 Parsing, which the W3C now treats as obsolete.
What is the difference between WCAG 2.1 and 2.2?
WCAG 2.2 keeps the 2.1 rules, adds the nine criteria above and drops 4.1.1 Parsing. The W3C says content that conforms to 2.2 also conforms to 2.1 and 2.0, and recommends using the latest version. So aiming for 2.2 AA also covers a law that asks for 2.1 AA.
How do you test a website against WCAG?
No single tool can tell you whether a site meets WCAG. A good test mixes methods:
- Run an automated checker to catch common problems, such as missing alt text or low contrast.
- Put the mouse away and press Tab to move through each page. Our keyboard accessibility guide explains what to look for.
- Zoom the browser to 200% and check that nothing is cut off or overlaps.
- Listen to key pages with a screen reader, such as VoiceOver or NVDA.
- Ask people with disabilities to try real tasks, such as signing up or checking out.
Our website accessibility checklist turns these steps into a simple list. A visitor tool such as Octo Assist can give people extra display options, but it doesn't change whether your own code passes WCAG.
Frequently asked questions
What is the latest version of WCAG?
The latest version is WCAG 2.2. The W3C published it on 5 October 2023 and updated it on 12 December 2024. WCAG 3 is being written but is still an early draft.
Is WCAG a law?
No, WCAG is a technical standard, not a law. But many laws point to it, and most name Level AA of WCAG 2.0, 2.1 or 2.2. In Europe, the EN 301 549 standard is based on WCAG.
Should I follow WCAG 2.1 or WCAG 2.2?
Aim for WCAG 2.2 Level AA. The W3C says content that conforms to 2.2 also conforms to 2.1 and 2.0, so you meet the older versions too, and it recommends using the latest version.
What contrast ratio does WCAG AA require?
WCAG AA requires a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text. Large text means at least 18 point, or 14 point bold. Icons and the edges of form fields need at least 3:1 against the colors next to them.