Web Content Accessibility Guidelines 2.1

WCAG 2.1 guidelines are categorised into three levels of conformance in order to meet the needs of different groups and different situations: A (lowest), AA (mid range), and AAA (highest). Conformance at higher levels indicates conformance at lower levels.

This page lists guidelines for Level A and Level AA. From W3C WCAG 2.1 Quick Reference.

Principle 1 – Perceivable

1.1 Provide text alternatives for non-text content (e.g. images)

1.1.1 Provide text alternatives for non-text content (e.g. images). Level A

1.2 Provide alternatives for time-based media (audio and video)

1.2.1 Provide alternatives for pre-recorded audio-only or video-only content. Level A

1.2.2 Provide captions for pre-recorded audio. Level A

1.2.3 Provide alternatives for pre-recorded synchronized audio/video Level A

1.2.4 Provide captions for live audio in synchronized audio/video. Level AA

1.2.5 Provide an audio description of pre-recorded video. Level AA

1.3 Content can be presented in different ways (e.g. through a screen reader) without losing info or structure

1.3.1 Information, structure, and relationships can be programmatically determined. Level A

1.3.2 The correct reading sequence can be programmatically determined. Level A

1.3.3 Do not rely solely on sensory characteristics of components such as shape, size, visual location, orientation, or sound. Level A

1.3.4 Do not restrict a page’s view to a single display orientation, such as portrait or landscape, unless a specific orientation is essential. Level AA

1.3.5 The purpose of each input field collecting information about the user can be programmatically determined. Level AA

1.4 Make sure content is readable and the foreground contrasts sufficiently with the background

1.4.1 Colour is not used as the only visual means of conveying info. Level A

1.4.2 Audio can be paused and stopped, or the audio volume can be changed. Level A

1.4.3 Text has enough contrast with the background (contrast ratio 4:5:1 for small text and 3:1 for large text). Level AA

1.4.4 Text can be enlarged up to 200% without the use of assistive technology (screen magnifiers). Level AA

1.4.5 Text is used rather than images of text, except where the presentation of text is essential, such as in logos. Level AA

1.4.10 When content is zoomed in to a large degree, the site will adapt to ensure that scrolling only occurs in one direction. Level AA

1.4.11 Visual objects must have a contrast ratio of 3:1 against adjacent colour(s). Level AA

1.4.12 Text spacing CSS settings can be changed to certain minimum values without loss of content or functionality. Level AA

1.4.13 Content that appears on mouse hover or focus must be dismissable, hoverable, and persistent. Level AA

Principle 2 – Operable

2.1 Make all functionality available from a keyboard

2.1.1 All functionality is available from a keyboard, except for tasks such as drawing. Level A

2.1.2 The user can use the keyboard to move through page elements and is not trapped on a particular element. Level A

2.1.4 If single character key shortcuts are used, then they can either be turned off, remapped, or are only active when the shortcut for a UI component has focus. Level A

2.2 Give users enough time to read and use content

2.2.1 Users are warned of time limits shorter than 20 hours and time limits can be turned off or extended. Level A

2.2.2 Users can stop, pause or hide moving, blinking, scrolling or auto-updating information. Level A

2.3 Do not use content that can cause seizures

2.3.1 No more than three flashes in a 1- second period, or the flashes are below the defined thresholds. Level A

2.4 Help users to navigate, find content, and determine where they are

2.4.1 Users can bypass blocks of content that are repeated on multiple Web pages, such as navigation menus. Level A

2.4.2 The page has a title describing its topic or purpose. Level A

2.4.3 Users can tab through the elements of a page in a logical order. Level A

2.4.4 The purpose of each link can be determined from the link text or context. Level A

2.4.5 More than one way is available to navigate to other Web pages, such as a sitemap. Level AA

2.4.6 The headings and labels are clear and consistent, accurately describing the topic or purpose. Level AA

2.4.7 The page element with the current keyboard focus has a visible focus indicator. Level AA

2.5 Make it easier for users to operate functionality through various inputs beyond keyboard

2.5.1 All operations must use simple gestures that need only a single touch or click. If more complex operations exist, a single touch or click alternative must be given. Level A

2.5.2 Allow users to recover from accidental or erroneous pointer input (touch screen taps, mouse clicks). Level A

2.5.3 For user interface components with visible text, ensure that the accessible name includes the visible text. Level A

2.5.4 Motion input (shaking, orientation change, tilting, etc.) must be accompanied by another means of input (such as a button). Level A

Principle 3 – Understandable

3.1 Text should be readable and understandable

3.1.1 Specify the language (e.g. English) of the Web page. Level A

3.1.2 Specify the language (e.g. English) of each text phrase or passage that is in a language other than the default language specified for the entire Web page. Level AA

3.2 Make Web pages appear and operate in predictable ways

3.2.1 When a UI component receives focus, this does not trigger unexpected actions such as automatically submitting a form, opening a new window or switching focus to another element. Level A

3.2.2 Changing the setting of a checkbox, radio button or other UI component does not trigger unexpected changes in context, such as causing significant changes to the page content or opening a new window. Level A

3.2.3 Navigation menus are in the same location and order on every Web page. Level AA

3.2.4 UI components used across the Web site are identified consistently on every page. Level AA

3.3 Help users to avoid and correct mistakes

3.3.1 Input errors are clearly marked and described to the user. Level A

3.3.2 Items requiring user input are clearly labeled or have clear instructions. Level A

3.3.3 When the user makes an input error, give suggestions for valid input. Level AA

3.3.4 For Web pages that cause legal commitments or financial transactions for the user to occur, that modify or delete user-controllable data in data storage systems, or that submit user test responses: The changes must be reversible, correctable or confirmable by the user. Level AA

Principle 4 – Robust

4.1 Maximise compatibility with assistive technologies (such as screen readers) and future browsers

4.1.1 Use valid, error-free HTML, including unique (non-duplicate) element IDs. Level A

4.1.2 For all UI components, the name, value and role can be programmatically determined. Level A

4.1.3 In content implemented using markup languages, status messages can be programmatically determined through role or properties such that they can be presented to the user by assistive technologies without receiving focus. Level AA