WCAG 2.1 Success Criteria Reference

All non-text content has a text alternative that serves the equivalent purpose. Decorative images can use empty alt text.

Perceivable → Text Alternatives

For prerecorded audio-only, provide a text transcript. For prerecorded video-only, provide a text or audio alternative.

Perceivable → Time-based Media

Captions are provided for all prerecorded audio content in synchronized media.

Perceivable → Time-based Media

An alternative for time-based media or audio description of video content is provided.

Perceivable → Time-based Media

Audio description is provided for all prerecorded video content in synchronized media.

Perceivable → Time-based Media

Information, structure, and relationships conveyed through presentation can be programmatically determined or are available in text.

Perceivable → Adaptable

When the sequence of content affects meaning, a correct reading sequence can be programmatically determined.

Perceivable → Adaptable

Instructions do not rely solely on sensory characteristics such as shape, color, size, visual location, orientation, or sound.

Perceivable → Adaptable

Content does not restrict its view and operation to a single display orientation unless essential.

Perceivable → Adaptable

The purpose of form inputs collecting user information can be programmatically determined using autocomplete attributes.

Perceivable → Adaptable

Color is not used as the only visual means of conveying information, indicating an action, prompting a response, or distinguishing a visual element.

Perceivable → Distinguishable

If audio plays automatically for more than 3 seconds, there is a mechanism to pause/stop or control volume.

Perceivable → Distinguishable

Text and images of text have a contrast ratio of at least 4.5:1. Large text (18pt or 14pt bold) requires 3:1.

Perceivable → Distinguishable

Text can be resized up to 200% without loss of content or functionality, without requiring assistive technology.

Perceivable → Distinguishable

Text is used to convey information rather than images of text, except for customizable images or where essential.

Perceivable → Distinguishable

Content can be presented without loss of information or functionality, and without requiring scrolling in two dimensions, at 320 CSS pixels wide (or 256 CSS pixels tall for horizontal content).

Perceivable → Distinguishable

UI components and graphical objects have a contrast ratio of at least 3:1 against adjacent colors.

Perceivable → Distinguishable

No loss of content when users override text spacing (line height 1.5x, paragraph spacing 2x, letter spacing 0.12em, word spacing 0.16em).

Perceivable → Distinguishable

Content triggered by hover/focus is dismissible, hoverable, and persistent until dismissed.

Perceivable → Distinguishable

All functionality is operable through a keyboard interface without requiring specific timings for individual keystrokes.

Operable → Keyboard Accessible

If keyboard focus can be moved to a component, focus can be moved away using only keyboard without requiring more than arrow keys, Tab, Escape, or other standard methods.

Operable → Keyboard Accessible

If single-character key shortcuts exist, they can be turned off, remapped, or are only active when the component is focused.

Operable → Keyboard Accessible

For time limits, the user can turn off, adjust, or extend the time (with at least 20 seconds warning).

Operable → Enough Time

For moving, blinking, scrolling, or auto-updating content that starts automatically and lasts more than 5 seconds, the user can pause, stop, or hide it.

Operable → Enough Time

Pages do not contain anything that flashes more than three times per second.

Operable → Seizures and Physical Reactions

A mechanism is available to bypass blocks of content that are repeated on multiple pages.

Operable → Navigable

Pages have titles that describe their topic or purpose.

Operable → Navigable

Focusable components receive focus in an order that preserves meaning and operability.

Operable → Navigable

The purpose of each link can be determined from the link text alone, or from the link together with its context.

Operable → Navigable

More than one way is available to locate a page within a set of pages (unless it's a step in a process).

Operable → Navigable

Headings and labels describe topic or purpose.

Operable → Navigable

Any keyboard operable UI has a visible focus indicator.

Operable → Navigable

All multipoint or path-based gestures can be operated with a single pointer without path-based gesture, unless essential.

Operable → Input Modalities

For single-pointer functionality: down-event doesn't trigger action, action is on up-event with ability to abort, up-event reverses down-event, or completing on down-event is essential.

Operable → Input Modalities

For components with visible text labels, the accessible name contains the visible text.

Operable → Input Modalities

Functionality operated by device motion or user motion can also be operated via UI components, and motion can be disabled.

Operable → Input Modalities

The default human language of the page can be programmatically determined.

Understandable → Readable

The language of each passage or phrase can be programmatically determined, except for proper names, technical terms, or indeterminate language.

Understandable → Readable

When a component receives focus, it does not initiate a change of context.

Understandable → Predictable

Changing the setting of a UI component does not automatically cause a change of context unless the user is advised beforehand.

Understandable → Predictable

Navigation mechanisms repeated on multiple pages occur in the same relative order each time.

Understandable → Predictable

Components with the same functionality are identified consistently.

Understandable → Predictable

If an input error is automatically detected, the item in error is identified and the error is described in text.

Understandable → Input Assistance

Labels or instructions are provided when content requires user input.

Understandable → Input Assistance

If an error is detected and suggestions are known, they are provided to the user (unless it would jeopardize security).

Understandable → Input Assistance

For pages with legal/financial/data submissions: submissions are reversible, data is checked before submission, or user can review and confirm.

Understandable → Input Assistance

In content using markup languages, elements have complete start and end tags, are nested correctly, don't contain duplicate attributes, and IDs are unique. (Note: obsoleted in WCAG 2.2 but still in 2.1)

Robust → Compatible

For all UI components, the name and role can be programmatically determined; states, properties, and values can be set by the user and change notifications are available to assistive technologies.

Robust → Compatible

Status messages can be programmatically determined via role or properties so they can be presented by assistive technologies without receiving focus.

Robust → Compatible

Interactive maps that convey geographic information must provide a text-based alternative — such as a data table, downloadable dataset, or text summary — that gives users equivalent access to the spatial data without requiring visual interpretation of the map.

Perceivable → Text Alternatives

Interactive map controls — including zoom buttons, layer toggles, basemap switchers, and popup close buttons — must have a minimum touch target size of 44x44 CSS pixels to be usable on touch devices and by users with motor impairments.

Operable → Input Modalities