Perceivable
Web content is made available to the senses - sight, hearing, and/or touch
Guideline 1.1 Provide text alternatives for any non-text content
- Images, image buttons, and image map hot spots have equivalent alternative text.
- Images that do not convey content, are decorative, or contain content that is already conveyed in text are given empty alternative text.
- All linked images have descriptive alternative text.
- Complex images have equivalent alternatives.
- Form buttons have a descriptive value.
- Inputs have associated accessible names.
- Embedded multimedia is identified via accessible text.
- Frames and iframes are appropriately titled.
Guideline 1.2 Provide alternatives for time-based media.
NOTE: If the media is designated as an alternative to web content (e.g., an audio or sign language version of a web page), then the web content itself serves as the alternative.
- A descriptive transcript" of relevant content is provided for non-live audio-only (audio podcasts, MP3 files, etc.).
- A descriptive transcript or audio description of relevant content is provided for non-live video-only, unless the video is decorative.
- A descriptive transcript or audio description is provided for non-live video.
NOTE: Only required if there is relevant visual content that is not presented in the audio.
- Synchronized captions are provided for live media that contains audio
- Audio descriptions are provided for non-live video.
NOTE: Only required if there is relevant visual content that is not presented in the audio.
- While not required, WebAIM recommends descriptive transcripts in addition to audio descriptions.
Guideline 1.3
Create content that can be presented in different ways (for example simpler layout) without losing information or structure.
- Semantic markup is appropriately used to designate headings, regions/landmarks, lists, emphasized or special text.
- Tables are used for tabular data and data cells are associated with their headers. Data table captions, if present, are associated to data tables.
- Text labels are associated with form inputs. Related form controls are grouped with fieldset/legend. ARIA labelling may be used when standard HTML is insufficient.
- Instructions do not rely upon shape, size, or visual location (e.g., "Click the square icon to continue" or "Instructions are in the right-hand column").
- Instructions do not rely upon sound (e.g., "A beeping sound indicates you may continue.").
- Orientation of web content is not restricted to only portrait or landscape, unless a specific orientation is necessary.
Guideline 1.4
Make it easier for users to see and hear content
- Color is not used as the sole method of conveying content or distinguishing visual elements.
- Color alone is not used to distinguish links from surrounding text unless the contrast ratio between the link and the surrounding text is at least 3:1 and an additional distinction (e.g., it becomes underlined) is provided when the link is hovered over and receives keyboard focus.
- A mechanism is provided to stop, pause, mute, or adjust volume for audio that automatically plays on a page for more than 3 seconds.
- Text and images of text have a contrast ratio of at least 4.5:1.
- Large text - at least 18 point (typically 24px) or 14 point (typically 18.66px) and bold - has a contrast ratio of at least 3:1.
- The page is readable and functional when the page is zoomed to 200%. NOTE: 1.4.10 (below) introduces additional requirements for zoomed content.
- If the same visual presentation can be made using text alone, an image is not used to present that text.
- No loss of content or functionality occurs, and horizontal scrolling is avoided when content is presented at a width of 320 pixels.
- This requires responsive design for most web sites. This is best tested by setting the browser window to 1280 pixels wide and then zooming the page content to 400%.
- Content that requires horizontal scrolling, such as data tables, complex images (such as maps and charts), toolbars, etc. are exempted.
- A contrast ratio of at least 3:1 is used to differentiate graphical objects (such as icons and components of charts or graphs) and interface components (such as buttons, form controls, and focus indicators/outlines).
- At least 3:1 contrast is maintained in the various states (focus, hover, active, etc.) of author-customized interactive components.
- No loss of content or functionality occurs when the user adapts paragraph spacing to 2 times the font size, text line height/spacing to 1.5 times the font size, word spacing to .16 times the font size, and letter spacing to .12 times the font size.
- This is best supported by avoiding pixel height definitions for elements that contain text.
- When additional content is presented on hover or keyboard focus:
- The revealed content can be dismissed (generally via the Esc key) without moving the pointer or keyboard focus, unless the content presents an input error or does not obscure or interfere with other page content.
- The pointer can be moved to the new content without the content disappearing.
- The new content must remain visible until the pointer or keyboard focus is moved away from the triggering control, the new content is dismissed, or the new content is no longer relevant.
Operable
Interface forms, controls, and navigation are operable.
Guideline 2.1 All functionality is available from a keyboard.
- All page functionality is available using the keyboard, unless the functionality cannot be accomplished using a keyboard (e.g., free hand drawing).
- Page-specified shortcut keys and access keys (access keys should typically be avoided) do not conflict with existing browser and screen reader shortcuts.
- Keyboard focus is never locked at one particular page element. The user can navigate to and from all navigable page elements using only a keyboard.
- All page functionality is available using the keyboard.
- If a keyboard shortcut uses printable character keys, then the user must be able to disable the key command, change the defined key to a non-printable key (Ctrl, Alt, etc.), or only activate the shortcut when an associated interface component or button is focused.
Guideline 2.2 Provide users enough time to read and use content.
- If a page or application has a time limit, the user is given options to turn off, adjust, or extend that time limit. This is not a requirement for real-time events (e.g., an auction), where the time limit is absolutely required, or if the time limit is longer than 20 hours.
- Automatically moving, blinking, or scrolling content (such as carousels, marquees, or animations) that lasts longer than 5 seconds can be paused, stopped, or hidden by the user.
- Automatically updating content (e.g., a dynamically-updating news ticker, chat messages, etc.) can be paused, stopped, or hidden by the user.
Guideline 2.3 Do not design content in a way that is known to cause seizures.
Guideline 2.4 Provide ways to help users navigate and find content.
- A link is provided to skip navigation and page elements that are repeated across web pages.
- While proper use of headings or regions/landmarks is sufficient to meet this criterion, because keyboard navigation by headings or regions is not supported in most browsers, WebAIM recommends a "skip" link in addition to headings and regions.
- The web page has a descriptive and informative page title.
- The navigation order of links, form controls, etc. is logical and intuitive.
- The purpose of each link (or image button or image map hotspot) can be determined from the link text alone, or from the link text and its context (e.g., surrounding text, list item, previous heading, or table headers).
- Links with the same text that go to different locations are readily distinguishable.
- Multiple ways are available to find other web pages on the site - at least two of: a list of related pages, table of contents, site map, site search, or list of all available web pages.
- Page headings and labels for form and interactive controls are informative. Avoid duplicating heading and label text unless the structure provides adequate differentiation.
- There is a visible indicator for page elements when they receive keyboard focus.
Guideline 2.5 Make it easier for users to operate functionality through inputs beyond keyboard.
- If multipoint or path-based gestures (such as pinching, swiping, or dragging) are not essential to the functionality, then the functionality can also be performed with a single point activation (such as activating a button).
- To help avoid inadvertent activation of controls, avoid non-essential down-event activation when clicking, tapping, or long pressing the screen. For complex interactions (such as drag and drop),
onmousedown can be used if an associated onmouseup event can be aborted or reversed.
- If an interface component (link, button, etc.) presents text (or images of text), the accessible name (label, alternative text, aria-label, etc.) for that component must include the visible text.
- Functionality that is triggered by moving the device (such as shaking or panning a mobile device) or by user movement (such as waving to a camera) can be disabled and equivalent functionality is provided via standard controls.
Understandable
Information and the operation of user interface must be understandable.
Guideline 3.1 Make text content readable and understandable.
- The language of the page is identified using the
lang attribute (e.g., <html lang="en">).
- The language of page content that is in a different language is identified using the
lang attribute (e.g., <blockquote lang="es">).
Guideline 3.2 Make Web pages appear and operate in predictable ways.
- When a page element receives focus, it does not result in a substantial change to the page, the spawning of a pop-up window, an additional change of keyboard focus, or any other change that could confuse or disorient the user.
- When a user inputs information or interacts with a control, it does not result in a substantial change to the page, the spawning of a pop-up window, an additional change of keyboard focus, or any other change that could confuse or disorient the user unless the user is informed of the change ahead of time.
- Navigation links that are repeated on web pages do not change order when navigating through the site.
- Elements that have the same functionality across multiple web pages are consistently identified. For example, a search box at the top of the site should always be labeled the same way.
Guideline 3.3 Help users avoid and correct mistakes.
- Required inputs or inputs that require a specific format, value, or length provide this information within the element's label.
- Form validation errors are efficient, intuitive, and accessible. The error is clearly identified, quick access to the problematic element is provided, and the user can easily fix the error and resubmit the form.
- Inputs are identified by labels or instructions that help users know what information to enter.
- If an input error is detected, suggestions are provided for fixing the input in a timely and accessible manner.
- Submissions, changes, and deletions of legal, financial, or test data can be reversed, verified, or confirmed.
Robust
Content must be robust enough that it can be interpreted reliably by a wide variety of user agents, including assistive technologies.
Guideline 4.1 Maximize compatibility with user agents, including assistive technologies.
- Markup is used in a way that facilitates accessibility. This includes following the HTML specifications and using forms, input labels, and frame titles appropriately.
- ARIA is used to enhance accessibility when HTML is not sufficient.
- If an important status message is presented and focus is not set to that message, the message must be announced to screen reader users, typically via an ARIA alert or live region.
This checklist is provided as a resource to help implement Web Content Accessibility Guidelines (WCAG) 2.2 (W3C Recommendation), which is Copyright © 2017-2023 W3C®.