Designing Accessible Content
Tim Madle, Associate Creative Director
Web Content Accessibility
Guidelines (WCAG) are a series
of guidelines for making web
content accessible for all users,
especially those with disabilities.
The full current version (2.0) lives here: w3.org/TR/WCAG/
Level A We must satisfy these requirements,
otherwise it will be impossible for one or
more groups to access the web content.
Level AA We should satisfy these requirements,
otherwise some groups will find it difficult to
access the web content.
Level AAA We may satisfy these requirements,
in order to make it easier for some groups
to access the web content.
Of the 38 Level A and AA provisions,
Guideline 1.4.1 Level A
Color should not be the only visual means of conveying essential
information. Recommended strategies include providing text
cues or using patterns in addition to different colors.
Guideline 1.4.3 Level AA
Text should have a contrast ratio1
of at least 4.5 to 1 to
accommodate users with mild visual impairments. Exceptions
include text that is large,2
purely decorative, part of an inactive
interface component or part of a logo.
There are many online tools to check contrast ratio, including snook.ca/technical/colour_contrast/colour.html.
Large text is defined as ≥18px if not bold and ≥14px if bold, for which a 3 to 1 contrast ratio is sufficient.
Guideline 1.4.4 Level AA
Text should be resizable up to 200% for users
with mild visual impairments.1
Many modern browsers provide a zoom function for the entire page to accommodate this.
Guideline 2.3.1 Level A
Content should not be designed in a way known to cause
seizures in users with photosensitive epilepsy. Elements
occupying a significant portion of the display that flash more than
three times in one second should be tested for compliance.1
The Trace Center Photosensitive Epilepsy Analysis Tool (PEAT) is available at trace.wisc.edu/peat/
Guideline 2.4.7 Level AA
Users with motor impairments who rely on the keyboard to
navigate need a clear visual focus indicator.1
Many modern browser’s include built-in support to accommodate this.
Guideline 3.2.4 Level AA
Users with disabilities may develop search strategies to efficiently
navigate a site, so label recurring functions consistently.
Guideline 3.3.2 Level A
Labels or instructions should be included whenever user
input is required, and should be positioned near the elements
Guideline 3.3.2 Level A
Instructions should not depend solely on a user’s ability to see
the content as presented. For example, “Press the button on the
right” requires visual information, while “Press the ‘submit’ button
on the right” does not.
Guideline 1.4.2 Level A
Audio that plays automatically may interfere with screen readers.
Any audio that plays automatically must be less than three
seconds, or provide an easily accessible mechanism to stop it.
Guideline 2.1.1 Level A
Sites should be fully operable using only the keyboard.
Guideline 3.2.3 Level AA
Navigation should appear in a consistent and predictable
order throughout a site so users can efficiently navigate.
Guideline 2.4.3 Level A
When navigating in a sequential order (e.g. via the Tab key),
the focus should follow the natural reading order.
Guidelines 3.2.1, 3.2.2 Level A
Because it can be disorienting, changes of context should not
occur when shifting focus or choosing from a selection, but
rather when the user takes a specific action to do so.
Guideline 3.3.1 Level A
If an input error is detected, the error should be identified and
described to the user in a text form.
Guideline 2.2.2 Level A
Content that moves or automatically updates can cause issues
for those with disabilities. Ways to start and stop such activity
should be provided.
Guideline 2.2.1 Level A
Users with disabilities may require significantly more time to
complete tasks due to limitations in assistive technologies,
so time limits should be avoided whenever possible.1
Exceptions include when the user can turn off, adjust or extend the time limit as needed, when it is a real-time limit (e.g. an online auction),
when the time limit is essential to the activity, or when it is longer than 20 hours.
Guarino Reid, Loretta and Andi Snow-Weaver. “WCAG 2.0 for Designers: Beyond Screen Readers and Captions”
Proceedings of the 13th International Conference on Human-Computer Interaction. Springer-Verlag, 2009. pp. 674-682. v1 July 24, 2013 1:50 PM