Resource guide
Principle 1: Perceivable
Making sure everyone can see, hear, and read your content — regardless of disability, device, or context.
By Calling All Minds·Last updated April 2026
Success criteria
More than any other WCAG principle.
Level A
Essential baseline criteria.
Level AA
The legal compliance target.
Level AAA
Enhanced accessibility criteria.
Principle 1
About this principle
The Perceivable principle is about making sure that all the information on your website can actually be perceived by your users, regardless of whether they can see, hear, or process information in the way your design assumes.
If someone is blind, they cannot see images, so those images need text descriptions. If someone is Deaf, they cannot hear audio, so videos need captions. If someone has low vision, they need sufficient contrast between text and background. If someone has a cognitive disability, content needs to be presentable in ways that do not overwhelm.
This principle contains the most criteria of any WCAG principle — 29 in total — covering everything from basic alt text to complex media alternatives, colour contrast, text spacing, and responsive layouts. It is where most accessibility journeys begin and where the most common failures are found.
Where to start
If you are new to WCAG, fix colour contrast (1.4.3) and missing alt text (1.1.1) first. These are the two most common failures and together affect the widest range of users.
Guideline 1.1
Text Alternatives
Provide text alternatives for any non-text content so that it can be changed into other forms people need, such as large print, braille, speech, symbols, or simpler language.
Text Alternatives
Every non-text element needs a text equivalent that serves the same purpose.
1.1.1 Non-text Content (A) — All non-text content that is presented to the user has a text alternative that serves the equivalent purpose. This covers images, icons, charts, CAPTCHAs, controls, and decorative content.
Guideline 1.2
Time-based Media
Provide alternatives for time-based media such as audio and video.
Time-based Media
Audio and video content must have accessible alternatives.
Guideline 1.3
Adaptable
Create content that can be presented in different ways — including assistive technologies — without losing information or structure.
Adaptable
Content must not rely on visual presentation alone to convey meaning.
Guideline 1.4
Distinguishable
Make it easier for users to see and hear content, including separating foreground from background.
Distinguishable
Users must be able to distinguish content from its background and resize it without loss.
Most common failure
Low colour contrast (1.4.3) is the single most common WCAG failure on the web. Text must have a contrast ratio of at least 4.5:1 against its background (3:1 for large text). Use a contrast checker before signing off any design.
AXS Audit
AXS Audit evaluates your website against the full WCAG 2.2 matrix — visual, cognitive, and keyboard criteria that most automated scanners miss. Built by the same team that created this guide.