WCAG 2.1 Perceivable: Every Success Criterion Explained

This is educational technical reference content, not legal advice. It explains what WCAG 2.1 requires and how to meet it — not whether a specific site carries legal risk. Compliance with WCAG, the ADA, or any other accessibility law or standard is a legal determination; consult qualified counsel for legal risk assessment.

WCAG 2.1 guidelines hub → Perceivable

The Perceivable principle is the first of WCAG 2.1’s four principles: information and user interface components must be presentable to users in ways they can perceive — meaning it can’t be invisible to all of a user’s senses at once. In practice, this is the principle that governs alt text, captions, color contrast, text resizing, and whether your layout survives zoom and reflow. It has four guidelines and 29 success criteria, from Level A (the baseline) through AA (Quietramp’s audit standard) to AAA (the strictest tier, rarely mandated but useful to know).

This page covers every Perceivable success criterion in WCAG 2.1, in order — each one now has its own dedicated page linked below. Numbers, names, and levels are drawn from the official WCAG 2.1 quick reference, which is the source to check for current normative wording. See also our companion page on the Operable principle.

Contents

Every success criterion below now has its own dedicated page — the list here is grouped by guideline for quick scanning.

1.1 Text Alternatives

• 1.1.1 Non-text Content (Level A)

1.2 Time-based Media

• 1.2.1 Audio-only and Video-only (Prerecorded) (Level A)
• 1.2.2 Captions (Prerecorded) (Level A)
• 1.2.3 Audio Description or Media Alternative (Prerecorded) (Level A)
• 1.2.4 Captions (Live) (Level AA)
• 1.2.5 Audio Description (Prerecorded) (Level AA)
• 1.2.6 Sign Language (Prerecorded) (Level AAA)
• 1.2.7 Extended Audio Description (Prerecorded) (Level AAA)
• 1.2.8 Media Alternative (Prerecorded) (Level AAA)
• 1.2.9 Audio-only (Live) (Level AAA)

1.3 Adaptable

• 1.3.1 Info and Relationships (Level A)
• 1.3.2 Meaningful Sequence (Level A)
• 1.3.3 Sensory Characteristics (Level A)
• 1.3.4 Orientation (Level AA)
• 1.3.5 Identify Input Purpose (Level AA)
• 1.3.6 Identify Purpose (Level AAA)

1.4 Distinguishable

• 1.4.1 Use of Color (Level A)
• 1.4.2 Audio Control (Level A)
• 1.4.3 Contrast (Minimum) (Level AA)
• 1.4.4 Resize Text (Level AA)
• 1.4.5 Images of Text (Level AA)
• 1.4.6 Contrast (Enhanced) (Level AAA)
• 1.4.7 Low or No Background Audio (Level AAA)
• 1.4.8 Visual Presentation (Level AAA)
• 1.4.9 Images of Text (No Exception) (Level AAA)
• 1.4.10 Reflow (Level AA)
• 1.4.11 Non-text Contrast (Level AA)
• 1.4.12 Text Spacing (Level AA)
• 1.4.13 Content on Hover or Focus (Level AA)

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This is educational technical reference content, not legal advice. It explains what WCAG 2.1 requires and how to meet it — not whether a specific site carries legal risk. Compliance with WCAG, the ADA, or any other accessibility law or standard is a legal determination; consult qualified counsel for legal risk assessment.

This page was drafted with AI assistance and reviewed by a person for accuracy before publication.

↑ Back to the WCAG 2.1 guidelines hub · Continue to WCAG 2.1 Operable: Every Success Criterion Explained, or see how a real audit catches what automated scanning misses in a sample report.