WCAG 2.2 · Principle 1 of 4
Perceivable
Can somebody who cannot see the screen, or cannot hear it, still get what is on it?
Perceivable is the first test any page has to pass. Information has to arrive in a form the reader can take in, which means it cannot be locked to one sense. A photo carries nothing to a screen reader user until words are attached to it. A video carries nothing to a deaf viewer until it is captioned. Gray text on white carries nothing to eyes that cannot separate the two. If the content does not arrive at all, the other three principles never get a turn.
An audit tests 20 rules under this principle, and 11 of them are Level AA, which is more Level AA than any other principle carries. That is why a report on an ordinary marketing site comes back weighted toward Perceivable even when the keyboard work is worse. Nine more sit at Level AAA, above the level almost every law names. And Perceivable itself is not something you can fail. Neither is a guideline. Conformance is defined against the individual success criteria, and only for whole pages, so a finding always lands on a numbered rule rather than on a principle.
- Rules
- 20
- Level A
- 9
- Level AA
- 11
- Human testing only
- 9
All 20 Perceivable rules, by guideline
1.1 Text Alternatives· Anything that is not text needs words attached, because text can be read, spoken, or felt.
1.2 Time-based Media· Audio and video need captions, transcripts, and description, because sound and picture do not reach everyone.
- 1.2.1Level AAudio-only and Video-only (Prerecorded)A recording with only sound needs a text alternative carrying the same information.Human testing6 fixes
- 1.2.2Level ACaptions (Prerecorded)Every prerecorded video with sound needs synchronized captions.Partly scannable8 fixes
- 1.2.3Level AAudio Description or Media Alternative (Prerecorded)Where a video shows something that matters and never says it out loud, WCAG 1.2.3 gives you a choice.Human testing13 fixes
- 1.2.4Level AACaptions (Live)A live event carrying sound alongside pictures or slides needs captions while it is happening.Human testing5 fixes
- 1.2.5Level AAAudio Description (Prerecorded)At Level AA the text alternative stops being an option.Human testing11 fixes
1.3 Adaptable· Structure has to live in the code, not only in the way the page looks.
- 1.3.1Level AInfo and RelationshipsWhatever a sighted reader works out from the way a page looks has to be recoverable another way.Partly scannable52 fixes
- 1.3.2Level AMeaningful SequenceWhen the order content is presented in affects what it means, a correct reading order has to be recoverable from the code.Human testing12 fixes
- 1.3.3Level ASensory CharacteristicsInstructions for understanding or operating a page cannot lean only on how something looks, where it sits, which way it is turned, or what it sounds like.Human testing3 fixes
- 1.3.4Level AAOrientationContent must not restrict its view and its operation to one screen orientation, unless that orientation is essential.Partly scannable3 fixes
- 1.3.5Level AAIdentify Input PurposeA field collecting information about the person filling in the form has to declare what it is for, in code, using one of 53 defined purposes.Scanner-detectable2 fixes
1.4 Distinguishable· Content has to be easy to see and hear as it ships, with no adjustment needed.
- 1.4.1Level AUse of ColorColor cannot be the only visual thing telling you something.Human testing9 fixes
- 1.4.2Level AAudio ControlIf any audio on a page plays by itself for more than three seconds, you owe the user one of two things.Partly scannable5 fixes
- 1.4.3Level AAContrast (Minimum)Text needs a contrast ratio of at least 4.5:1 against its background.Scanner-detectable7 fixes
- 1.4.4Level AAResize TextText has to survive being enlarged to 200% without losing content or function, and without assistive technology.Partly scannable15 fixes
- 1.4.5Level AAImages of TextWhere the technology can produce the visual presentation you want, use real text rather than a picture of text.Human testing9 fixes
- 1.4.10Level AAReflowAt 320 CSS pixels wide, content has to work without scrolling in two directions at once.Partly scannable11 fixes
- 1.4.11Level AANon-text ContrastTwo things owe 3:1 against the colors next to them.Partly scannable6 fixes
- 1.4.12Level AAText SpacingSet line height to 1.5 times the font size, spacing after paragraphs to 2 times, letter spacing to 0.12 times and word spacing to 0.16 times.Partly scannable6 fixes
- 1.4.13Level AAContent on Hover or FocusContent that appears on hover or focus and then goes away has to satisfy three conditions.Human testing2 fixes
What Perceivable actually covers
Whether the information actually arrives. If somebody cannot see the image, hear the video, or read the text at the size they need, nothing else about the page has happened yet.
Four guidelines carry it. Text alternatives put words behind anything that is not text. Time-based media covers audio and video. Adaptable asks that structure survive a change of presentation. Distinguishable asks that the default presentation be legible and audible as it ships.
Only the last of those four constrains what you already publish. The other three ask you to supply something extra. That is why Distinguishable is where most of the findings land, and why it holds nine of this principle's twenty audited rules on its own.
What fails most here
Text that misses the contrast threshold, almost always in a state nobody measured.
Body copy gets checked and the rest does not. Placeholder text, hover states, focus states and low-emphasis captions all skip the measurement, and the failures pile up in those corners. The standard does grant exceptions and they are narrower than people assume. Text in an inactive control is exempt, so a grayed-out button reading short is not a finding, and so are pure decoration, text nobody can see, and text forming part of a picture that carries other meaning. Logotypes are exempt as well. Large text is not an exception at all, only a lower bar at 3:1.
Who notices first
- People with low vision, who need contrast and the ability to enlarge text without losing content off the side of the screen.
- Blind screen reader users, for whom a missing text alternative does not degrade the content. It deletes it.
- Deaf and hard-of-hearing people, for whom captions are the content rather than an extra on top of it.
- People with color blindness, who lose any meaning your page carries in color and nothing else.
- People with light sensitivity, whose needs run the other way, because a page cranked to maximum contrast can be unreadable to them.
The common misreading
“Perceivable is mostly for blind users.”
Most of it has nothing to do with blindness. Contrast, resize, reflow, text spacing and audio control all live here, and they serve low vision, color blindness, deafness and ordinary aging far more than they serve screen readers. Vision starts declining around age 40 for most people, and almost none of them would describe that as a disability.
The other three principles
- OperableCan everyone navigate and act, keyboard included?
- UnderstandableCan everyone follow what things mean and do?
- RobustDoes it hold up in screen readers and assistive tech?
Or browse by conformance level: Level A · Level AA · or the full 55-rule library.
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