WCAG explained in plain English

See it for yourself

A live contrast checker — the same math auditors run, in two color pickers.

13.5 : 1

Pass and fail at each WCAG level and text size
Level	Normal text	Large text
AA	—	—
AAA	—	—

The quick brown fox reads the standards so you do not have to.

How it works

WCAG rests on four ideas with a memorable acronym: POUR. Perceivable is the P, and it asks whether a person can take in what the page is offering at all. Images carry text descriptions for people who cannot see them, videos carry captions for people who cannot hear them, and text sits against its background with enough contrast to be read. The demo above does that last check for real: at level AA the floor is 4.5:1 for normal text and 3:1 for large text.

Operable asks whether a person can actually do things. Every link, button, and menu has to work with a keyboard alone, because plenty of people cannot use a mouse. Targets need to be big enough to hit, nothing should trap your focus, and nothing should demand speed or steadiness you may not have.

Understandable asks whether a person can follow what is going on. Plain wording over jargon, navigation that stays put from page to page, and forms that say what went wrong and how to fix it instead of flashing a red border and wishing you luck.

Robust asks whether the page holds up in your tools, not only in the designer's browser. Clean, well-formed code lets screen readers, magnifiers, voice control, and browser extensions all read the same page and present it their own way. If a page falls apart the moment someone changes how it is displayed, it was never really accessible.

Where it came from

The W3C — the body that keeps the web's shared standards — launched the Web Accessibility Initiative in 1997, when the web was young enough that access could still be built in rather than bolted on. Two years later it published WCAG 1.0, the first shared answer to a question every organization had been improvising on its own: what does an accessible website actually mean?

WCAG 2.0 arrived in 2008 and reorganized everything around the four POUR principles — Perceivable, Operable, Understandable, Robust. That reframing is why the standard has aged so well: instead of naming technologies that would date, it describes what people need and lets the techniques change underneath.

The updates since then track how the web itself changed. WCAG 2.1, in 2018, added criteria for mobile screens and low vision — phones had become how most people read. WCAG 2.2, in 2023, added criteria for visible focus, alternatives to dragging, minimum target sizes, and easier sign-in. Each version builds on the last, so work done against an older one still counts.

Notice the pattern: the standard keeps chasing how people actually use the web, not how designers wish they did.

Who it helps — honestly

This page exists for anyone who has been handed "make it WCAG compliant" as a task and a deadline. The first thing to know is that WCAG comes in three levels of strictness — A, AA, and AAA. A is the bare floor, AAA is the strongest, and AA is the one that matters in practice: when a law or a contract names WCAG, it almost certainly names AA. Our page on the ADA and Title II covers how that plays out in US law.

The second thing to know is that WCAG is a floor, not a ceiling. Passing every criterion means disabled people can use your page — it does not mean they will enjoy it. A page can meet AA and still be cluttered, confusing, and exhausting. Conformance is where the work starts, not where it ends.

The floors are still worth defending, because each one stands in for real people. The contrast ratios in the demo above exist for people with low vision and color blindness, who lose text long before anyone else notices a problem. The keyboard rules exist for people who cannot hold a mouse steady, or hold one at all. Miss a criterion and you are not missing a checkbox — you are locking a specific person out.

So the honest advice is: aim for AA, treat it as the beginning, and check your work against real eyes as well as the arithmetic. Start with your own colors in the checker above — it is the same math an auditor will run, and it takes ten seconds to find out where you stand.

Where Helperbird fits

WCAG is about how sites are built. Helperbird sits on the reader's side of the screen — personal fonts, spacing, contrast, and read-aloud on any page, whatever the site did.

High contrast See any page in the contrast that works for you.

Step-by-step: How to use Helperbird's high contrast features

Questions people ask

What do A, AA, and AAA mean?

Strictness levels. A is the floor, AA is the level laws and contracts almost always require, and AAA is the strongest — often applied to the parts of a page that matter most rather than everything.

What contrast ratio does WCAG require?

For AA: 4.5 to 1 for normal text and 3 to 1 for large text. AAA raises those to 7 to 1 and 4.5 to 1. The checker above does the arithmetic for you.

What is the difference between WCAG 2.1 and 2.2?

2.2, finished in 2023, adds nine criteria — focus visibility, dragging alternatives, bigger click targets, and easier authentication among them — and each version stays backwards compatible with the last.