The difference between A, AA and AAA.

WCAG’s three conformance levels are an ordering of scope, not difficulty: a site conforming to AA also conforms to A, because the levels stack on one another.

These three letters are the most confused thing in accessibility conversations. The common assumption is that AAA is the “best” and therefore the level to target. It is not — the W3C itself explicitly does not recommend targeting AAA for an entire site. Understanding why is also the key to choosing the right target.

What separates the levels

The separation is made by consequence, not difficulty. The answer to “what happens when this criterion is not met” determines the criterion’s level.

1. A — if unmet, content becomes COMPLETELY inaccessible for some user groups. A button that cannot be operated by keyboard, an image without an alternative, a focus trap.
2. AA — if unmet, content stays accessible but becomes seriously hard to use. Low-contrast text is not readable, but it is technically “there.”
3. AAA — meeting it markedly improves the experience for specific user groups, but it is not realistic for every content type.

This is why A cannot be skipped: an A violation locks a user group out of the content entirely. An AA violation does not lock anyone out but makes it unusable in practice. An AAA violation, in most cases, is not a deficiency but a matter of choice.

What level A contains — and what it does not

The scope of level A is narrower than most people assume. In WCAG 2.2, 31 success criteria sit at level A, and nearly all are structural/semantic checks — they look at whether the HTML is written correctly.

What IS in A: alternatives for non-text content, information not carried by color alone, keyboard access, no focus traps, the page language declared, form fields labeled, errors identified, name-role-value integrity.

What is NOT in A — and this is the surprising part: the contrast ratio. 1.4.3 “Contrast (Minimum)” sits at AA. So does the visibility of the focus indicator: 2.4.7 “Focus Visible” is AA. A site targeting only A can publish its body text at 2:1 contrast against its ground and show no focus position while navigating by keyboard — both technically conformant.

A site conforming only to A can be technically conformant with unreadable text and an invisible focus.

This does not make A worthless; it shows what the floor is. The Presidential Circular in Türkiye references level A, and for public sites that is real progress. But as a target, A means “accessible,” not “usable.”

AA: the de facto standard

In practice, AA is the real threshold of accessibility. Public tenders, corporate supplier audits and the European Accessibility Act all reference AA technically. As of 2026 it counts as the de facto standard for public institutions and large-scale businesses.

The items AA brings are the ones that make a site genuinely usable.

1. Contrast (1.4.3) — normal text 4.5:1, large text 3:1.
2. Non-text contrast (1.4.11) — interface component boundaries and meaningful graphics 3:1.
3. Focus visible (2.4.7) — the keyboard focus must always be visible.
4. Focus not obscured (2.4.11) — a sticky header cannot fully cover the focus. New in WCAG 2.2.
5. Target size (2.5.8) — touch targets at least 24×24 CSS pixels. New in WCAG 2.2.
6. Resize text (1.4.4) — no content loss at up to 200% zoom.

The cost of reaching AA is lower than assumed in most projects. The contrast fix is a palette decision; the focus ring is a CSS rule; the target size is a grid decision. All three are a few days of work on an existing site — and zero cost on a new project, because it is built right from the start.

Why AAA is not recommended for a whole site

The W3C’s warning surprises most people. The reason is that some AAA criteria are unrealistic for certain content types — in the guideline’s own words, for some content it is not possible to conform to AAA.

The clearest example is sign language interpretation (1.2.6, AAA). Adding sign language to every prerecorded audio content is a real production cost and can be unaffordable for a small publisher. Likewise 1.4.8 “Visual Presentation” brings a series of typographic constraints from line length to line spacing and can directly conflict with editorial design.

But some AAA items are nearly free. Contrast is the best example: 1.4.6 “Contrast (Enhanced)” asks for 7:1, and in most palettes that is just a color change. This site’s body text measures 18.15:1 against the paper — two and a half times the AAA threshold — and it cost nothing in design.

How to choose the right target

Choosing a level is not a compliance decision but a priority decision. The approach that works in practice is this.

1. Take AA as the floor — non-negotiable. The whole project is built to this level.
2. Collect AAA where it is cheap — contrast, focus appearance, target size. If it costs nothing, take it.
3. Leave AAA where it is expensive — sign language, detailed visual presentation constraints. Write down the reason.
4. Raise the bar in critical flows — in single-path flows like the contact form, checkout or sign-in, going to AAA is proportionate.
5. Document the decision — when it is written which AAA clause was not taken and why, the audit argument is over.

The last item is the most skipped and the most useful in an audit. Saying “we do not target AAA” is not enough; writing which clause you did not take and why shows the difference between a conscious scoping decision and an overlooked defect.

And a reminder: when making a conformance claim, the level must hold for ALL of the claimed scope. If a single page carries an AA violation, the site does not conform to AA. Keeping the scope narrow and truly meeting it is more honest than keeping it wide and meeting it partly.

Is there such a thing as partial conformance

A frequent question: most of the site conforms to AA but a few old pages do not — can we say “we conform to AA”? WCAG’s answer is clear: no. A conformance claim must hold for ALL of the declared scope. If one page violates AA, that scope does not conform to AA.

But narrowing the scope is legitimate. Instead of “this entire site conforms to AA,” saying “this site’s main flows — home, services, contact — conform to AA, the archive section excluded” is both honest and valid. Narrow scope truly met beats wide scope partly met, always.

This distinction is especially useful on large, old sites. Moving a thousand-page corporate site to AA in one pass is unrealistic; moving the conversion paths first — search, product, form, checkout — touches more users and produces a claimable result. The scope is widened later.

Level and budget: what costs how much

The level decision is, in practice, a budget decision, and the costs differ dramatically between items. Two criteria written at the same level can differ tenfold in cost; that is why the generalization “AAA is expensive” is wrong.

1. Nearly free — raising the contrast threshold (a palette decision), thickening the focus ring (a single CSS rule), enlarging the touch target (a grid decision). Zero cost on a new project.
2. Cheap — fixing the heading hierarchy, binding form labels, declaring the page language, building the landmark structure. Hours on an existing site, zero on a new one.
3. Medium — producing and writing an alternative text inventory, wiring error messages to a live region, fixing the keyboard flow end to end. Scales with page count.
4. Expensive — video captions and transcripts, audio description, sign language interpretation. Real production cost; grows linearly with content volume.

This table turns the level debate into a more productive question: not “AA or AAA” but “which item costs how much and touches how many users.” If AAA on contrast is free, take it; if AAA on video is expensive, leave it with its reason written. The decision is per item, not per level.

And on a new project the first two rows of the table cost exactly nothing. This is the most concrete defense of treating accessibility from the start: work that takes hours when done later takes no time when done first.

AAA is not expensive; some AAA items are expensive. The difference makes it possible to decide per item.