WCAG AA vs AAA: Which Contrast Level Do You Need?

WCAG defines three conformance levels — A, AA, and AAA — and for color contrast the practical question is almost always the same: is AA enough, or should I target AAA? Short answer: AA is the standard you must hit; AAA is a quality bar worth hitting where it’s cheap. Here’s the reasoning.

What each level requires for contrast

“Large” has a precise definition: at least 24px regular weight, or 18.66px bold (WCAG says 18pt/14pt; browsers render 1pt as 1.333px). A 20px semibold headline is not large text — when in doubt, hold it to 4.5:1.

Why AA is the default

AA is what regulations point at. The ADA (through court practice and DOJ rulemaking), Section 508 in the US, the European Accessibility Act and EN 301 549 in the EU, and most national laws reference WCAG 2.1 or 2.2 Level AA as the compliance bar. Nobody legally requires AAA across a whole site — the W3C itself says full-site AAA “is not recommended… as a general policy” because some content can’t satisfy it.

When AAA is worth it

• Long-form reading — documentation, articles, anything people read for minutes at a time. 7:1 body text noticeably reduces fatigue, including for aging eyes; the audience over 60 is everyone’s fastest-growing user segment.
• Content for known low-vision audiences — healthcare, government services, banking.
• Wherever it costs nothing. Near-black on near-white is already 15:1+. If your palette naturally clears 7:1, take the AAA badge — don’t lighten grays for style points until they scrape 4.6:1.

A practical policy

1. AA everywhere, verified, no exceptions. Every text/background pair, every icon, every focus ring. This is the floor, not the goal.
2. AAA for body text on reading-heavy pages.
3. Don’t chase AAA for UI chrome — for large headings, buttons, and badges, AA plus a clear focus style helps users more than two extra points of ratio.