WCAG 2.2 / RULE REFERENCE

WCAG 1.4.3 — Contrast minimum

Contrast minimum is the most commonly failed machine-detectable criterion on the web — WebAIM’s Million report finds low-contrast text on the majority of homepages year after year. It is Level AA, the EN 301 549 conformance target, and it is uniquely fixable at the token layer: one low-contrast slate in a design system’s palette fails every component that inherits it.

The rule

Text needs 4.5:1 contrast against its background (3:1 for large text). Level AA — the most common machine-detectable failure on the web.

What it means for how you build

Fix it in the design tokens, not page by page — one low-contrast slate on a brand palette fails every page that uses it.

Self-check

Do all text/background pairs clear 4.5:1 — 3:1 for large text (≥18pt or ≥14pt bold)?
Does placeholder text pass? Placeholders count as text.
Do hover, focus, and disabled states hold — states change computed contrast?
Are ratios verified on rendered output, not just the design file?

Common pitfalls

The default gray: a #999-on-white "subtle" slate is the most common failure pattern in design systems.
Text over imagery: a scrim that passes in the mockup fails at the image’s light edges.
axe alone is not conclusive — contrast over gradients and images needs visual judgement, not just DOM pairs.

How the engine checks it

axe contrast checks inside the Tier-2 audit run, rolled up into the criterion-level conformance report.

Sources

Related rules

Last reviewed 2026-11-01.