Success Criteria

WCAG 1.4.3 Contrast (Minimum)

Success Criterion 1.4.3 requires visual text to have a contrast ratio of at least 4.5:1 against its background, or 3:1 for large text. It's a Level AA criterion under Guideline 1.4 (Distinguishable) — one of the few WCAG criteria expressed as an exact, calculable number rather than a qualitative judgment.

The exact thresholds

• 4.5:1 — normal-weight text under 18pt (24px), or under 14pt (18.5px) bold
• 3:1 — large text: 18pt+ regular, or 14pt+ bold

The contrast ratio is calculated from each color's relative luminance, per a formula defined in the WCAG spec itself — this is why automated tools can check this criterion with complete certainty, unlike almost anything else in WCAG.

What's exempt

• Text that's part of an inactive/disabled UI component (a genuinely disabled button, not just styled to look disabled)
• Text that's purely decorative and conveys no information
• Text inside a logo or brand name ("incidental" text)
• Text that happens to appear in a photograph, where the photo itself is the content being conveyed

How this differs from 1.4.6 (Enhanced)

WCAG also defines a stricter AAA-level version of this same idea — 1.4.6 Contrast (Enhanced) — requiring 7:1/4.5:1 instead. 1.4.3's AA-level numbers are what nearly every legal standard and procurement requirement actually mandates; see Conformance Levels Explained for why AAA is rarely required in full.

Practical guidance

See Insufficient Color Contrast for concrete failure patterns (grey-on-white text, low-contrast placeholders, text over photos) and how to fix each one. The short version: verify actual colors against a real contrast calculator rather than eyeballing them — the visual difference between passing and failing a 4.5:1 ratio is often too subtle to judge by eye.

Common questions

What is WCAG 1.4.3 Contrast (Minimum)?

A Level AA criterion requiring a 4.5:1 contrast ratio for normal text and 3:1 for large text between the text color and its background.

What counts as large text?

At least 18pt (24px), or 14pt (18.66px) if bold. Large text only needs a 3:1 ratio instead of 4.5:1.

What is exempt from 1.4.3?

Text in logos or brand names, purely decorative text, and text in inactive or disabled UI components are not required to meet the ratio.