Level AAWCAG 2.2

1.4.3 Contrast (Minimum)

Text and images of text have a contrast ratio of at least 4.5:1.

Why it matters

Low vision
More than 2.2 billion people worldwide have a vision impairment. Low-contrast text is almost invisible to them.
Environmental factors
Even users with typical vision struggle to read low-contrast text in direct sunlight.
Aging
Contrast sensitivity declines after age 50. Studies show it can drop to half by age 75.
Mobile
Small screens, glare, outdoor use — contrast matters more than ever.

Success criteria

Normal text: 4.5:1 or higher

Large text (18pt+ or 14pt+ bold): 3:1 or higher

Exceptions: decorative text, logos, inactive UI

Formula: (L1 + 0.05) / (L2 + 0.05). Maximum 21:1 (black and white), minimum 1:1 (same color).

Live demo

Color contrast comparison

Aa 12
white × light gray
1.6:1
Aa 12
green × green
1.2:1
Aa 12
yellow × white
1.1:1

Try the contrast level

Move the slider to change the text lightness and feel how readability changes.

Can you read this text?

Accessibility is for everyone.

70%
Approx. 2.0:1 — Fails AA (below 4.5:1)

Understand through a persona

Tanaka (68) — Age-related macular degeneration

Her central vision is blurred and faint gray text blends into the background. On sites with at least 4.5:1 she can read without a magnifier. 'If I can't read the hospital booking site, I have no choice but to call.'

Checklist

References