Contrast Game

Guess how accessible color contrasts are

Guess whether the shown text has sufficient contrast to the background to be readable according to either the WCAG 2.0 or APCA algorithm.

WCAG 2.0 Color Contrast Algorithm
The WCAG 2.0 algorithm require a minimum contrast ratio of 4.5:1 for normal text and 7:1 for enhanced accessibility, corresponding to AA and AAA compliance levels, respectively. These guidelines are official and widely recognized as the standard for web accessibility, but they only consider luminance (brightness) differences between text and background, without accounting for human color perception.
APCA Color Contrast Algorithm
APCA (Accessible Perceptual Contrast Algorithm) takes both brightness and color perception into account, with contrast requirements based on text size and weight. It uses levels ranging from 0 (Fail) to 4 (highest accessibility), with a recommended contrast score of 90 for 16px text at a weight of 400 to achieve level 4. APCA was briefly included in draft documents for WCAG 3.0 but has since been removed.