Contrast ratio compares the relative luminance of two colors, from 1:1 (identical) to 21:1 (black on white).
Why it matters
WCAG 2 level AA needs at least 4.5:1 for normal text and 3:1 for large text; level AAA needs 7:1 and 4.5:1.
Source: WCAG 2.1
Contrast ratio compares the relative luminance of two colors, from 1:1 (identical) to 21:1 (black on white).
WCAG 2 level AA needs at least 4.5:1 for normal text and 3:1 for large text; level AAA needs 7:1 and 4.5:1.
Source: WCAG 2.1