TermCraft conventionFoundational
Contrast Ratio
A number saying how easy text is to read against its background.
Definition
A numeric measure of the luminance difference between two colours, from 1:1 to 21:1.
Craft convention. True because the industry converged on it. Breaking it costs familiarity, not correctness.
In plain language
A number saying how easy text is to read against its background.
Example
Body text needs 4.5:1 against its background to meet WCAG AA.
Continue from here
Each link says what the connection is, so you can tell a principle from an alternative from a thing people mix this up with.
Deeper reading
The full entry behind this definition.
- Color AccessibilityUI foundation
- ContrastUI foundation
- LightnessUI foundation
Nearby in the Atlas
Adjacent territory, found through shared tags rather than a stated link.