Question 1

How is contrast ratio calculated?

Accepted Answer

We use the WCAG formula: (L1 + 0.05) / (L2 + 0.05), where L1 and L2 are the relative luminances of the lighter and darker colors. The result is a ratio (e.g. 4.5:1 for AA normal text).

Question 2

What do AA and AAA mean?

Accepted Answer

AA is the minimum conformance level (4.5:1 for normal text, 3:1 for large text). AAA is enhanced (7:1 and 4.5:1). This tool checks both so you can aim for the level you need.

Question 3

Why do my URL parameters update when I change colors?

Accepted Answer

So you can share or bookmark a specific combination. Anyone opening the link will see the same colors and ratio.