Last updated: March 2026
Frequently Asked Questions
Why do accessible color pairs matter?
Roughly 8% of men and 0.5% of women have some form of color vision deficiency, and everyone's contrast sensitivity declines with age. Accessible pairs ensure your text is readable by as many users as possible — and they're often required by law (ADA in the US, EAA in the EU).
Does this work with transparent or semi-transparent colors?
No, contrast ratios require fully opaque colors because they're computed from the final rendered pixel color. For semi-transparent designs, composite the overlay with its background first, then check that result against the text color.
What's the difference between 4.5:1 and 7:1?
4.5:1 (AA) is the minimum for normal text to be legible for most users. 7:1 (AAA) is significantly higher contrast and remains readable for users with more advanced vision impairment or in bright sunlight. Aim for AAA on critical body text.
Do large headings need the same contrast?
WCAG allows a lower ratio for large text (18pt+ regular or 14pt+ bold): 3:1 for AA, 4.5:1 for AAA. This tool defaults to the strictest rule so results work in every context.