This pair is under 4.5:1, so the labels and buttons on this page switched to black or white to stay readable. The big Aa and the sample below still show the real pair.
Built to be read by everyone
Body copy at 16px. Most paragraphs, form labels, links and navigation sit at this size, so it needs 4.5:1 to meet ADA.
Caption and legal text at 12px
About this tool
What it is
A contrast checker for one text color on one background, or for a whole palette at once. It tests against WCAG 2.1, the standard the ADA points to.
What it does
Shows whether a pair is safe for body text, large text or UI, previews it as real type, and suggests the closest passing shade. Compare entire palette tests every color against every other, both ways, and exports the grid or the approved pairings.
Why it matters
Low contrast is the web's most common accessibility failure. It shuts out people with low vision or color blindness, and it's a legal risk, with thousands of ADA website lawsuits a year. Fixing it at the brand stage is cheapest.
ADA & WCAG contrast rules
Which standard ADA points to
The ADA itself has no numeric rule. The DOJ's 2024 Title II rule adopts WCAG 2.1 Level AA, and courts and settlements commonly hold private businesses to the same bar under Title III. WCAG 2.2 keeps the same contrast numbers, so AA here covers both.
The thresholds
- 1.4.3 AA: 4.5:1 for body text, 3:1 for large text
- 1.4.6 AAA: 7:1 body, 4.5:1 large
- 1.4.11 AA: 3:1 for icons, input borders, focus rings and chart marks against what's next to them
What counts as large text
At least 18pt (24px) regular, or 14pt (18.66px) bold. Pairs marked Aa* are only safe at these sizes: headlines, hero text, big buttons.
No rounding up
A pair at 4.49:1 fails AA. This tool truncates ratios to two decimals and tests the unrounded value, so a displayed 4.50 always means a real pass.
Exempt
- Logos and brand wordmarks
- Disabled controls
- Purely decorative text, or text inside photos that isn't meaningful
What this tool can't tell you
Passing contrast is one part of accessibility, not all of it. A site also needs keyboard access, text alternatives, captions and more to meet WCAG AA. This tool checks solid colors only, so for text over photos, gradients or see-through layers, sample the lightest and darkest spots behind the text and test both. This is not legal advice.
The math
Ratio = (L1 + 0.05) / (L2 + 0.05), where L is relative luminance from linearized sRGB: 0.2126 R + 0.7152 G + 0.0722 B. APCA (proposed for WCAG 3) is still a draft and not a legal standard.