Quick reference
Common questions answered concisely, plus a cheat sheet of accessible colour pairings.
Frequently asked questions
What's the difference between AA and AAA?
AA requires a minimum contrast ratio of 4.5:1 for regular text and 3:1 for large text. AAA requires 7:1 for regular text and 4.5:1 for large text. AA is the standard most organisations target. AAA is a higher bar recommended for critical content and body text.
What counts as large text?
Large text is 18pt (24px) or above at normal weight, or 14pt (approximately 18.66px) or above if bold. Large text has a lower contrast requirement because its size already makes it more legible.
Why do my brand colours fail?
Many brand palettes were designed for visual impact rather than accessibility. Vibrant colours often have similar lightness values, which means low contrast. The good news: our improvement suggestions can find close alternatives that preserve your brand's character while meeting accessibility standards.
Can I use colour alone to convey information?
No. WCAG Success Criterion 1.4.1 states that colour must not be the only visual means of conveying information. Always pair colour with text labels, icons, patterns, or underlines. For example, don't just make error text red — also add an error icon and a descriptive message.
What contrast ratio should I aim for?
As a rule of thumb: aim for at least 7:1 for body text and important content. This meets AAA and provides comfortable readability for the widest range of users. For large headings and decorative text, 4.5:1 is usually sufficient.
Does this tool check for colour blindness?
Not yet. Our colour blind simulation mode is coming soon and will show how your palette appears under different types of colour vision deficiency. In the meantime, read our guide to colour blindness for practical design tips.
Accessible colour pairings cheat sheet
Starting points for designers. All pairings below meet WCAG AA for regular text (4.5:1+). Ratios shown are approximate.
Black on White
21:1
White on Dark Navy
16.5:1
Dark Green on Light Mint
9.4:1
Dark Blue on Light Grey
9.8:1
Purple on Lavender
8.2:1
Dark Amber on Cream
8.7:1
White on Blue
9:1
White on Dark Red
7.8:1
Threshold quick reference
| Ratio | AA | AAA |
|---|---|---|
| Below 3:1 | Fail all | Fail all |
| 3:1 – 4.49:1 | Pass large only | Fail all |
| 4.5:1 – 6.99:1 | Pass all | Pass large only |
| 7:1+ | Pass all | Pass all |