WCAG Contrast Checker: Make Sure Your Colours Pass Accessibility

A design can look beautiful and still fail readers with low vision if the text and background colours don't contrast enough. A Contrast Checker tells you instantly whether your colour combination passes accessibility standards — before real users run into the problem.

What Is a WCAG Contrast Checker?

A WCAG Contrast Checker calculates the contrast ratio between a foreground colour (usually text) and a background colour, then compares that ratio against the official Web Content Accessibility Guidelines (WCAG) thresholds, telling you whether the combination passes at AA or AAA level for normal and large text.

Who Needs This Tool?

Accessible colour contrast matters for every public-facing design:

• Web designers verifying text-on-background combinations before finalising a design system
• Developers double-checking button and link colours meet accessibility requirements
• Agencies ensuring client websites meet WCAG compliance for legal or contractual reasons
• UX designers comparing several colour options to find one that's both on-brand and accessible
• Government and public sector teams meeting mandatory accessibility standards
• Anyone designing with branded colours that happen to be close in lightness to their background

How to Use the WCAG Contrast Checker on Next Web Tools

1. Open the Contrast Checker tool.
2. Enter your foreground (text) colour and background colour, either by HEX code or visual picker.
3. View the calculated contrast ratio and whether it passes WCAG AA and AAA levels.
4. Adjust either colour until the combination passes the level you need.

If a combination fails, try adjusting the lightness of one colour slightly using our Colour Picker's HSL view rather than changing the hue entirely — small lightness shifts are often enough to pass without abandoning your brand colour.

Tips for Better Results

• Large text (typically 18pt+/24px or bold 14pt+) has a lower contrast requirement than normal body text under WCAG guidelines.
• AAA is a stricter standard than AA — aim for AA as a minimum baseline, and AAA where practical for critical content.
• Don't rely on colour alone to convey meaning (like error states) — pair it with icons or text labels for users with colour vision deficiencies.
• Re-check contrast any time you adjust your brand palette, since even small colour tweaks can shift a combination from passing to failing.

Contrast Checker vs Eyeballing It

A colour combination can look perfectly readable to someone with typical vision while still failing accessibility guidelines for users with low vision or colour vision deficiencies. Contrast ratio is a precise mathematical calculation, not a subjective impression — which is exactly why a checker is necessary rather than just trusting your own eyes, even if you have a good design sense.

Frequently Asked Questions

What contrast ratio do I need to pass WCAG AA?

Normal text needs at least a 4.5:1 ratio, while large text needs at least 3:1 to pass the AA standard.

What's the difference between AA and AAA?

AAA is a stricter standard, requiring at least 7:1 for normal text and 4.5:1 for large text, intended for content where maximum accessibility is especially important.

Does this apply to background images, not just solid colours?

Yes in principle, though checking contrast against a busy background image is harder to calculate precisely — solid colour backgrounds are far easier to verify reliably.

Is WCAG compliance legally required?

Requirements vary by country and sector, but many public sector and larger commercial websites are legally required to meet WCAG AA as a baseline.

Final Thoughts

Accessible contrast is one of the easiest accessibility wins to implement, and a checker makes it a thirty-second step rather than a guess. Once your text passes, finish your design system with our Gradient Generator and Box Shadow Generator, checking contrast again any time text sits on top of either effect.