Color Contrast Checker: Pass WCAG Every Time

Contrast issues are one of the fastest ways to fail accessibility checks. A color contrast checker helps you verify that text remains readable for everyone, including users with low vision or color blindness.

This guide shows how contrast ratios work and how to fix common design mistakes.

What is a contrast ratio?

Contrast ratio measures the difference between two colors, usually text and background. The higher the ratio, the easier it is to read. WCAG standards define minimum ratios:

• AA normal text: 4.5:1
• AA large text: 3:1
• AAA normal text: 7:1

When to check contrast

• Designing buttons and CTAs
• Building dark mode and light mode themes
• Creating charts and data visualizations
• Auditing existing pages for accessibility

Fast workflow

1. Pick a foreground color.
2. Pick a background color.
3. Review the ratio and pass/fail status.
4. Adjust the colors until AA or AAA is achieved.

Common contrast mistakes

• Light gray text on white backgrounds.
• Thin fonts that reduce legibility.
• Accent colors with low luminance for body copy.
• Gradients where parts of the text fall below 4.5:1.

Practical fixes

• Darken the text color by 10 to 20 percent.
• Use a darker background behind key text.
• Increase font size or weight when contrast is borderline.
• Avoid light text on busy gradients.

Accessibility checklist

• Primary text meets 4.5:1
• Large headlines meet 3:1
• Buttons and CTA text pass AA
• Hover states keep contrast consistent

FAQ

Does large text have different rules? Yes. Large text has a lower requirement at 3:1 for AA.

What about icons? Icons should meet similar contrast rules if they communicate meaning.

Can I use brand colors and still pass? Usually yes. Slightly adjust the brightness to meet the ratio while preserving brand hue.

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