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Color Contrast Checker

Test color contrast for web accessibility. Check WCAG 2.0 compliance instantly.

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The quick brown fox jumps over the lazy dog

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About Color Contrast

Why Color Accessibility Matters

According to a meta-analysis published in PubMed, approximately 8% of men and 0.5% of women have red-green color deficiency worldwide, representing over 300 million people globally. Proper color contrast ensures your content is accessible to all users, including those with color vision deficiencies.

Color contrast is essential for web accessibility. Our contrast checker helps you ensure your text is readable against its background by testing against WCAG 2.0 standards.

What is WCAG?

WCAG (Web Content Accessibility Guidelines) is a set of recommendations for making web content more accessible. Color contrast ratios help ensure text is readable for people with visual impairments, including color blindness.

  • Level AA: Minimum contrast for most web content
  • Level AAA: Enhanced contrast for maximum accessibility
  • Normal Text: Text under 18pt (or 14pt bold)
  • Large Text: Text 18pt or larger (or 14pt bold or larger)

Contrast Ratio Requirements

Normal Text

  • AA Level: 4.5:1 minimum
  • AAA Level: 7:1 minimum
  • Applies to body text and small text
  • Most common requirement

Large Text (18pt+)

  • AA Level: 3:1 minimum
  • AAA Level: 4.5:1 minimum
  • Applies to headings and large text
  • Lower requirement due to size

Common Use Cases

Web Design

  • Testing website color schemes
  • Button and link accessibility
  • Navigation menu contrast
  • Form input legibility

Brand & Marketing

  • Logo color combinations
  • Marketing material readability
  • Presentation accessibility
  • Social media graphics

App Development

  • UI element visibility
  • Dark mode compatibility
  • Alert and error messages
  • Mobile app accessibility

Compliance

  • ADA compliance testing
  • Section 508 requirements
  • WCAG 2.0/2.1 validation
  • Accessibility audits

Why Contrast Matters

  • Accessibility: Makes content readable for users with visual impairments
  • Legal Compliance: Meets ADA and WCAG legal requirements
  • Better UX: Improves readability for all users in all conditions
  • Professional Quality: Shows attention to detail and inclusivity
  • SEO Benefits: Accessibility improvements can boost search rankings

Pro Tips

  • Aim for AA level as a minimum standard
  • Test your colors on actual devices and in different lighting
  • Use the swap button to test both light and dark themes
  • Consider users with color blindness - high contrast helps everyone
  • Document your color choices for design systems

Understanding Color Vision Deficiency

Types of Color Blindness

Color blindness affects how people perceive colors. The most common form is red-green color blindness, but other types exist.

  • Deuteranomaly: Reduced green sensitivity (most common)
  • Protanomaly: Reduced red sensitivity
  • Tritanomaly: Reduced blue sensitivity (rare)
  • Achromatopsia: Complete color blindness (very rare)

Impact on Design

Proper contrast ensures readability regardless of color perception. High contrast ratios work for everyone.

  • Don't rely solely on color to convey information
  • Use patterns, icons, or text labels as backups
  • High contrast benefits users with low vision
  • Test designs with color blindness simulators

How Contrast Ratios Are Calculated

The Mathematics Behind Contrast

Contrast ratios are calculated using the relative luminance of colors, not just their RGB values. The formula considers how the human eye perceives brightness differently across the color spectrum.

  • Relative luminance formula: L = 0.2126 × R + 0.7152 × G + 0.0722 × B
  • Human eyes are most sensitive to green light (71.52% weight)
  • Blue has the least impact on perceived brightness (7.22%)
  • Contrast ratio = (L1 + 0.05) / (L2 + 0.05) where L1 > L2
  • Values range from 1:1 (white on white) to 21:1 (black on white)

Accessibility Standards Evolution

WCAG Version History

Web Content Accessibility Guidelines have evolved to address modern web design needs while maintaining backward compatibility.

  • WCAG 1.0 (1999): First formal web accessibility guidelines
  • WCAG 2.0 (2008): Introduced contrast ratio requirements
  • WCAG 2.1 (2018): Added mobile and low vision enhancements
  • WCAG 2.2 (2023): Additional cognitive accessibility criteria
  • WCAG 3.0 (in development): Advanced perceptual contrast model

Legal Requirements Worldwide

United States
ADA (Americans with Disabilities Act) and Section 508 require accessible digital content for government and public websites.

  • Federal websites must meet WCAG 2.0 AA
  • Many states enforce accessibility laws
  • Private sector increasingly adopting standards

Europe & International
European Accessibility Act (EAA) and other international standards mandate digital accessibility.

  • EU: EN 301 549 standard (based on WCAG 2.1)
  • UK: Equality Act 2010
  • Canada: AODA (Accessibility for Ontarians)

Design Best Practices

Achieving High Contrast

Strategic color selection ensures readability while maintaining aesthetic appeal. Here are proven techniques for accessible color schemes.

  • Use dark text (#000000 to #333333) on light backgrounds (#FFFFFF to #F5F5F5)
  • Or light text (#FFFFFF to #F0F0F0) on dark backgrounds (#000000 to #222222)
  • Avoid pure black on pure white (can cause eye strain)
  • Use slightly off-white (#FAFAFA) and off-black (#1A1A1A)
  • Test colored text with the 4.5:1 ratio requirement
  • Increase font weight if contrast is borderline

Dark Mode Considerations

Dark mode requires careful contrast management. What works in light mode may fail in dark mode and vice versa.

  • Pure white on pure black creates eye strain (halation effect)
  • Use #E0E0E0 to #F0F0F0 text on #121212 to #1E1E1E backgrounds
  • Reduce saturation of colored text in dark mode
  • Test both themes separately for compliance
  • Consider user preference (auto dark mode)

Common Contrast Failures

Failed Combinations

  • Light gray text on white (#CCCCCC on #FFFFFF = 1.6:1)
  • Yellow text on white (#FFFF00 on #FFFFFF = 1.07:1)
  • Blue links on black (#0000FF on #000000 = 2.4:1)
  • Red on green (poor for colorblind users)

Passing Alternatives

  • Dark gray on white (#595959 on #FFFFFF = 7:1)
  • Dark yellow/gold on white (#AA8800 on #FFFFFF = 4.5:1)
  • Light blue on black (#5B9BD5 on #000000 = 7.2:1)
  • Use patterns/icons with color differences

Advanced Accessibility Techniques

Non-Text Contrast (WCAG 2.1)

WCAG 2.1 introduced requirements for non-text elements like UI components, graphics, and interactive elements.

  • UI components: 3:1 minimum contrast with adjacent colors
  • Form inputs: Clear visual boundary against background
  • Focus indicators: Must have 3:1 contrast ratio
  • Graphical objects: Icons and meaningful graphics need 3:1
  • Exception: Logos and decorative elements exempt

Testing Beyond Automated Tools

While automated contrast checkers are essential, comprehensive accessibility testing requires multiple approaches.

  • Test on real devices in various lighting conditions
  • Use browser DevTools accessibility audits
  • Simulate color blindness with browser extensions
  • Get feedback from users with disabilities
  • Test with screen readers (they announce color info)
  • Consider cognitive load and reading comprehension

Building Accessible Color Systems

Design systems should include pre-tested accessible color combinations to ensure consistency across products.

  • Document passing combinations for developers
  • Create semantic color tokens (primary, secondary, error, success)
  • Include both light and dark mode variants
  • Provide contrast ratios in design documentation
  • Use automated testing in CI/CD pipelines
  • Regular audits as brand colors evolve

Frequently Asked Questions

What is WCAG and why does it matter?

WCAG (Web Content Accessibility Guidelines) ensures websites are accessible to everyone, including people with visual impairments. Meeting WCAG standards is often legally required.

What contrast ratio do I need for accessibility?

For normal text, aim for 4.5:1 (AA level) or 7:1 (AAA level). For large text (18pt+), 3:1 (AA) or 4.5:1 (AAA) is acceptable. Our checker shows compliance for all levels.

Why does my color combination fail WCAG?

Colors with insufficient contrast make text hard to read, especially for people with low vision or color blindness. Adjust lightness/darkness to increase contrast ratio.

Can I test dark mode colors?

Yes! Use our swap button to quickly test both light and dark color schemes. Ensure both meet accessibility standards for your website or app.

What happens if I don't meet WCAG standards?

Non-compliant sites may face legal issues, lose users with accessibility needs, and have poorer SEO. Good contrast benefits all users, not just those with visual impairments.