Color Contrast Checker

The Color Contrast Checker helps designers, developers, and accessibility professionals ensure that color combinations meet WCAG 2.x accessibility standards. Proper contrast between text and background colors is essential for readability, especially for users with low vision or color vision deficiencies.

What is Color Contrast Ratio?

Color contrast ratio measures the difference in perceived luminance (brightness) between two colors. It ranges from 1:1 (identical colors, no contrast) to 21:1 (maximum contrast: black on white). The ratio is calculated using the WCAG 2.x formula based on relative luminance values of both colors.

WCAG Contrast Requirements

The Web Content Accessibility Guidelines (WCAG) define two conformance levels for color contrast:

What counts as "large text"?

WCAG defines large text as at least 18 point (24px) regular weight, or at least 14 point (18.66px) bold weight. Large text has lower contrast requirements because larger characters are naturally easier to read.

How to Use This Tool

1. Enter your colors: Pick foreground (text) and background colors using the color pickers, type hex codes, or click a preset example.
2. Check the live preview: See how your colors look on real UI elements (headings, body text, buttons, links, form inputs) instantly.
3. Click "Check Contrast": Get the exact contrast ratio and WCAG compliance status for normal text, large text, and UI components.
4. Apply suggestions: If your colors fail, use the automatic suggestions to find the closest accessible alternative.

Understanding the Results

Contrast Ratio

The main number (e.g., 8.59:1) tells you how different the two colors appear. Higher is better for readability. A ratio of at least 4.5:1 ensures most users can comfortably read normal-sized text.

Overall Grade

• AAA (Excellent): Passes all WCAG criteria including enhanced (7:1+). Best possible accessibility.
• AA (Good): Passes standard requirements (4.5:1+). Meets legal requirements in most jurisdictions.
• AA Large (Partial): Only passes for large text or UI components (3:1+). Normal text fails.
• Fail (Poor): Does not meet any WCAG contrast criteria. Text will be difficult to read for many users.

Color Suggestions

When your colors do not meet contrast requirements, the tool suggests the nearest accessible color by adjusting lightness while preserving hue and saturation. You can apply suggestions with a single click.

Why Color Contrast Matters

• Legal compliance: Many countries require WCAG AA conformance by law (ADA, Section 508, EN 301 549, EAA).
• User experience: Good contrast improves readability for all users, not just those with disabilities.
• SEO impact: Search engines increasingly factor accessibility into rankings.
• Audience reach: Approximately 1 in 12 men and 1 in 200 women have color vision deficiency.

Tips for Choosing Accessible Colors

• Start with sufficient contrast, then refine the design — it is harder to fix contrast retroactively.
• Avoid placing colored text on colored backgrounds without testing. Even colors that "look different" may fail contrast checks.
• Light gray text on white backgrounds is one of the most common accessibility failures.
• Use this tool during design, not just during auditing — catching issues early saves significant rework.
• Do not rely on color alone to convey information; use shapes, patterns, or labels as well.

Frequently Asked Questions

What is color contrast ratio?

Color contrast ratio measures the difference in perceived luminance between two colors. It ranges from 1:1 (no contrast, same color) to 21:1 (maximum contrast, black on white). The ratio is calculated using the WCAG 2.x formula: (L1 + 0.05) / (L2 + 0.05), where L1 is the lighter color's relative luminance and L2 is the darker color's.

What contrast ratio is required for WCAG AA compliance?

WCAG AA requires a minimum contrast ratio of 4.5:1 for normal text (under 18pt or 14pt bold) and 3:1 for large text (18pt+ or 14pt+ bold). For non-text UI components and graphical objects, the minimum is 3:1.

What is the difference between WCAG AA and AAA?

WCAG AA is the standard compliance level requiring 4.5:1 for normal text and 3:1 for large text. WCAG AAA is the enhanced level requiring 7:1 for normal text and 4.5:1 for large text. AA is required by most accessibility laws, while AAA is recommended but not typically required for entire websites.

What is considered large text in WCAG guidelines?

In WCAG guidelines, large text is defined as text that is at least 18 point (24px) regular weight, or at least 14 point (approximately 18.66px) bold weight. Large text has lower contrast requirements because larger characters are easier to read.

How do I fix low color contrast?

To fix low color contrast: (1) Darken the text color or lighten the background, or vice versa. (2) Use our color suggestion feature which automatically finds the nearest color that passes. (3) Increase the font size to qualify as "large text" which has lower requirements. (4) Avoid using color alone to convey information.

Does color contrast only apply to text?

No. WCAG 2.1 Success Criterion 1.4.11 requires a minimum 3:1 contrast ratio for non-text elements including form input borders, icons, and graphical objects essential for understanding content. This applies to UI components like buttons, form fields, and focus indicators.

Additional Resources

• WCAG 2.1: Understanding Contrast (Minimum)
• WCAG 2.1: Understanding Contrast (Enhanced)
• Web Content Accessibility Guidelines - Wikipedia