Color contrast

Color contrast is one of the most fundamental accessibility requirements. If text or controls don’t stand out enough from the background, they become unreadable in bright light, for users with low vision, or for those with color blindness.

WCAG (Web Content Accessibility Guidelines) defines minimum contrast ratios to ensure legibility and equal access. Meeting these standards improves usability for everyone, not just people with disabilities.

Guidelines for designing with accessible color contrast.

Meet WCAG minimum contrast ratios

• Normal text (below 18px / 1.125rem regular and 14px / 0.875rem bold): at least 4.5:1
• Large text (18px / 1.125rem + or 14px / 0.875rem bold): at least 3:1
• Non-text UI components and graphical objects: at least 3:1

References:

• WCAG 1.4.3: Contrast minimum
• Contrast checker – WebAIM

Test with real tools, not by eye

Use tools like WebAIM Contrast Checker, Stark, or Axe to ensure compliance. Human perception is unreliable.

Design for different states

Verify contrast for hover, focus, active, and disabled states. Disabled elements often fail contrast and become unreadable.

References:

• Button states: communicate interaction – Nielsen Norman Group

Avoid relying only on color for meaning

Contrast must be paired with other indicators (for example: icons, labels, underline for links). This ensures accessibility for users with color blindness.

References:

• WCAG 1.4.1: Use of color

Consider context and environment

Text that meets WCAG can still be hard to read in sunlight or on poor screens. When in doubt, aim above minimum contrast ratios.

References:

• ‍Inclusive design patterns – Heydon Pickering

Frequent mistakes when applying color contrast.

Using light gray text on white backgrounds

Often fails contrast requirements, especially in body text.

Ignoring non-text elements

Icons, focus outlines, and form borders must also meet contrast standards.

Not testing interactive states

Buttons and links may meet contrast only in default state but fail on hover or disabled states.

Relying only on brand colors without adjustment

Many brand palettes need adjustments for accessibility. Blindly following them harms usability.

Key takeaways for color contrast.

• Always meet WCAG minimum contrast ratios for text and UI elements.
• Test with tools, not by eye.
• Check contrast across all interactive states.
• Don’t rely only on color to convey meaning.
• When possible, exceed minimum ratios for better readability.

Accessible color contrast is not just a requirement, it’s the foundation of inclusive, usable design.