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Accessibility at the UW

Color Contrast: Why It Matters for Web Accessibility

Post categories: Web Accessibility

This post kicks off a November series on digital accessibility barriers in websites and how to fix them. Each week, we’ll explore a common issue that can make a website harder to use for people with disabilities and share practical ways to create more inclusive digital experiences.

Color can be a powerful element of design. It can create mood, highlight key information, and guide users’ attention. But when color is used without enough contrast—or as the only way to convey information—it can become a serious accessibility barrier.

What Is Color Contrast?

Color contrast refers to the difference in brightness between two colors—typically between text and its background, or between different visual elements. Good contrast ensures that people with low vision, color blindness, or other visual impairments can read and interact with your content.
For example, light gray text on a white background or blue text on a red background can be nearly unreadable for many users. Even people without diagnosed vision conditions may struggle when viewing low-contrast content on mobile devices or in bright light.

Why It Matters

When color is the only cue used to convey information, users who can’t perceive those color differences may miss important details altogether. Someone who is blind won’t know that “errors are in red.” Someone with color blindness may not be able to distinguish a red line from a green one in a chart.

Low contrast or color-only cues can affect:

  • Text readability (e.g., poor contrast between text and background)
  • User interface elements (e.g., faint button borders or input fields)
  • Charts and graphics (e.g., multiple data lines distinguished only by color)

Inaccessible color use can make websites confusing, inconsistent, or completely unusable for a portion of your audience.

Quick Color Contrast Checks

  1. Include Text with Color Indicators
    If you’re using colors like red, yellow, or green to show status (e.g., progress or alerts), always include clear text labels. For example:

    • Green check “On track”
    • Yellow alert sign “At risk”
    • Red x mark “Off track”
  2. Check Font Color Contrast
    Using a new font color? Use a tool like WebAIM Color Contrast Checker to quickly test readability.
  3. Make Chart and Graph Clear
    Add patterns and labels when you’re using color. For example:  
    • Label pie charts sections
    • Use patterns (like dotted or dashed lines) to differentiate lines and bars

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