When creating digital content such as electronic documents, there must be sufficient color contrast of text and images of text. This ensures content is readable and usable by all individuals, including those with visual impairments. As a designer, developer, or content creator, it is important to choose appropriate foreground and background colors for text. While there are many pitfalls for poor color contrast, the information below explores the importance of color contrast, guidelines for meeting accessibility requirements, and methods to test color contrast in electronic documents and images.

Importance of Sufficient Color Contrast

Color contrast refers to the difference in luminance or color between text or images of text and its background. Sufficient color contrast is essential for accessibility and readability, especially for individuals with low vision or color deficiencies. The Web Content Accessibility Guidelines for 1.4.3 Contrast (minimum) defines specific contrast ratios to ensure text is readable against its background. The minimum contrast ratio for text or images of text that are less than 18 point or 14 point bold fonts against its background is 4.5:1 except for the following:

• Large-scale text and images of large-scale text, which is text that is higher than 14 point bold or 18 point fonts, and have a contrast ratio of at least 3:1.
• Text or images of text that are part of an inactive user interface component, that are pure decoration, that are not visible to anyone, or that are part of a picture that contains significant other visual content.
• Text that is part of a logo or brand name.

Note: The maximum ratio on the color contrast scale occurs between black text and a white background (or vice versa) at 15:1.

When creating content, it is important to choose your background and foreground colors in alignment with accessibility requirements. Two best practices are:

1. Choose high-contrast color combinations. Use dark text on a light background and vice versa.
2. Avoid color combinations that are difficult to differentiate, specifically red-green combinations that pose challenges for individuals with color blindness. Use alternative color combinations for clarity.

While tools are helpful, there are several best practices for using color contrast testing tools:

1. Ensure accuracy and thoroughness by testing different sections of your document, including headers, body text, and any images with text.
2. If your document will be viewed online or converted to PDF or other formats, test color contrast in those contexts as well.
3. Incorporate color contrast checks into your document review process to maintain digital accessibility standards consistently and regularly.
4. Create and use standard templates and color themes that meet color contrast requirements.

Methods for Testing Color Contrast

There are various methods for testing color contrast including manual contrast checking, built-in automated tools, and software and desktop-based applications. There are many tools available to perform the following:

Manual Contrast Checkers

• Silktide Accessibility Toolbar: Includes a contrast checker with an eyedropper tool for WCAG compliance testing.
• WebAIM Contrast Checker: Browser-based tool with a color picker for testing text/background contrast.
• Colour Contrast Analyzer (CCA): Free tool for Windows and macOS.

Built-in Tools in Design Software

Many content creation authoring and content creation tools, such as Adobe and Microsoft Office products, have built-in Accessibility Checkers that will flag a color contrast error or post a warning where additional manual testing may be needed. These automated checkers cannot test images of text; manual testing should always be performed.

Read more on how to access Accessibility Checkers at Accessibility Testing for Electronic Documents.

User Testing and Feedback

To gather feedback on color contrast accessibility and user experience, a creator can utilize end-user feedback and real-world testing by engaging users with visual impairments or diverse abilities in usability testing. While this should not be the primary method of testing color contrast, this may provide valuable feedback on your digital content, templates, and themes used to ensure your content is easy to read and understand by everyone.

Many other tools for testing color contrast can be found through a web search to meet your specific ICT product testing need, such as mobile applications. Please also see Section508.gov’s Create and Design and Develop pages for further information.