Success Criteria 1.4.3 Contrast (Minimum): The visual presentation of text and images of text has a contrast ratio of at least 4.5:1, except for the following:
- Large Text: Large-scale text and images of large-scale text have a contrast ratio of at least 3:1.
- Incidental: 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 other significant visual content have no contrast requirement.
- Logotypes: Text that is part of a logo or brand name has no minimum contrast requirement.
SC 1.4.3 Contrast (Minimum) supports the principle of Perceivable because people who have limited vision may have trouble reading text if there is not enough contrast between the text and the background. This SC is unique because it often applies to large groups of people who would not normally be considered individuals requiring accessibility considerations. Failure to meet this SC impacts people who are without perception of color, or who have limited vision, but it has no impact on someone who is without vision.
SC 1.4.3 encourages authors to present text with a minimum of 4.5:1 contrast with the background. Larger and wider text is easier to read, so the contrast requirements are a little less stringent (3:1). Users are not expected to rely on magnification to provide contrast clarity.
This does not apply to text which is:
- An inactive interface element, e.g., a disabled Submit button
- Decorative
- Part of a picture containing significant other details (such as graphs, diagrams, and screenshots)
- Part of a logo or branding
- Intended to be invisible to all users
- Changed to indicate it is a “visited” link
Impact of Nonconformance with SC 1.4.3 Contrast (Minimum)
| Type of Disability | Description of Impact |
|---|---|
| 302.2 With Limited Vision | Users with limited vision may have widely different visual perception. Individuals with limited vision may or may not use assistive technologies. Therefore, in addition to textual and programmatic cues necessary for assistive technologies, ICT must also present content consistently and predictably. Users who view content with magnifiers may not pick up alerts, warnings, or other content if such content is presented outside of a consistent and predictable navigation pattern or if the content is not itself viewable at large magnification. Content that becomes distorted when magnified can also prevent some users with limited vision from being able to understand or interact with the content. |
| 302.3 Without Perception of Color | Some users may not be able to perceive differences between certain colors, and therefore do not receive information conveyed by the colors (e.g., using gradients of color between red, yellow, and green to indicate an item’s status from poor to good). In such cases, ICT must provide additional information by alternative means that conveys the same meaning (e.g., shapes and/or textual labels in addition to the color). |
Applicability of Success Criteria 1.4.3 Contrast (Minimum)
| Technology | Applicability of SC 1.4.3 |
|---|---|
| Web | Applies directly; web developers must be aware of how various styles, whether applied independently or in conjunction with others, will affect the contrast between foreground text and backgrounds. In every style combination, the contrast must conform as described in SC 1.4.3. When including images that contain text, developers should ensure the text and its background provide sufficient contrast. |
| Software | Applies directly; when defining color properties for content and controls, software developers must ensure that all text and backgrounds provide sufficient contrast. |
| Office documents | Applies directly; content authors can directly set or modify text foreground and background using RGB values. Authors should also be aware that many of the built-in Office themes (defining default fonts, styles, and colors for text and various objects) may not conform to the minimum contrast requirement defined in SC 1.4.3. |
| PDF documents | Applies directly; while it is typically easier to modify text foreground and background colors to get sufficient contrast in source content, it is also possible with some PDF editors to directly modify color properties for text and other document objects. |
| Mobile Native | Applies directly; when defining color properties for content and controls, mobile-native software developers must ensure that all text and backgrounds provide sufficient contrast. |