Text must have a contrast ratio of at least 4.5:1 against its background color. This makes content easier for everyone to read, but especially partially sighted people.
Accessibility Requirements for 1.4.3 Contrast Minimum (AA)
- Text (whether plain text or in an image) has a contrast ratio of at least 4.5:1 against its background color.
Common mistakes for 1.4.3 Contrast Minimum (AA)
- Text does not have a contrast ratio of at least 4.5:1 against its background color.
Techniques for 1.4.3 Contrast Minimum (AA)
Common Failures for 1.4.3 Contrast Minimum (AA)
The following are common mistakes that are considered failures of Success Criterion 1.4.3 by the WCAG Working Group.
- F24: Failure of Success Criterion 1.4.3, 1.4.6 and 1.4.8 due to specifying foreground colors without specifying background colors or vice versa
- F83: Failure of Success Criterion 1.4.3 and 1.4.6 due to using background images that do not provide sufficient contrast with foreground text (or images of text)
FAQs about Contrast Minimum
What is the best color contrast ratio?
4.5:1 When it comes to color contrast, the guidelines state that text and images of text must have a contrast ratio of at least 4.5:1
Is a higher contrast ratio better?
A monitor’s contrast ratio indicates the depth of blacks – a higher contrast ratio means deeper blacks – and by extension, better picture quality. It’s a very important part of picture quality, so if you want something that looks good (particularly in a dark room), be sure to get a monitor that has good contrast.
What colors are not ADA compliant?
There are three main types of color deficiencies to consider: red/green, blue/yellow, and complete color blindness.
Why is contrast so important?
Contrast helps organize your design and establish a hierarchy—which simply shows which parts of your design are most important (and signals viewers to focus on those). But more than emphasizing the focal point of your design, good use of contrast adds visual interest.
What is the most difficult color combination to read?
Most designers know that blue and red are the worst color combinations possible when it comes to text, and especially blue text on a red background. The colors are both too strong and fight to overpower each other, which plays tricks with our eyes.