Contrast-Finder finds correct color contrasts for web accessibility
WCAG success criteria 1.4.3 requires text to have a minimum contrast ratio of 4.5 (and 3 for large text).
Contrast-Finder is a tool which computes the contrast between two colors (background, foreground) and checks if the contrast is valid. When the contrast is not valid, the main target is to suggest some correct colors contrasts.
Contrast-Finder is designed to be used by webdesigners, web developers or web accessibility professionals to improve the readability of HTML pages and websites.
The Contrast-Finder interface is a form with five mandatory fields.
This is the color of the text. You can fill in this field with color keyword, an hexadecimal value, or an RGB value. The input value is then previewed on the right of the field.
Authorised values are those listed in CSS color keywords (from CSS level 1 to CSS level 4).
#AABBCC. Please note that
#ABC works also, we automatically complete the field with
#AABBCC. You can also use this field without the
# character, so
FFFFFF works perfectly.
You can also use a short syntax like
255,255,255, which be interpreted as
This is the color of the background.
This field works just like the text color field.
Three possible values 3, 4.5 and 7.
How to choose a ratio? It depends on the following elements:
Two elements (size and bold) gives four combinations:
24px: ratio = 4.5
24px: ratio = 3
19px: ratio = 4.5
19px: ratio = 3
For level AAA the logic is the same, only the ratio increases in the the following way:
19pxcriteria can be understood as equivalent of
24pxcriteria can be understood as equivalent of
For a full and exhaustive understanding of how to interpret text size, one should read the defintion of large-scale text from WCAG.
It is either the text or background color. Default is text color.
The color you choose will be modified until we find a valid color. The other color won't change.
This is the default algorithm. It offers color options really close to the initial color. (Color distance is computed on on a mathematical basis, which may vary from a designer point of view.)
For some color combinations, the algorithm may not give any result ; in such a case, use the other algorithm.
This is the backup algorithm, in case the first one gives no result. Nevertheless, color options may be (strongly) different from the initial color.
If you have any problems with or questions about Contrast-Finder, please contact us:
All contributions are warmly welcome ! Translation, correction, bug report, new feature…
Feel free to play with source code, or discuss in the forum.