Color contrast is a major accessibility issue on a web page. The greater the amount of contrast, the better the readability is for a page. The most contrast you can get is black text on a white background. Things go downhill from there. The degree of readability loss with colors other than black and white can be determined by a mathematical formula.
Three of the best tools for checking color contrast are:
- Juicy Studio has an online color contrast checker. For Firefox users, Juicy Studio has created a Firefox add-on for color contrast checking, too.
- The Accessibility Tools Framework (ACTF) provides a downloadable tool called aDesigner. There’s plenty of online help for you once you get the tool installed on your system.
- Web Accessibility Tools Consortium (WAT-C) has a range of Color Contrast Analyzers for various platforms.
Each of the tools will report back to you with a score for your page’s contrast. If your colors don’t have enough contrast for readability, you’ll get the bad news quickly with one of these tools.
I helped build a mobile friendly contrast checker at http://www.contrastchecker.com.
Peter, I usually automatically trash comments like this containing a link, but I looked at your contrast checker and it is very nice and quite simple. A good resource.