Useful Free Web Tools For W3C Contrast Compliance

Here are a couple of very useful web based tools for checking W3C compliance.

The first by Johnathan Snook enables you to check the colour contrasts of your theme for W3C compliance when viewed by someone having color deficits or when viewed on a black and white screen. The tool will indicate that the colours pass the test if both the colour difference and the brightness difference exceed their threshold. It will indicate that it sort of passes if only one of the two values exceed their threshold. And finally, it'll fail to pass if neither value exceeds its threshold.

The tool will also indicate if the colours pass the newer WCAG 2.0 contrast ratio formula. The WCAG 2.0 formula differentiates between text smaller than 18pt text larger than 18pt (or text that is bold and larger than 14pt). For AA compliance, text should have a ratio of at least 4.5:1 (larger text, at least 3:1). For AAA compliance, text should have a ratio of at least 7:1 (larger text, at least 4.5:1).

The second by Juicy Studio enables you to check your CSS for validity against the W3C's validation service, along with a colour contrast test, and a test to ensure that relevant sizes are specified in relative units of measurement.