WCAG 2.0 requires a contrast of 7:1 to reach AAA levels. [1]
you can test it yourself with a bunch of tools but I couldn't find link to results on any of them [2][3][4].
[1] http://www.w3.org/WAI/WCAG20/quickref/#qr-visual-audio-contr...
[2] http://webaim.org/resources/contrastchecker/
[3] http://snook.ca/technical/colour_contrast/colour.html
[4] http://contrastchecker.com/