I got an 8, not bad for an old fart.

As an eye doctor I can tell you that this type of test is normally pretty accurate, but it could vary a lot depending on your monitor. Usually it is administered using actual color chips and must be done under a special "daylight" light source. 3% of men have some degree of genetic color deficiency, only 1 in 3,000 women are affected. Age, cataracts, macular degeneration, and other eye diseases can cause acquired color vision loss later in life. Any change in color perception should be evaluated by an eye doctor.