On 9-29-2016 we made the following adjustments to the date ranges of Gen x, Millenials, Gen Z: 1  Changed Gen X last births date from 1981 to 1979. 2  Changed Millennial start birth date from 1975 to 1980. 3  Changed Gen Z start birth date from 1995 to 1996.  Changed Gen Z last births date from 2015 to 2010.