year episode "I Robot, You  Jane", Malcolm brings up Buffys school records on his computer. In  the first view, we see that Buffy was born on 24 October 1980, and  that she is a sophomore. The second time we see Buffys records, her  birthday is 6 May 1979, and she is a senior. Joss Whedon (qv)  finally decreed Buffys birthday to be 19 January 1981.