How many possible minecraft usernames are there? There are:; 14436162848876302857680359974107136000 POSSIBLE USERNAMES; or, 14 UNDECILLION POSSIBLE USERNAMES. EACH PERSON WOULD HAVE TO HAVE ABOUT 1.7 OCTILLION ACCOUNTS TO TAKE EVERY SINGLE ONE. This is because there are 53 possible characters in a username. (ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxys_)