Hi, the staunton style is the official type of piece used by the FIDE. there is a scale from 1 to 6 for the size. The height of rook has to be the same size than a square, this is how we check if a board is regular with the pieces. Ask to the Federation Internationale Des Echecs (FIDE in french), they will answer you. For the conversion in centimeters read the french page.
There is the link in english on wikipedia :
http://en.wikipedia.org/wiki/Chess_piece
Good Luck.
I've been searching the internet for the dimensions of the Staunton chessmen lately, but alas, no results.
I'd like to give turning my own pieces a go over the winter, but I don't know a whole lot about how you're supposed to go about this project.
Thus I turn to you, the good people of chess cow: Do you happen to know how/where to aqquire these dimensions?