Here's a piece from some site about katana if anyone's interested:
The length of the blade varied considerably during the course of its history. In the late 14th and early 15th centuries, katana blades tended to be between 70 to 73 cm (27.6 to 28.7 in) in length. While during the early 16th century, the average length was closer to 60 cm (23.6 in). By the late 16th century, the average length returned to approximately 73 cm (28.7 in).