The best estimate is that Karloff in full costume was between 6'2 - 6'4, given that the heavy boots added @ 4 and the head piece another 1 to Karloff's 5'10 - 5'11 frame [Karloff is listed as 5'10 in some bios and 5'11 in others]. In Shelley's novel, the Frankenstein monster was 8 feet tall.