The purpose of this study was to propose a computer-based grading method for men's formal wear according to the sizing systems based on the size and dimension whereby manufactured men's formal wear can be classified. The following procedures were as follows : 1) We surveyed the sizing systems and the computer-grading methods that have been used and presently practiced by the domestic garment industry of the ready-made men's wear. 2) Using the survey data of the domestic men's ready-made clothing industry and that of the National Anthropometric Survey of Korea in 1997, we proposed the new sizing and grading systems of men's formal wear within the framework of the Korean Garment Industry's directions and the data of the domestic men's ready-made clothing industry. 3) The suitability of the new grading systems to the domestic garment industry were put to a wearing teat. The findings were as follows : 1) Survey of the domestic ready-made garment industry showed that each company classified its own manufactured goods according to its own sizing and grading systems. 2) The superiority of the grading system was been demonstrated by a high approval rate of the subjects who participated in the testing.