Purpose – The purpose of this paper is to develop a method for defining and categorizing upper lateral somatotypes for clothing size systems used for clothing pattern creation based on directional angles of 3D space vectors. Design/methodology/approach – 3D data for 317 men in their twenties obtained from the fifth Size Korea survey were used in this study. Standard landmarks and surfaces were set on the 3D shapes, and six space vector angles of the lateral form were defined and measured. Relationships among the measurement results were clarified, and the results were compared with those obtained using existing classifying methods. Findings – The measurement of the defined directional angles indicated that the swayback type and bend-forward type had the two extreme values, and the straight type was between the two values. The analysis of the correlation between six directional angles indicated that some points in the lower area of the upper body had a high correlation with other points in the lower area. Researchlimitations/implications – The subjects of this study were limited to lateral somatotypes, and there is a need for future studies that focus on frontal somatotypes. This research is confined to the upper lateral somatotypes of men in their twenties. Further study is needed to extend the results of this study to other body types such as those of elderly and overweight persons. Practical implications – Major angle measurements quantified by the somatotypes can be specifically reflect in developing and revised to the right patterns which is spread body shell replica or individual pattern for MTM. Social implications – This objective somatotype analysis method can be involved in determining individual body somatotype of ordermade clothes or can provided the accurate information interactively to MTM automatic customized pattern making system. Originality/value – Accurate measurements of size, shape, and posture were applied and characterized to realize the process. Accuracy was improved compared to existing 2D analysis methods through three-dimensional analysis using directional space vector angles based on 3D forms.