Selecting an appropriate bra product has long been a challenge for adolescent girls, whose breasts are rapidly growing. This challenge arises due to the absence of a rational benchmark for breast measurement. Traditional benchmarks are based on ergonomic principles, using reference points located on the human skeleton. However, the breast lacks a bone structure for support, leading to highly variable measurement results. In this study, the jugular notch and the xiphoid process were selected as breast measurement points according to academic principles. Their accuracy, stability, and deviation were experimentally investigated through tactile assessment of adolescent girls at different stages of development. Based on the experimental results, a novel breast measurement coordinate system was established, and its accuracy was verified by conversion calculations using a geodetic coordinate system. The results indicated that the numerical calculation of the breast shape was more accurate using the newly established breast measurement coordinate system.