Abstract: In order to solve the problem that the current ready-to-wear size cannot provide personalized services for the group close to the mean size, this paper measures different groups with the same number via the normal distribution law as the measurements to explain a new method for determining the size of the clothes. First, determine the target population and sample their body measurements to obtain the sampling data, and then fit related corresponding normal distribution and normal distribution curve. According to the normal distribution, the target population is divided according to similar or equal numbers of people. And finally determine the clothing size according to the measurements corresponding to the groups, so as to adapt the size to the crowd distribution and optimize the size sequence to cover the target population.

Key words: normal distribution; clothing; size; number; measurements; cup