A challenge for manufacturers of garments is to decide which sizes to make available for a potential target group. Mismatches between the garment’s sizes/proportions and a target group will decrease its fit and increase loss of sales. The purpose of this study is to develop a systematic model to identify and optimize the distribution of a garment’s sizes and proportions in order to provide a target group appropriate fit. This study is based on sample-garment measurements, experienced-based values and data containing body measurements of 2208 individuals. Statistical data from the case were analysed to find a model to detect mismatches between standard garments and a target group. The results show that it is possible to use a systematic model to define the shortcomings of a garment´s range of sizes and proportions. If implemented, this could have effects on the available garment sizes and its proportions, resulting an increased garment fit for a target group.