These size charts are based on body measurements. Non-stretch garments include 3-5cm breathing room. For example: if your bust and waist match an Unshirred size M, the final measurents of the garment will be 92 to 94cm bust and 68 to 70cm waist. Garments made of stretch fabrics include at least a natural stretch of 2-3cm. Shirred pieces will have elastic and/or lacing in the bodice part.