Pattern Sizes are not the same as Retail Sizes. Patterns have consistent, standardized sizing from pattern brand to pattern brand. To figure out your starting pattern size, compare your body measurements with the pattern Measurement Charts. Match as many measurements as possible to find your pattern size. All Simplicity patterns are Multi-Sized to help you get a custom fit. Most likely your pattern size will not be the same number as your dress size. Please refer to the above link to view the pattern envelope to see further size information.