For Bras :
Due to cup grading of sizes, one can wear several sizes well because of the multiple hook and eye fastenings offered on the back of bras. For example, someone wearing a size 34C (AU-12C) can also wear a 32D (AU-10D) or 36B (AU-14B) . See below table for other interchangeable sizes.
For panties, slip and lounge wear :