Sister size bras are the bras those have the same cup volume as your actual size bra. These are the alternative sizes of your actual bra size. A perfectly fitting bra feels snug yet comfortable. The band sits perfectly parallel to the floor and doesnt ride your back.Bra Sister Sizing, Explained | Better Homes & GardensJun 05, 2019 · For example, a 36A is the equivalent to a 34B, a 32 C, and 30D. Mind-blowing, right? Sister sizing is also why so many women are wearing the wrong size bra. Most women are in the right volume or within the right sister sizing group, just wearing the wrong size underband, Tempesta says.Bra Sister Sizes: The Bra Fitting Secret You Need to Know bra sister sizes6 rows · Knowing your sister sizes can help you find your best fit when buying bras that run smaller or bra sister sizes 30B 32A 34AA 30C 32B 34A 30D 32C 34B 30DD 32D 34C See all 6 rows on www.upbra bra sister sizes