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Sizing Guide

Sister Sizes

Your current bra size has "Sister Sizes" - alternate sizes where the cup volume stays the same even though the band size and cup letter changes. This means that even if we don't have your bra size in stock, you can still order a bra that fits you, by choosing the corresponding Sister Size.
 

Find your Sister Size

Your bra size has two Sister Sizes going "up" and "down". "Up" means that the Sister Size is one actual size larger and one letter name smaller than your current bra size. "Down" means the opposite - one actual size smaller and one letter name larger. For example, if you wear a 38B, your Sister Size Up would be 40A, and your Sister Size Down would be 36C. You can wear either one of the Sister Sizes and still have the same cup volume as 38B! The only difference is that you'd probably need to use the furthest or the tightest hook of the bra, instead of the middle one.

Our Sister Sizes Guide

The chart below will help you find your Sister Sizes. Just look for your actual bra size in the middle column.

Sizes in pink are stocked by BackStory.

 
30 Band Size
Sister Size DOWN Current Bra Size Sister Size UP
28DD 30D
32C
28DDD 30DD
32D
    
32 Band Size
Sister Size DOWN Current Bra Size Sister Size UP
30D
32C
34B
30DD
32D
34C
30DDD 32DD
34D
    
34 Band Size
Sister Size DOWN Current Bra Size Sister Size UP
32B
34A 36AA
32C
34B
36A
32D
34C
36B
32DD
34D
36C
32DDD 34DD
36D
    
36 Band Size
Sister Size DOWN Current Bra Size Sister Size UP
34B
36A 38AA
34C
36B
38A
34D
36C
38B
34DD
36D
38C
34DDD 36DD
38D
     
38 Band Size
Sister Size DOWN Current Bra Size Sister Size UP
36B
38A 40AA
36C
38B
40A
36D
38C
40B
36DD
38D
40C
    
40 Band Size
Sister Size DOWN Current Bra Size Sister Size UP
38C
40B
42A
38D
40C
42B