Even I hadn’t heard of the concept of Sister Bra Sizes till a few months back. You must be wondering what a Sister Bra Size is. Well a Sister Bra Size is basically the bra sizes that surround your current bra size.

The hidden secret to sister bra sizes is the fact that you will realize that you can actually fit into more bra sizes than your current bra size.

How the concept of Sister Bra Size works?

We usually buy a Bra by opting for the right cup and band size. What you don’t know is that there is a relation between the two.

Fact : Bra Cup size (cup volume) is relative to the Bra Band Size. So when your band size increases say for example from 32B to 34B, the cup volume gets larger.

Based on this concept you will find that more cup sizes have the similar volume even though they do not share the same band size. Bra sizes with the same Bra Cup volume, although labeled with varying cup sizes are termed as Bra Sisters Sizes.

So how do you find your Sister Bra Size?

There are tables that will help you determine your Sister Bra Sizes. The sizes in the same color or the same row are all sister Sizes. They have the same cup volume as your bra size.

For example , if you wear a regular 34 C, then your bust may also fit into a 32D or even a 36 B sized bra.

Figuring out a Sister Size requires a set of one-size shifts, in opposite directions, in the numbers and letters of bra sizing.

Remember that the cup changes in “name” only ; the band’s number size and actual length changes.

Sister Size DOWN = one actual size smaller than your current Band size AND one letter name larger than your current Cup

Sister Size UP = one actual size larger than your current Band size AND one letter name smaller than your current Cup

Bra sister-size

Let me give you an example with different instances :

1) If the band fits, but the cup doesn’t

Solution : Change the letter but not the number

Example : If your size is currently 34B then you might want to go to 34A or 34C depending on whether you need a bigger or smaller cup.

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2) If the band doesn’t fit but the cup fits

Solution : Change both the letter and the number diagonally

Example : If your size is currently 34B and the band is loose but cup is correct you need to go to 32C to make the band tighter and make the cup remain unchanged.

Similarly if you are a size34B and the band is tight then you need to go up a band size and go down a cup size as the cup size remains unchanged.

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3) If both the cup and band size need adjustment

Solution : You need to adjust the number but not the letter

Example : If your current size is 34B and both band and cup are too loose then you need to go to 32B. The cup size remains unchanged as when we go down band size the cup automatically reduces in volume.

Similarly if band size and cup size is too tight then you need to go up a band size without changing the cup size. The cup size remains unchanged as when we go up band size the cup automatically increases in volume

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In short : Many bra sizes can fit your bust! See which bra sizes that have same cup volume in the bra sister size chart.

Remember :  Different “bra sister sizes” can be used by the same woman (cup volume will fit). But it is no guarantee that all band sizes will fit. So remember to always try bras on!