Do You Know Your Sister Size?

Do You Know Your Sister Size?

So many women have NO idea what a sister size is… And FYI, it’s not your sister’s size.


The concept of a sister size is simple; if you fit in one bra size, you’ll likely fit into a couple of other sizes too and it will revolutionize the way you choose your bras.

Chances are you learned that you had one bra size, and that was the end of it. If you were a 12B, then you were a 12B in everything. Of course, unless you fell pregnant and began feeding, in which case you were likely to change your bra size. So you probably won’t believe us when we say that if you’re a B cup, you could also be a C and even a D cup. But it’s true.

So here’s how it works. A bra size isn’t like your clothing sizes, it isn’t a case of a 14 being larger than a 12 and that’s the end of it. Bra sizes are more like ratios than linear sizing. The band size will vary with the volume of the cup (how much breast tissue it can hold). If you go up a band size, you’ll go down in cup size. It all sounds pretty confusing, so we made a handy chart to help you calculate your sister sizing. Find your size in the chart, and your sister sizes are the ones in the same row – going across. For example, if you’re a 10C then you could also fit an 8D or 12B.


Sister Size Chart

The great thing about sister sizes is that even though they may look counterintuitive, they’re perfect for finding a great fitting bra. If you’re wearing a 12C and the cups fit perfectly, but the band is a little too small, you might think you’re a C cup so you’ll try sizing up to a 14C. You’d probably find that this would make the band fit well, but now the cup is too big, the reason being that a 14C’s sister size is 12D. So instead, you should try a 14B (up a band, down a cup).

Hopefully this makes sense, but if you’re still a little unclear feel free to book in for a fitting. We offer FREE fittings Monday – Friday, 9 am – 5 pm. Just email us HERE.


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