What Are Sister Sizes?
What are sister sizes?
When two bras are in sister sizes, it means they share the same amount of the volume in the bra cups, but different band lengths.
How do sister sizes work?
There are two components of a bra size: the BAND SIZE, and the CUP SIZE.
BAND SIZE corresponds to how wide your ribcage is.
CUP SIZE corresponds to how much volume your breasts have.
When two bras have sister sizes, it means they share the same amount of the volume in the bra cups, but different band lengths.
For example, 36C and 38B are sister sizes. Their cups are made for the same breast volume. Only, the 36C has a shorter bra underband than the 38B.
Can you wear them interchangeably?
Only if you are kind of in-between band sizes. If you are between 36 and 38 in band size, you can probably make both 36C and 38B work.
However, if you are on the smaller side of 36C (for band size), the sister size that could work for you is 34D. On the other hand, if you are on the bigger side of 38B (for band size), the sister size that could work for you is 40A.
So, does that mean 34D and 40A are sister sizes? Absolutely not. We do not recommend wearing a sister size that’s more than one “sister” off. 36C and 38B is ok. 36C and 40A are not. The band length difference is too much – a 36 band is likely going to be too tight for someone who usually wears 40, even if you are on the smaller side of 40.
Hi Sefe, if you like the cups on 32H, but find the band a bit restrictive, we recommend 34G. Alternatively, you could get a band extender and use it with the 32H until the band relaxes over time.
Hello. I just got my first bras from Understance and I think I am hooked. I really love the quality of the bras!
I used the bra size calculator and got the Harper smooth lace Flexwire bra in 32H. I was shocked at first because I thought I was a 34DD. The cup is my perfect size but the band is a bit restrictive.
For context, I also bought the Luna Wireless Support Full Coverage Bra in 34DDD because there was no 32H left and I thought it might be my sister size. (I am not sure of this though)
The band is perfect and does not dig in like the 32H but the cup fit is not so good. What bra size will you recommend that I get next? And what is my sister size? Thank you so much in advance.
I usually buy a bra size 36DD and I fasten the hooks on the tightest or farthest setting? I’s read that you should start with a new bra hooked on the closest hooks (to the end) so you can move to the other “settings” as your bras loosens up and stretches a bit. Is that true ? And should I be buying a band size 34 instead? And what is my “sister size”?
Thank you. I know I’ve asked several questions.
Hi there, to get the most use out of your bra, we do recommend hooking it at the loosest setting to start. This way you have some room to make it tighter once the bra stretches out. The tighter sister size to 36DD would be 34DDD.