There is such a wide array of bra sizes that many times, a “sister size” may just work for you! Finding your sister size comprises of knowing your band and cup size and increasing the size of one while the other is reduced. This is extremely helpful to account for the differences between brands and styles. So, if you happen to measure yourself as a 34C, another store you don’t normally go to may find that you’re a 32D. The truth is, your body may not have changed, but a different band size can affect how much breast tissue a certain cup can hold. Variations in these measurements are pretty common since not all bras are created the same way.
First, you’ll want to find your true bra size and make sure that it fits in all the right places. Then, if you decide on changing style or brand, you’ll be able to try on a few slightly different bras that may work for you. If you plan on trying a band that is one size larger, you have to adjust by decreasing the cups by one size. Alternatively, if you try on a reduced band, the cups should increase. Sister sizing does work, but only if one measurement is changed by one or two sizes. After that, the bra may be too large or too small overall.
How to decide on where to size up or down
If your breast is spilling out of your cup, then you should aim for larger cups and a smaller band. If there are signs that you have a tight band, such as your bra making your back bulge or leaving marks, then you should look into a something which increases your band size and decreases the cup. Be sure to reduce band size if both cups and band are too large, and shoot for a larger band if both are too small. Bands are designed to take most of the weight of your bust- not the straps- so it’s the most important part of your bra. Many problems can be avoided just by making sure you have the most supportive band, and this applies to sister sizes as well.
Another way to determine which sister size to try is to pay attention to where you hook your bra. If you can connect your band to the tightest hook, you most likely need to decrease your band and go up a cup size. On the contrary, if you can only connect it on the loosest hook, then you would benefit from a larger band. If the middle hook works just right for you, then you’ve found the right sister size!