To begin, stand next to a mirror in a room with good lighting. Wearing just your bra (fastened on the loosest hook if it is new), ‘scoop and swoop’ your breast tissue fully into the cups (see “How to Properly Put on a Bra”). Then, let your breasts settle into it by walking around, jumping, stretching, etc. You are now ready to examine the fit of your bra. There are four main areas on which to focus your attention: band, straps, underwire, and cup.
Most importantly, the band should not be riding up in the back, nor should it be falling down in the front. These are signs of a band being too loose. A quick, easy check is to try the “two-finger test”: if you can fit more than two fingers between you band and your torso, it is too large.
A band feeling too tight is most often caused by too small of a cup size, which can put pressure on one’s torso. To test the length of the band, close the bra with the cups in the back. The band should be very snug, and the wire should not move and rub. However, if you have a relatively fat-less torso, causing the underwire to seem to be painfully “clacking” against your ribs, the band may truly be too small.
If straps are causing indentations or pain, that is typically also a sign of a band being large. Loosen your straps until you can comfortably fit two fingers between them and your skin. If your breasts sag when you do so, you were using the straps to over-support them; your band should do most of the work supporting your breasts. If you’ve already tried such, it is likely that the cups may be too large or the bra cut is incorrect for your shape.
The underwire should rest on the “root” (where your breasts are connected to your chest), and the center gore should rest in between your breasts. No part of the underwire should ever rest on breast tissue, whether underneath or on the sides, and it shouldn’t ‘float’ anywhere. If the gore doesn’t ‘tack’ by touching your torso in between your breasts, the cups are likely too small. However, four other things could be wrong: the cups could be too shallow for your shape, the cups could be too wide for your shape, the band could be too tight, or the underwire could simply be too flimsy for your breast weight if you’re an H-cup or above. If the underwire pops out the bra, the band is too large or the wire has been overly distressed by a cup that is too small.
If the cup reaches to the sides further than your breast tissue, you may have either close-set breasts or narrow roots, which can be amended by seeking out brands that make less-wide cups.
Another common issue is ‘quad-boob’, which occurs when breasts spill over the cups either on the tops or out the sides, giving an impression of four breasts. If this occurs, the cup is typically too small. Quad-boob can also be caused by cups not suited to one’s shape, or, more rarely, too tight of a band.
A wrinkly bra cup usually indicates that it is too large or the style of the cup isn’t suited to your breast shape. On the other hand, wrinkles in a specific starburst-pattern around your nipples indicate a cup that is too small.
As far as one cup fitting and the other not, there is a difference of breast. Breast asymmetry is very common. Just make sure to choose a bra to fit the larger breast, and put removable padding or a cutlet in with the smaller breast to fill out the cup if necessary.
A properly-fitting bra will not blister, chafe, or scratch you anywhere, and this can be caused by an ill fit or by bras that are made with cheap materials. If experiencing rashes, redness, or soreness on the underside of the breast, then the cup is likely too small.
Most importantly, a bra should be comfortable and flattering. Even if it meets all the requirements, such as breasts contained in cups, flush band, and comfortable shoulder straps, if it still makes your boobs pointier than you’d like, gives them a weird shape, or otherwise affects your confidence, try another bra.
Breaking it down, Hayley.