This is a very common problem among women and can be a huge source of discomfort. The most common mistake is wearing a back band that is too large and compensating with cups that are too small. The problem originates in using archaic measuring methods on bras constructed of modern materials. When the bra was first introduced, it was made of linen, which doesn't stretch. The patterns that bras were cut from required that the wearer add 4 to 5 inches to their underbust measurement in order to get a good fit. Nowadays, bras are constructed of highly elasticated materials cut from the same old patterns; however, many people are still also using the old fitting method. Because newer bras can stretch several inches, this now results in band that is much too large. The majority of the support should be coming from the back band, so if you have a band that is too loose, the weight of your bust is inappropriately distributed to shoulders, and the underwires will dig in and rub, causing tremendous discomfort.
Here are some examples of a poor fit:
1) This red line marks where the actual breast tissue is. As you can see from this, the cups are very clearly too small and sitting on top of the breast tissue.2) The center gore of the bra is not laying flat on the sternum; rather it is pushed out away from the sternum, another indication that the cups are too small.
3) The back band is hitching a ride north.
Here are a few questions to ask yourself that may indicate you are wearing the wrong size:
1) does your back band ride up your back (i.e. it doesn't sit horizontally, parallel to the floor, but rather angles upward?)
2) can you pull your back band out more than 2 inches from your back?
3) do your shoulder straps take most of the weight of your bust and leave grooves in your shoulders?
4) do your breasts appear to sag, even when you have a bra on?
5) do you suffer from back or neck pain?
6) when you lift your arms, does your band pull away from your ribcage?
All of these are signs that your back band is too big. A band that is too big will make your breasts look saggy (when the back goes up, the front goes down).
Moving onto the cups, underwire should not ever be uncomfortable. If it sits properly, encasing the breast tissue completely, it will provide support for the breasts, rather than causing pain. If your cups are too small, then you can't fit your entire breast in the cup, resulting in some of the breast tissue being alienated from the cup. Over time, this tissue finds a new permanent home and often ends up in some place you don't want it, like your armpits. Fat rolls in your armpits are oftentimes migrated breast tissue, that has gone in search of other places to live, because there's no room for it in too-small cups. This can be remedied only by wearing the correct bra size and inviting all that tissue back into the cups.
Although I am an advocate of not using a measuring tape to find your bra size, I acknowledge that this is the only way really possible when giving instructions over the internet. So grab your tape measure. You'll want to put on your best fitting bra in order to take these measurements.
First, measure under your bust, making sure the measuring tape is parallel to the floor. This measurement should be snug. Write this number down.Next, you're going to take your bust measurement. You'll want to measure loosely over the largest part of your bust, again keeping the tape parallel to the floor. If your breasts sag, you might want to lean forward slightly to take this measurement, in order to be more accurate. Write this number down as well.
Now, take those two measurements and enter them into this calculator. The size the calculator returns might look completely absurd to you, but that's only because places like Victoria's Secret have done such a great job of making women believe that the only sizes that exist are 32-38 A-D.
Keep in mind that the bra size given by calculator is only a ballpark estimate, and you must try bras on to make sure that they fit. You'll want to go someplace that has a wide selection of sizes - in the US, I recommend Nordstrom - and grab the size the calculator recommended for you, as well as several sizes around that size. For example, if the calculator recommended you try a 30F, you'll want to grab the following sizes to try: 30F, 30FF, 30E, 32DD, 32E, and 32F.
When you are trying on your bras, it is critical that you put them on correctly. Many women just toss their bras on, but there's actually a right way and a wrong way to put them on. To correctly put on your bra, you'll want to fasten the band, and place your breasts in the cup, slipping the straps over your shoulders. Then you'll want to take your hands and scoop the tissue under your armpits into the cups. Then give yourself a jiggle to settle into the cups and make sure the straps are correctly adjusted to a 2-finger tension.
Now you'll want to assess whether the bra you're wearing fits. Here are the things you should look for:
1) The back band should be very firm on the loosest hook, and you should not be able to pull it more than an inch or two from your back. Any farther than this, and the band is too big. However, if you cannot comfortably slide two fingers under your bra band, it is too tight.
2) The back band should be sitting horizontally all the way around your body, and should not be riding up toward the back. If the band is angled up toward the back, it is too big.
3) When you raise your arms, the bra should remain rooted firmly against your ribcage. If it pulls away, the band is too big.
4) The center gore of the bra should sit flat against your sternum. If it sticks out, your cups are too small.
5) The tops of the cups should make a smooth line with the tops of your breasts. If the materials digs into the tops of your breasts, the cups are too small. If there is excess material and bagging at the top of the cups, the cups are too big. However, if you have the material cutting in at the top of your breasts, but you have wrinkling and bagging at the nipple or bottom of the cup, it actually means the cup is too small.
6) The underwire should sit behind the breast tissue, completely encasing it. It should not sit on top of it; if it is, the cup is too small.
If you need to change band sizes, it is important to note that cup sizes are relative to band sizes, i.e. the cup on a 34B is NOT the same as the cup on a 32B. The 34B cup is one cup size larger than the 32B. A 32C has a cup volume equivalent to the cup volume of the 34B. So if you go down a band size, you need to go up one cup size, and if you go up one band size, you need to go down one cup size.
It may also be important to note that if, when trying your new bra size, you feel that the band size is too small, it may actually be that the cups are too small, pulling the band taught and making it feel tighter than it actually is. Always try going up a cup. The correct cup size should be the largest cup size you can fill out completely.
One other important note is that you should try on different styles of bras, because the wrong bra style in the right size will still cause fitting problems. Particularly, you'll want to see if you need wide or narrow underwires. For narrow underwires, try Freya, and for wide underwires, try Panache.
Also note that lingerie advertisements largely cannot be trusted. Most often, models are placed in atrociously fitting bras and the most obvious problems are simply photoshopped away. It's important to find bra retailers that offer a wide range of sizes; trust me, sizes like 30F, or even 28J exist! Going shopping at a store that offers an abysmal range of sizes almost guarantees you'll be put into the wrong size.
Check out this excellent example of a proper bra fitting:
This video has English captions if you do not speak Polish; if the captions do not automatically show up when you start playing the video, just push the [cc] button down at the bottom of the video and it should display the captions.
