Whether you're looking to buy a bra or learning to sew your own, knowing how to name the parts (and the job each is supposed to do) will help you on your journey!
The bits in the back
The majority of underwire bras have a back closure. This allows you to put on the bra without dragging it over your head.
Hook and Eye
The hook and eye closure is the most common type of closure. It has "eyes" on one side that face outward from your body, and "hooks" on the other, that face in toward your body. Most bras have 2-3 columns of eyes, allowing you to tighten the band as the elastics relax over the life span of your bra. Depending on the design and width of the bra band, it could have 1-5 rows of hooks and eyes.
When you're buying or making a bra, the bra should fit you comfortably on the last set of eyes - leaving you two columns to tighten the band.
Back Band or wings
The part of the back band attached to the hook and eye closure is called the back band or the wings of the bra. The design of these can vary widely, but generally the back band is made of stretchy material that helps the bra hug your body while allowing you to move and breathe.
If you are looking for a bra with greater support, particularly for larger cup sizes, a wider back band made of firmer materials or multiple layers of fabric should provide better support.
The bra band should feel snug but not tight, and should hold the front frame in place as described below. Getting the band to fit is the first step toward finding a great fitting bra. Don't overlook this by getting fixated on the cups, which is where so many of us get hung up!
Many bras have an adjustable section of elastic to help you vary the length of the bra strap. It can be in the back, as pictured here, or at the front.
When you're shopping, look for a bra that leaves you room to adjust the strap - if it's already tightened as far as it can go, you are going to have straps falling off your shoulders after a couple of days. Test the adjuster by pulling on the straps, to make sure it will stay in place and not slide with wear.
The front of the bra
This is the front of a full band underwired bra. How do you know if your bra is a full or partial band? Flip it so that the inside of the bra is showing and look at the elastic that runs along the bottom of the band.
If the elastic runs from the hook and eye closure, along the back band, and underneath the cups of the bra, it's a full band bra.
The straps of the bra include all the material that isn't part of the adjustable section (whether it's at the back or front of the bra.) It can be made of fabric, lace, elastic, and different combinations of all three!
When you're shopping for a bra, look for straps that have very little stretch or give. The more stable it is, the better job it will do holding up the cup. The straps should rest comfortably on your shoulders without digging in.
The cups are the part of the bra that contain the breast tissue or prosthetic. In a bra that fits properly, the bottom edge of the cups sits exactly where your breast meets your chest wall, all the way around. The bra pictured here is a full cup bra, which means it encloses all the upper breast. Different bra styles provide different levels of coverage at the upper breast as well as different shapes. The style you choose will depend on your preferences and the job you want the bra to do.
Cups can be made of different fabrics, lined or unlined. They can be made from cut and sew foam, or seamless foam (commonly called t-shirt bras.) The job of the cup is to hold the breast tissue in a specific shape.
A cup that fits you first and foremost is a cup that holds all your breast tissue with the wire sitting in the correct position and the bridge touching your chest wall. You shouldn't fall out of the cup when you bend over. There shouldn't be large wrinkles or spaces inside the cup. The top of the bra shouldn't cut into your breast tissue, leaving a visible line or bulge on either side of the strap.
The underwire and channelling
The underwire sits in a tube of fabric called channelling or casing. It follows the bottom edge of the cup around the breast. If the bra fits you, the wire should sit exactly where your breast meets your chest wall, beginning in the space between your breasts and ending toward your armpit. It should rest flat, with no gaps, and without tilting or digging in.
The front frame
The front frame of the bra is the material that sits between and underneath the cups. It is generally made of a stable (low stretch) material. The part between the breasts is called the bridge.
On a bra that fits, the bridge rests back against your chest wall - there is no gap between the bra and your body. The frame underneath your breasts does not roll or dig in.
Those are the basic parts of a full band underwire bra!