There are a wide variety of breast shapes that sometimes don’t correspond to the shape used in designing most ready to made bras, and underwires can both compound fit problems and help to work around some fit issues. Knowing which underwire works best for your breast shape can dramatically increase the comfort level of ready to wear, and for custom made lingerie and sewing your own bras, it opens up a lot of aesthetic possibility. Obligatory disclaimer: I don’t claim to be an expert. I’m just sort of obsessed with body geometry and fitting issues, and some of what I’ve picked up along the way might help people to attain better bra fit. I defer to people like Beverly Johnson (site here) for advice on fitting large busts and bloggers like Emerald Erin (great tutorials here and here) and Natasha of Arte Crafts for the more technical intricacies of underwire mechanics.)
With that said, on to breast shapes. Breasts come in a vast array of shapes and sizes and projections and levels of firmness or relaxation, and any shape of breast can be asymmetrical in size (in which case, a good workaround for support and comfort is to select a size that fits the larger and adjust the smaller with padding as needed or desired). Any breast shape can have certain placements on the torso, such as being wide set, narrow set, or with an outward or east/west placement on the torso. But most bras are drafted for the standard round shape, full on bottom, full on top, much like the shape of a breast implant, with a standard distance between breasts that point straight ahead.
If you have this breast shape and positioning, then you’re probably going to be able to fit well into most ready made bras without a lot of spillage or cup gape or underwire poking if you have the correct size. To illustrate this shape:
For other shapes, however, a standard bra drafted to fit a round breast might pose a variety of bra fitting problems. Breasts can vary in the shape of the breast root or base as well as in the way that the fullness is distributed on that base, and for these other varieties, a round cup often will gape, pucker, not provide the right support, or not correspond to the actual shape of the breast root (or inframammary crease).
Two shapes in particular, the breast with a narrow root or wide root, might find standard bras to be uncomfortable at the wire line/breast root as well as ill-fitting in the cup.
The narrow root shape (or sometimes called the slender shape) has a smaller diameter than the standard proportions assumed when designing underwires, so in an underwired bra, the underwire will rest below the actual breast root, and it won’t be as supportive or comfortable as it should. Standard underwires usually aren’t a good fit, though a custom bra maker can adjust cup fullness as needed to fit the wire that best fits the actual breast root. In ready to wear bras, different shaped wires like plunge wires might be more comfortable, and other possibilities like using cookies, padding, or full foam cups can help get a better fit.
The wide root shape (or sometimes called shallow projection or broad based) has a wider wire diameter to cup fullness proportion than the standard proportions assumed when designing underwires, so in an underwired bra, if the cup fits, the underwire will be narrower than the actual breast root, and may rest on top of the actual breast tissue or dig into it. If the wire fits, the cup isn’t completely filled by the breast tissue. A custom bra maker can adjust cup fullness as needed to fit the wire that best fits the actual breast root. In ready to wear bras, the best approach is to choose the bra with an underwire that fits correctly and then to add cookies or padding to fill out the cup. Cups made with stretchy fabric or lace can conform better to this shape than cups made with rigid fabric.
Other breast shapes vary in the way the fullness of the tissue is distributed, and these shapes may find that typical bra cups don’t fit them well.
The teardrop breast shape (or sometimes called swooping or fuller on bottom) has a distribution of breast tissue that is fuller on the bottom half and less full on the top. Standard round bra cups usually aren’t a good fit and tend to gape or pucker at the top. A custom bra maker can adjust the top cup fullness as needed to fit the breast shape. In ready to wear bras, choosing certain cup shapes can help achieve a more satisfying fit. Cups with stretchy or elasticated upper cups can conform better to the breast shape. Choosing cups with lower necklines and shorter cup heights such as demi or half cup styles and possibly some plunge styles are good choices, because the upper portion that would otherwise gape is absent or much shorter than fuller coverage styles.
The full on top breast shape has a distribution of breast tissue that very full in the top half of the breast. Standard round bra cups usually aren’t a good fit and tend to be too small at the top, causing spillage or “quad-boob” where the upper edge of the cup digs into the breast tissue and makes it look divided. A custom bra maker can adjust the top cup fullness as needed to fit the breast shape. In ready to wear bras, choosing certain cup shapes can help achieve a more satisfying fit. Cups made with stretch or elasticated upper cups can give somewhat to conform better to the breast shape. Choosing cup styles with lower necklines and shorter cup heights such as demi or half cup styles with vertical seaming (rather than horizontal) can avoid cutting into the tissue of the upper breast, though there may be a trade off with spillage potential.
The conical breast shape has a distribution of breast tissue that is more cone shaped than round. Standard round bra cups usually aren’t a good fit because although the wire line placement and projection amount may be the same, the amount of tissue volume to fill out the cup is less in a conical shape. A custom bra maker can adjust the cup fullness as needed, and in fact may find certain conical vintage cup styles to be a much better fit for this shape. In ready to wear bras, cups with push up padding in the bottom and sides of the cup can help the cup fit better, as can using padding inserts (cookies). Brands with shallower cup depth can be helpful, though this tends to flatten the tissue into a more rounded shape, which may not always be the most comfortable or supportive fit.
The omega breast shape (also called bell shaped or ball shaped) has a distribution of breast tissue that is one size at the wire line or breast root but becomes larger farther down the breast. This shape occurs over time and tends to happen with larger sizes. Standard bras are usually not a great fit for this shape because the standard relationship of wire size and cup fullness isn’t quite right for this shape and the wearer may find the wires of a cup that fits well are too large to stay at the inframmary crease. If wires are pushed lower by the breast tissue, this can cause discomfort against the chest wall and at the the underarms. A custom bra maker can adjust the cup fullness as needed and build in greater support to create a better fit for this shape. In ready to wear bras, full coverage styles with supportive, rigid cups that push the breast tissue towards the center front of the body are a good choice.
Underwires tend to take a lot of blame when it comes to ill-fitting bras, and in mass produced bras, it’s easy to see why. If your breasts vary from the standard shape and placement, it can be difficult to find a bra that has wire with the correct spacing in the correct sized band that also has the correct cup fullness. This is where sewing bras at home or having bras made to your measurements can make a world of difference. Lingerie manufacturers use wires made to their own standards, and shapes and lengths can vary greatly between them. These standards are usually not transparent to customers who are left to guess and experiment with fit at their own expense.
But custom bra makers and home sewists can choose underwires by relatively standardized shapes and sizes and get the fit and the style that they want. When an underwire fits the breast root and is placed in the right placement in a bra band that fits correctly, it shouldn’t shift, pinch, or chafe, and in my experience, can be even more comfortable than a soft bra. It can take a lot of measuring and a few iterations when you begin bra making to get this combination of factors balanced just right, but when you do, those results can be replicated again and again without the guesswork and fitting frustrations of ready to wear.
When shopping for ready to wear bras, the shape and style and flexibility of underwires are set by the manufacturer. But when you sew your own or have a bra made, you can decide if you want lighter gauge or heavier weight underwires, if you prefer them to have a lot of give or to be relatively unmoving, if you prefer wires with high sides or short sides, lower or higher center styles, and whether you prefer a narrower or more splayed curve.
For my own bras, I prefer shorter wires with a wider, more splayed curve, and these are some of the wire types I keep in my stash:
These wires are from three Etsy sellers that I find to be great sources for lingerie hardware supplies in general, and they seem to consistently stock all of these wires. I’m not affiliated with anyone in this list or anything, so my enthusiasm is quite genuine. 🙂 The regular heavy wire is a thick gauge, rounded wire from Porcelynne. This is the heaviest of the wires I usually use, and I’ve found the lack of a defined wire edge can actually make a big difference in comfort in partial band designs. The round and orange wires are from Emerald Erin, and these are flat wires in a shape I’ve bought from other sellers, too, but the ones from her shop have a heavier gauge and are more sturdy than most flat wires I’ve seen. She also offers a fitting pack for each of her styles where you get three sizes to see which is the best fit and this can be a bra fit game changer (because printing out pdf wire charts and cutting them out and scowling at teensy wobbly pieces of paper held up to your chest in your bathroom mirror is, in my experience, actually not all that helpful in finding the correct wire size). The plunge, shallow demi, and demi wires are from Arte Crafts, who has some great deals on larger quantities of wires and offers some harder to find wire shapes. These wires are the more standard, lighter gauge wire, which has a bit of flexibility to it.
When I started bra making I had some confusion trying to find exactly what I was looking for in a wire since wire naming conventions vary from seller to seller, and because it’s hard to know which shape is best for your body type. But it seems like there are a few sort of wire shape subtypes that most wires fall into. (I’m leaving out monowires and separator wires because I haven’t worked with these as much.)
There’s a “regular,” standard, day bra kind of shape, which has a moderate to high center front height and an underarm height that’s sort of high with a little bit of a splayed underarm curve. This is the kind of wire you might find in a fuller coverage, everyday style bra designed to be somewhat supportive and comfortable. Sometimes you can find variations of this wire shape that specify that they have a shorter wire at the underarm curve. (In Emerald Erin’s shop, this would be the “Round” and the “Orange” wires). These wires are great for standard bras and round breast shapes.
Then there’s a type of wire that is a taller, narrower version of the regular day bra, sometimes called vertical or strapless. The center front and underarm comes up higher and it may be a narrower curve with less splay at the underarm than in a “regular wire.” This kind of wire is great for providing support, and in strapless bras, they provide the structure needed to keep cups positioned where they should be. (In Emerald Erin’s shop, these would be the “Bliss” and the “Omega” wires.) This kind of wire would be great for omega breast shapes and narrow root shapes.
The plunge or push up wire shape has a low center and a regular height at the underarm, and is great for bra styles that plunge low and push breast fullness toward the center. This kind of wire would be great for a variety of breast shapes because the low center front eliminates certain cup fit issues, and helpful with breast placements that are closer or wider than the standard or for east/west breast positioning, since bras in this style tend to push tissue to the center front.
Demi wires are low at the center front and low at the underarm, and the curve is a wider, more relaxed curve than some standard wires. This is a wire that seems common in fashionable bra silhouettes with lower necklines. (In Emerald Erin’s shop, this is the “France” wire.) Arte Crafts offers a shallow demi wire that has an even more relaxed curve than regular demi wires. This kind of wire can be a great fit for breast shapes with a wider root or teardrop shape.
And the length of all of these wires can be modified even further if you are a crazy person armed with your grandpa’s linesman’s pliers, a heat gun, and some heat shrink tubing. 🙂 I hope this was helpful! (Earlier bra fitting rambles were anatomy of a bra and how to know if a bra fits, all about the bra band, and bust position and torso shape.)