The basic bra sizes from 34-38A-D are fairly simple on the bra manufacturing scale, however, when a bra is sized up, it takes more engineering than, say, a t-shirt. When manufacturing a t-shirt, you really only need to make it wider around, maybe a little bit longer. For a bra, there are so many aspects that need to be adjusted, and sheer size is just one of them.
Full bust bras, by the very nature of needing to support a greater volume of weight, have multiple further considerations that aren’t applicable to core sizes, if a company scales up a 36B to a 30DD with no structural changes, the wearer might have straps digging into her shoulders, fabric stretching too far, and underwires bending all over the place.
Almost every aspect of a bra needs to be readjusted for larger cup sizes, starting with thicker straps. Pretty, thin elastic straps are probably not going to cut it. Although most of the support of a bra should come from the band, the straps often need to be made of thicker, sturdier elastic for D+ cup styles. It’s more expensive to source multiple widths of the same elastic, and it can change the look of the bra, so manufacturers who are sizing up often skip this detail during development. However, stretched-out, rolling elastic is not a good look, and not a helpful feature. In general you really get what you pay for when it comes to a bra.
Another aspect that is sometimes overlooked during grading is the need for sturdier fabrics. Stretch-lace bra cups are so pretty, comfortable, and delicate-looking, but they just don’t work for larger cup sizes. Cute stretch lace bras that come in larger sizes are like roller coaster rides; they start with joy and excitement and end with immediate disappointment upon trying them on. It often feels like wearing a crop top with an underwire. When materials are sturdier, bras are more supportive.
If you’re interested in a stretch lace cup that comes in larger sizes, check to see if it has a non-stretch mesh or similar thin woven fabric lining that will keep the cup from stretching out as soon as you put it on. Plus, check the stretchiness of a band’s fabric.
Side slings are a small but important addition. Slings are those strips of fabric on the inside of a bra that stretch across the bottom outer corners of the cups, most often seen in soft, smooth cupped bras. They help lift the tissue up and out, and can be the difference between a bra that has decent lift and a bra that is shockingly comfortable, very supportive, and provides a narrow silhouette.
If you have ever worn a bra in a larger size with a thin plastic underwire, you know how important more rigid wires are. Full bust blogger Sweet Nothing‘s interview with Kim Hamilton, the brain behind the full-bust-focused business Kimtimates, illuminates a lot of the unique challenges designers face when making larger bras. And although she speaks in particular about the G+ market, many of these concepts are applicable to the smaller full bust market as well.
“Developing a heavier gauge wire for stability is key in larger sizes,” says Hamilton, who wrote a four-part series on underwire education, so she definitely knows what she’s talking about. When a bra feels like it’s bending over your ribcage as you move, a flimsy underwire could be the culprit. Look for bras with metal wires instead of plastic ones, and thicker wire over thinner.
One more reason that it’s not enough to simply grade a pattern up evenly: breasts don’t get larger evenly. Larger breasts have more projection, and need more space because of it. Which brings us to perhaps the most important aspect of a full-cup bra: specially-developed patterns. Since many sizes share cup volume with one another, an easy way to make a bra in an extended size (and what I assume many brands do) is to simply grade up, or scale up, a pattern.
But even if the calculations for breast volume are correct, larger breasts on a smaller frame require different shapes for the best support. “A wire for a 38D could be used to make a 32F, but those two bodies are likely to have very different breast shapes,” says Williams. “It’s much better to create a specific pattern just for that size segment, fit it on bodies of women in that size segment, and alter grade rules and pattern shapes to work specifically for them.”
A pattern change isn’t typically noticeable. However, when a brand just can’t get a bra to work at larger sizes, they’ll sometimes change the style from a demi cup to a full cup past a certain size. In those cases, the bra just won’t be supportive for larger sizes in the original shape, so the design team makes the decision to alter it. It can be confusing and frustrating to try on a cute demi bra, only to find that your size has much more coverage. However, the support wouldn’t be there otherwise.
So next time you lament that a pretty bra doesn’t come in your size, consider that if it did, it might look like a completely different bra. Or it might not support you the way you want it to, but it is necessary to get the perfect fit, lift and support when going beyond the DD.