Hi All!

Underwires. It’s a big topic, and I hope that I can shed some light on it, to take some of the mystery out of bra-making!

Since this is my first theory post in Bra-A-Week 2016. I want to start off this post by saying: there is no universal right or wrong, everything is a matter of preference. Bra-making and bra fitting is a very intimate and personal thing, and everybody has a different way that they like to make and fit their bras, and I’m happy to help by sharing my opinions and things that I’ve learned in my bra-making experiences and I hope that you’ll leave your opinions and experiences in the comments too πŸ™‚

The Basics:

Underwires are meant to help support and distribute the weight of breast tissue into the band of the bra. They also help to give more shape and lift. Underwires should not be uncomfortable or painful.

Underwires are generally made of steel, and can come in different gauges (thicknesses) that have different strengths and levels of flexibility. The thinner the wire, or the more flexible the wire, the less support it will give, and the more it will bend from its original shape. The thicker/stronger a wire is, the more support you will get and the more it will hold its shape. I prefer to use a wire that is thicker and stronger for more support, shape and lift. I use a 24 gauge wire, and that is the gauge of wire that I offer in my shop.

Now the more challenging part: fitting an underwire.

Underwires come in different sizes, lengths and shapes.

The size and the length of underwires are pretty straight forward.

SIZE: Size of an underwire is about the overall diameter of the breast and is often calculated by your band and your cup size, as your cup or your band size increase, so will the diameter or your wire. In the industry they have pre-determined the diameter of a breast for each size of bra (e.g.. 34C is a 36 size wire). As we know- this is a ‘standard measure’ and just because you have a certain cup and band size, doesn’t mean that you will be that wire size- and we have the luxury in making our own bras to find the wire that fits our own unique body, instead of going by a standard! πŸ™‚

LENGTH: Length refers to the length of certain type of wire (surprise! lol). Generally speaking, length will refer to the length of the wire at the centre front, because this length will indicate the height of your neckline, wether you are making a plunge bra, or you want something more full coverage at the centre front.


Now the shape of the underwire can take a little bit more thought and examination. This is something that I haven’t seen talked about very much online, and that I’ve had to figure out through many fittings and talking to people who struggle with underwires. So what I’ve generally found is that breasts come in different shapes. And when I say different shapes I’m talking about the shape of the crease between breast and body where your underwire should be sitting.

I’ve found that people can be more ‘tall ovals’, ’round’ or ‘wide ovals’- somewhere on this continuum of shapes.

(please forgive my mediocre drawing skills, I think the tall oval and the round could have been little more distinct- but alas, it’s good enough to get the point across)
People can fall in a lot of places on this line, but I find that the people who have the most challenges fitting underwires are the people who fall more to either side.
People who have a tall oval shape, are generally more likely to have larger cups on a smaller frame (because that’s the only way they fit!), generally there is not much space between breasts and they need a wire that is deeper with long arms and goes up straight at the centre front. So if they have a wire that is too shallow and splayed, they will have to be spaced too far apart, they won’t get the support that they need, and it won’t sit flat against the chest in the centre front.
On the other hand, people who are more of a wide oval shape are more likely to have smaller or shallower cups, spaced further apart. They might find that the regular underwires that fit width-wise across their breast have a gap at the bottom where it extends below where their breast tissue ends, and they find that the arms of the wire are too long at the centre front and under the arm. They need a wire that is more shallow, and splayed to fit comfortably.
This is the main goal that I’ve been working on with my wire selection in The Emerald Studio: finding different shapes of wires to suit all the different shapes of women πŸ™‚ Β So I will show you, using the wires I have available, which shapes I find help for different shapes of breasts. *these are all wires that I have available, but these shapes, styles and fitting elements are things that you can look for in any underwire*


Here are sample wires all in the same size (38) to show the difference between them, and how they are meant for different shapes.

The Bliss is meant to help women who are the “Tall Oval” Β (you can see how the tall oval would rest well in this wire)

The Round is meant to help women who are a more round shape (you can see how a round breast would sit well in this wire)

The France is meant to help women who are a more “Wide Oval” Β (you can see the wide oval sitting well in this wire)

The Plunge is generally for the tall oval or round shape that is looking for a plunging neckline.

You can see from the shape of these wires, how the breast is meant to sit in them, and how some would be better shapes for different shapes of breasts

Here is a closer breakdown of each type of wire:

The Bliss

You can see that The Bliss wire has ‘deeper shape, and is slightly more narrow in width, and at the centre front it is very vertical, which means that you can bring the two wires very close together in the centre front for women who find that they have no space between their breasts. This wire also has a little bit of the roundness reduced at the outer bottom edge, to help push the breast tissue out from under the arm and towards the front.

The Round

The round wire is a very standard shape of wire. It is, as the name would say, very round, with a more gentle amount of splay at the centre front. This is a really good wire for people who have a very round crease where their breast meets their body, and generally these ladies will have fairly proportionate breast-to-frame ratio.

The France

This wire was inspired by a good friend, who had a hard time finding any wires that would fit her shape. This is a very shallow wire for women who find they are more of a ‘wide oval’ shape, you can see it has a gentle curve at the bottom, and the arms are very splayed. The arms of the wire are also quite short under the arm and at the centre front to suit this shape.

Now the France wire can be worn by women who are the wide oval shape, and they will fit in a similar way to a round wire or a bliss wire on the women who suit those shapes. But the France wire can also be worn by women who have other shapes, who want a wire that is much lower under the arm, for different styles of bras, or more relaxed fitting bras (that’s how I like to wear them, even though I’m not a wide-oval). They are a more versatile and relaxed wire that can suit different shapes and sizes.

The Plunge

The Plunge is a good example of a different length of wire. You can see from the plunge that the underarm edge is similar to the Bliss and the Round wires, but it is much lower in the centre front, to suit the plunging neckline styles.

Because of the height of the underarm edge, this style might not be the best for a ‘wide oval’ shape, since the underarm would sit too vertically and high, but it is a great option for plunging necklines for tall ovals and round shapes.


Now that you know a little bit more about underwires, I’ll use myself as a case study, since I’ve worn all of these underwires, and know quite a bit about my shape.

I find that my shape is somewhere between Round and Tall Oval. I can comfortably wear both the Round and the Bliss wires, but I find that the Bliss wires are more flattering for me: as you can see from this photo from Bra Theory September. (Bliss wire on the right of the photo is a slightly nicer shape for me)

I’ve also shown the France wire in my latest bra. Now I’m not the standard ‘wide oval’ shape for this wire. But you don’t HAVE to be that shape to wear the wire, I wear this wire as a much more relaxed fit, low under the arm, lower in the front. You can see that it’s not giving me the same shape as the Bliss or Round wire and offers less support for my shape, but it is pretty for more dainty lingerie looks πŸ™‚ Β and would also be comfortable for more lounge-bra styles.

And finally the Plunge, you can see that I’m getting the same amount of support and shape under the arm as I would wearing a Bliss wire, with the higher under arm- which is helping to push all my breast tissue forward (yay for cleavage!) and then the wire is nice and low in the front for that plunging neckline πŸ™‚


Underwires take a little bit of trial and error before you find the perfect ones for you. And if you don’t like underwire at all, you don’t even have to wear them, there are nice no-wire options too! It’s all about trying new things and finding out what works best for you.

What are your underwire preferences? Did you learn anything new from this post?

Let me know!

Happy Sewing

xo erin