The Anatomy of a Bra

I have a good friend who is just starting to learn how to sew. She’s currently making corsets and skirts, and I keep encouraging her to start making bras, because ‘they’re easy’ I say. 

Today’s blog post is for all those who want to venture into bra making at home. I have provided a drawing with names of parts and pieces you may encounter, and below I’ll outline more about what I personally use and where you can purchase supplies for home bra making. 

Underwires
Might as well start with what I think is the most important piece of most bras, the underwire!

Getting good quality underwires, in larger cup sizes, can be quite a challenge! There are a few places online you can find different sizes, shapes and types. Wires can be made out of just plain metal, nylon coated steel, or even plastic. 

I typically choose a nylon covered steel underwire, and I try to choose one that is strong, yet flexible and doesn’t contort when I ‘spring’ it open.

Wires also come in different shapes. Balconette shapes, strapless shapes, plunge shapes, etc. You need to choose the right wire for your project so that it 1) fits into the bra when sewn and 2) is the right shape for the style of your bra. 

Sizing for wires is a bit unusual looking due to cross-grading or ‘sister sizing’. 34B is known as the industry sample size, so the wire size used in a 34B is labelled 34. A 36B will be 36, and a 38B, a 38. Because of cross-grading, a 34B bra is equal in cup size to both a 32C and 36A  - so both of those bras will also use a size 34 underwire. Below is a chart to show you the cross-grades.

This chart shows the cross-grading, or 'sister sizing' of underwires. The 'B' cup size is the base, as the wire size matches the band. Note, there are bra sizes outside of what is listed - the chart covers wired bras that I can find available commercially, with the exception of Ewa Michalak sizes as the company produces underwires exclusively for its own use based on the designer's own theories and ideas.

It's important to note that on small bands and cups (AAA/AA/A) the smallest wire used is a 30. In these bra sizes, the width of the cup and wire remains, and the depth of the cup will be reduced. I don't personally have enough experience to comment, but find the rationing sound. The same could be said for larger cups that at a certain point the wire should stop grading wider and deeper and rather the cup should become deeper. Again, I don't have quite enough experience here to comment, but would love to research this idea further. 

Straps
Straps can be thick or thin, stretch or non-stretch. A bit of stretch is nice for comfort, and it’s best to choose a strap width suitable for the size of the bra. A larger cup or band will traditionally have a slightly wider strap. 

When choosing a stretch strap, you don’t want a strap that is ‘too stretchy’ or you will find that the bra feels ‘bouncy’. For smaller sizes, choose a strap in the range of 40 - 50% stretch, and for larger cup sizes, look for something firmer with 40% stretch or less. 

Wing/Band
The sides of the bra are normally made from power net or mesh. The band of the bra does most of the work, not the shoulder straps, so again, it’s best to choose something suitable based on the size or level of support of the bra. The band can also be made out of rigid materials, but you’ll need to consider this when drafting your pattern and elasticate the underarm and underhand accordingly. 

Underband & Underarm
The top and bottom edges of the wing/band will be stitched with elastic. The width of elastic will vary depending on personal preference/comfort. In larger cup or band sizes, the elastic will be wider, but typically only along the bottom edge. You wouldn’t want a bulky half-inch elastic in your armpit!

Hooks & Eyes
These will come in various widths to be sewn on the back of your bra. One hook (19mm) is suitable for smaller bra sizes - although I have seen it up to a 36F! Two hooks are available as a narrow (28mm) and wide (38mm) and a 3 hook is around 57mm. Choose the width that you find most comfortable. Something to note - the hook portion of the bra will ALWAYS be sewn on the right hand side of the bra when it’s on the body, and the eyes on the left. There will also typically be 3 columns of eyes. This is so that you can tighten the band of the bra as the elastic wears and stretches. 

Rings/Sliders & Adjusters
You’ll need some rings and sliders for your bra if you plan to adjust the shoulder straps. I personally don’t use rings, and instead stock up on sliders. Sliders are available in metal, nylon coated metal, and plastic. For durability, I always choose a metal slider, and to make use of limited inventory typically stick with silver and gold for easy colour matching. 

You’ll need to make sure that your strap elastic fits nicely through your rings and sliders and can easily be adjusted. Choose a slider that is the same width as your elastic, or up to 1 - 2mm larger at most. If you choose to use rings to connect the strap to the front or back of the bra, you can usually get away with a ring a few mm smaller than your shoulder strap. 

Cups
This can be a bit more tricky. For smaller bra sizes, you can almost get away with any type of fabric in the cup if the breast will not put a lot of strain on the fabric. Larger cups need firmer fabrics, with specialist bra fabric being ideal. 

Lace, embroidery, firm nylon denier, simplex and duoplex are all fabrics that are traditionally used in bra cups - along with pre-shaped or moulded polyurethane foam. 

Centre Front/Bridge/Frame/Cradle
There are many names for this part of the bra, and it comes in many shapes, sizes and forms. This part of the bra, that connects the cups, is rigid and has no stretch. Typically, you would use a coordinating or matching cup fabric and stabilize the back with a layer of non-stretch fabric like the nylon denier, or with double-sided fusible interfacing, you could laminate two pieces of fashion fabric, alternating the grain lines for increased strength. 

A ‘cradleless’ bra will not have any fabric at the bottom of the cups, and the wire casing would be sewn directly to the bra cups, and not the cradle or frame of the bra. It will have just a small strip of fabric connecting the cups, or a small triangular shaped piece to attach them together. 

Misc. Notions
To complete your bra, it’ll also be helpful to pick up such things as wire casing if you’re making a bra with wires, bows for covering stitch lines at the apex, where the strap connects to the cup, and coordinating thread. If you’re wanting a truly professional look, you may also want some narrow denier to cover seam allowances, although I’ve not found a successful way to apply it without a specialist machine. 

Further Terminology
I wanted to include some other words that you may come across when looking at bra patterns or tutorials. One thing I noticed studying in the UK was the fact that the APEX was where the strap connects to the cup of the bra, and the POINT OF BUST was the deepest part of the cup, where the nipple would sit. In North America, and possibly other countries, the APEX would be the fullest point on the bust, so do follow instructions carefully. 

I also find that there are many names for a cup that has a panel on the side of the breast for an increased projected shape. Some may call it a side panel, power bar or sling. 

Below are some links where you can find the supplies needed to make your own bras at home. If I’ve missed anything, or you have a shop I should add, please leave a comment or send a message!

Note: I’ve only listed sources that I have personally used before. Searching online you’ll be able to find other retailers that have small accessories and a variety of fabrics. 

United Kingdom
Made by Niki eBay Shop (unit427)
Sew Curvy
Sewing Chest
Tissu Fabrics
Vena Cava Design

Canada
Bra Makers Supply
Farthingales 

Sweden
B Wear

Asia
Etsy for lace & embroideries
Lacebeauty
laceville