Check the band first
A loose band lets the whole bra shift, and wires that would sit correctly end up in the armpit. Look side-on: if the band rides up at the back, or you can pull it more than a couple of inches from your spine, fix that first by going down a band and up a cup. The wire often stops poking once the band holds still.
The wire is too wide
Run a finger along the outer end of the wire. If there is a gap of empty cup between the wire and the edge of your breast, the wire extends beyond where your breast tissue ends. This means your breasts are narrower at the base than the cup assumes.
It commonly happens after going up a band size. Wires widen with the band, so a sister size on a bigger band can put the wire further back than you need. If you recently moved from, say, 32E to 34DD and the poking started then, go back. See do sister sizes really fit the same?
What to try
- Styles with narrower wires. Plunge bras usually have shorter, narrower wires than full-cup or balconette styles in the same size.
- Brands that cut for narrow, projected shapes. Wire width at a given size varies between brands.
- A smaller band with a larger cup, if the band is at all loose.
The wire is too tall
If the wire follows the edge of your breast correctly but its tip comes up too high at the side, it will dig in when your arm is down. This is a question of height, not size. It is most common if you are short in the torso or have a high-set bust, so there is less distance between the breast crease and the armpit.
What to try
- Plunge and demi styles, which have lower sides.
- Avoid full-cup and side-support styles with high side panels, at least in that brand.
- Non-wired bras, which remove the problem.
The cup is too big
If the cup has spare room all over as well, the wire is bigger than you need in every direction. Go down a cup on the same band.
Which is it?
| What you find | Cause | Try |
|---|---|---|
| Band rides up or shifts | Loose band | Band down, cup up |
| Empty cup at the outer edge | Wire too wide | Narrower-wired style |
| Cup fits, tip of wire too high | Wire too tall | Plunge or lower-sided style |
| Cup loose everywhere | Cup too big | Cup down |
Wire width and height relate to the outline of the breast where it meets the chest. That is explained in what a breast root is, and it is the most useful thing to understand if wires have never felt right on you.
Frequently asked questions
Why does my underwire poke me under the arm?
The wire is too wide or too tall for your frame, or the band is loose enough to let the wire travel. Shorter and narrower torsos are affected most.
Should I go down a cup size if the wire pokes my armpit?
Only if the cup is also loose. If the cup fits in volume, going down will make you spill. A style with narrower wires or lower sides in the same size is the better answer.
Can I bend the wire to make it fit?
It is not a good idea. Wires are tempered to hold a curve, and bending one usually creates a pressure point or breaks it through the casing.
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