Why Underwire Digs In
An underwire that digs in is almost always sitting on breast tissue instead of on your ribcage. That means the cup is too small or the wire too narrow. Go up a cup at the same band first.
An underwire that digs in is almost always sitting on breast tissue instead of on your ribcage. That means the cup is too small or the wire too narrow. Go up a cup at the same band first.
Where a wire is supposed to sit
The wire should rest entirely on your ribcage, following the crease where breast tissue meets your body – the “root” – and finish flat behind the breast near the underarm. It should never cross tissue. If you can feel it pressing on soft tissue anywhere along its length, it is in the wrong place.
The four things that put it in the wrong place
| Where it digs | Usual cause | Try |
|---|---|---|
| Underarm / side | Wire too narrow for your root | A wider-wire style; up one cup |
| Front, on tissue | Cup too small | Up one cup, same band |
| Centre, at the sternum | Cup too small, panel not sitting flat | Up one cup; a plunge style if it persists |
| Underneath, into the ribs | Band too tight, or wire too long | Up one band, down one cup |
Start with the cup
Go up one cup and keep the band. A larger cup has a longer, wider wire, which is usually exactly what is needed. If two steps up does not solve it, the wire shape is wrong for your breast root rather than the size being wrong – a different brand or a different cut is the answer.
A wire that pokes through
A wire that has broken out of its casing is not a fit problem; it is a worn-out bra. It usually happens at the underarm because that is where the wire flexes most. Stop wearing it – a poking wire can break skin. If it happens repeatedly and quickly in new bras, the cup is likely too small and the wire is under constant strain.
If wires never work for you
Some people never get on with wires, and modern wire-free construction supports far better than it used to, particularly bonded and moulded designs. Size the same way – band from underbust, cup from the difference – and expect to size the band down one step in some soft, very stretchy styles.
One note on pain
Ordinary underwire discomfort is a fit problem. Persistent localised pain, a lump, skin changes, or discomfort that does not resolve when you take the bra off are not sizing questions and this site cannot help with them – talk to a GP.