‘Why do my bra underwires hurt?’ and 'How do I stop my bra digging in' have to be two of the most common questions we get asked, and the truth is it can be due to a number of things so we’re going to break them down for you to help you figure out what’s going wrong with your bras! 

Before we get stuck in to why your bra's underwires might be hurting you, we’re going to answer what it actually is that bra underwires do! Underwired bras basically contain a semi-circle of metal that runs along your breast root, working with the wings (band) and cups of a bra to create a cantilever that helps to lift, support and separate your breasts.

Comparison band size affecting underwire bra fitThe correct band size allows the wire to sit neatly around the breast (left). A too-tight band size causes the wires to stretch too far into the armpit (middle). A too-loose band size causes the wire to press slightly on the breast tissue (right).

So, why do bras dig in and why do underwire bras cause pain? Honestly, the most common issue we come across is bad bra fit. All the components of a bra work together to help with finding the perfect fit, ensuring that the underwire perfectly encapsulates your breast tissue – and the fit issue we see the most is the band size being too loose.

With a bra band that’s too loose, it isn’t able to pull the wires open to fully encase your breast tissue, meaning that it sits on and pokes into your breast instead.

On the other hand, a band that’s too tight can cause the wires to press in painfully against your chest, pulling the wires open too far meaning they dig in at your underarm.

Cup too small affecting bra and underwire fitThe wire encases the breast tissue without digging in to the breast or armpit (left). The cup is too small, causing the underwire to sit on and dig into the breast tissue (right).

The next most common fit issue we see is a cup size that’s too small. This often comes hand-in-hand with a too-loose band, so it isn’t surprising that the wrong cup size can cause painful underwires too!

A too-small cup size means the wires won’t be wide or deep enough to contain your breast tissue comfortably.

Meanwhile, a cup size that’s too big can put excess pressure on your sternum where the wires come up too far and can also extend too far past your breast tissue into your armpit, causing pain there as well.

So how should a bra fit under the arm? The wire should sit just behind your breast tissue to hold it all in place, like in the left image below:

Woman wearing a black bra demonstrating different underwire positionsA well-fitted bra's underwire should follow your breast root (left). A cup that's too big can sit too high up under the armpit and dig in uncomfortably (right).

But what if your bra fits perfectly in terms of size, and you still find underwired bras painful? It may be down to the brand or style of the bra. Not all bras are made equal, and every brand will use different underwire shapes, widths and weights, meaning not every single one will work for everybody as our breast roots are all different shapes.

Try some different brands or styles to find something that works for you – for example if you find balconette bras cause too much pain and dig into your chest, try switching them out for a plunge bra which typically have shorter wires at the front.

A comparison of a balcony vs plunge bra underwire shapesBalconette bras have underwires which sit higher up on the sternum (right). Plunge bras tend to have a much lower centre gore, so the wires sit further down the sternum (left).

We all love that feeling of taking our bra off at the end of the day, but if you’re counting down the hours because you’re in so much pain from the wires, it might be time for a bra intervention! Make sure you’ve had a recent bra fitting (we recommend being re-fitted every 6 months) or take our free and easy bra fit quiz.

When wearing a properly fitted bra (both size and shape), a bra's underwires should be barely noticeable and cause no discomfort or pain – unless you have a medical condition or experience chronic pain which can cause heightened sensitivity to things like bras and other tight-fitting garments.

If this is a struggle for you, we’ve got a whole host of supportive non-wired bras available, designed to offer gentle support and provide a comfortable fit.

I hope this has helped you understand what can cause discomfort with underwires, and how to combat it!

LJ x

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