What is...
an Underwired Bra?

The world of bras and lingerie can be complicated, and you’ve probably come across the term ‘underwired bra’ before – but what is an underwired bra, what do they do and who needs one? Read on to find out all about bra underwires!

What is a bra’s underwire?

The underwire in a bra is a piece of metal or sturdy plastic that is curved, anywhere from a U-shape like in full cup bras to a J-shape more commonly seen in plunge bras, to fit around your breast under the bra cups.

What does an underwired bra do?

A bra’s underwires are designed to lift, shape and support your bust. An underwire gives more structure to the bra, to ensure a defined and sturdy cup shape.

Underwired bras work by gathering your breast tissue and holding it in place (remember you should scoop and swoop so your breast tissue is clear of the underwires), which in turn gives lift and shape to your bust.

The underwire of a bra acts as a cantilever with the rest of the bra to give support, working in tandem with a firm underband to lift your boobs up from underneath and allow the fabric of the cup to support more weight, giving that uplifted shape and perfect support.


"Extremely comfortable and just great. It's nearly like I'm wearing no bra but still have the support I need!"

Flirtelle Swirl Balcony Bra

Who can wear an underwired bra?

Underwired bras can typically be worn by anyone who wants to wear one – but they may need to be avoided for a period of time following surgeries like mastectomies or breast augmentation. It is always best to check in with your doctor or surgeon regarding that.

Bras with underwires are especially great for those with heavier and larger breasts as they do offer more support than a non-wired bra, but those with smaller chests can definitely wear and benefit from the support given by an underwired bra too.

Many people ask if they can wear an underwired bra throughout pregnancy and breastfeeding, and the answer is yes! While a lot of people find non-wired maternity and nursing bras to be more comfortable, there is no harm in continuing to wear underwired styles as long as you make sure they fit properly with the wires completely clear of your breast tissue so they don’t cause any damage.

If you tend to find underwired bras are uncomfortable, we’d recommend first of all checking your size with our bra fit quiz, or getting a proper fitting to make sure you’re in the right bra size. Underwires aren’t meant to be uncomfortable, and when you’re in the right size bra any discomfort should be greatly reduced. You may also need to experiment with different brands and shapes of bra to find one that feels right for you – every brand and style is made differently. Check out our blog on why bra underwires hurt for more info on this topic.

What are the benefits of an underwired bra?

To sum it all up, here are the key things to remember about underwired bras:

  • An underwired bra offers the most support, ideal for heavier and larger breasts
  • Underwires lift from below to reduce the strain on your shoulders
  • Bras with underwire give a more upfront, projected shape to your boobs

And there it is! We hope this run-through of what a bra underwire is and what underwires do has been helpful to you.

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