Are You Wearing the Wrong Bra Size? Here’s How to Find Your Perfect Fit

Bra fitting

Balcony, t-shirt, bandeau, strapless, halter, lace, padded, underwired, plunge….there may be many different bra styles and designs, but there is only one essential rule to remember: make sure it fits! Yes, I know, that seems really obvious, but did you know that most of us are wearing the wrong bra size? We teamed up with Marks & Spencer to find out what the perfect fit really means, and what to look out for when shopping for your next bra.

Whether you are an A cup or a G cup, the right bra is an essential part of your outfit, not something that gets forgotten because it may not be seen. If we go clothes shopping, we’ll try on numerous options before selecting what makes us feel great – so why aren’t we doing that with bras?

Don’t waste your money guessing your bra size, or sticking with the size you’ve worn for the past 10 years. Measuring is the only way you’ll know your true size, and we recommend the Bra Fit service at Marks & Spencer for getting accurate advice. The appointments are free (just book online or in-store), so there’s no excuse to get in and get measured!

Let’s take a look at some of the most common mistakes we make when buying a bra, and how to ensure you’re getting the best fit for your assets!

Finding the Perfect Fit

There are two important measurements that you will need before shopping for the perfect bra – your back size and your cup size. The back size is the number on the label (e.g. 32, 36 or 40), while the cup size is the letter (e.g. A, B, DD, F). Both need to be right so that you – and your breasts – are as comfortable as possible.

If you’re not sure what a ‘good fit’ means, these are some good rules to follow:

  1. The band that runs under the breasts and around your back should be snug, but not so tight it digs in to your skin. There should be enough room to fit two fingers underneath.
  2. If you are wearing an underwired bra, the wires should sit flat against your chest. Go up a back size if the wires are digging into your breasts or if the wires are raised away from your breastbone.
  3. The cup of the bra should mould to your skin and be flush with your breasts. There should be no gaping space (cups too big) and no spilling over the top of the cups or under the arms (cups too small).
  4. The bra straps should not be falling down or digging in to your skin. The right bra will have most of the support coming from the underband, so the straps should be able to be loosened without affecting the fit of the bra.

Changing Shapes and Bra Size

are you wearing the right bra size - Mykidstime

Our bodies change all the time as a result of hormonal changes, pregnancy, nursing, weight fluctuations, surgery and more. And while we may buy clothing in a different size, how many of us take the time to go and get re-measured for the right bra size? Guilty as charged here, I admit it!

Holding on to bras that no longer fit just because they are pretty or expensive or sexy is the same as keeping those jeans we all hope to fit back in some day…it’s time to claim back control and love the body you’re in now. This body deserves clothes and bras that fit, that compliment your shape, and that leave you feeling strong and confident.

Larger Busts

If you are a D cup or larger, you may find it harder to find comfortable, stylish, affordable lingerie – and, let’s face it, we want the same frilly, pretty, lacy bras everyone else gets to choose from!

This is why we love M&S because the standard range goes all the way to an E cup, but there is also a gorgeous DD+ range that goes to a H cup in selected styles. With lots of colours and styles to choose from, there is definitely no compromising style over support.

Maternity and Nursing

Oh I remember how daunting this was! As a dedicated underwire girl, it was a shock to the system to know that these aren’t recommended from early pregnancy – the wires can be restrictive and uncomfortable for fast-growing breasts, and can potentially restrict milk ducts. But don’t panic, there are still plenty to choose from!

Maternity bras have come a long way, and there are lots of pretty, functional and supportive bras to choose from – but remember that your shape and size will continue to change in the coming months. By the third trimester, most pregnant women are two back sizes and four cup sizes bigger than their pre-pregnancy size!

If you are a nursing mama, or soon will be, we love the range from Marks & Spencer because every bra has drop-down cups that make breastfeeding easier, plus the clips are simple to do one-handed and the stretch in the material is very accommodating for changing breast sizes.


If you have recently had breast surgery, you may have sensitive scar tissue, swelling and tenderness around the breasts, so a well-fitted bra is important. We were thrilled to see that M&S has worked with the charity Breast Cancer Now to create a post-surgery range of bras. You won’t need to sacrifice on style as the bras are pretty AND comfortable – plus, better still, M&S will donate 10% from every product in the range to Breast Cancer Now to support research into breast cancer.

The range includes supported prosthesis pockets in both cups with easy opening, as well as soft cotton designed not to rub, fabric to keep you cool, and smooth microfibre straps and trimmings to be as sensitive as possible.

Smoother Lines

If VBL (visible bra line) drives you crazy and you can’t abide the feeling of labels, seams and stitches, the Smoothlines range from M&S is perfect. Extra-thin cups, ultra-fine edges and a unique lace design helps create a smoothing effect under your clothes.

M&S smoothlines bra

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What Bras Do You Need?

Now that you know what size you are, you may need to reconsider your lingerie collection. There are 4 bras every woman needs – and anything after that is a bonus!

  1. A good sports bra is essential as it supports and protects the delicate breast tissue. A sports bra will prevent your breasts from moving around, minimising ‘bounce’ and reducing the chance of friction and irritation that wearing a normal bra might cause.
  2. A strapless bra is always useful and can be worn under cami tops, as well as strapless tops and dresses.
  3. A t-shirt bra for smooth lines, a seamless silhouette and great everyday comfort.
  4. A white, nude or neutral bra so you don’t get caught out when wearing a light coloured top (personal experience!)

When you’ve got yourself kitted out, it’s time to say goodbye to your old bras that are the wrong size by donating them – M&S can help with this too, thanks to Shwopping.

Just bring your unwanted clothes (even if they’re not from M&S) and put them into a ‘Shwop Drop’ box by the tills in most M&S stores. All clothing goes to Oxfam and they’ll either resell it in one of their shops or on the Oxfam Online Shop, sell it to be reused in different countries around the world, or recycle the fibres to make new material (which can be used by businesses like M&S, for example, as mattress filling). Absolutely nothing goes to landfill and Oxfam will use the money raised to help end extreme poverty around the world.

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Have you been measured for your correct bra size? Do you need a bra revamp? Leave a comment below and let us know – we’d love to hear from you!


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