What Do Bra Sizes Mean

Finding the perfect bra can feel overwhelming, with so many sizes, styles, and brands to choose from. The key is understanding what bra sizes really mean, the numbers, the letters, and how they work together to create the right fit. Once you know the basics, shopping for lingerie becomes easier, more comfortable, and more confidence-boosting.

At Maison SL, we have fitted thousands of women and know first-hand how much difference the right bra size can make. Below, we explain how bra sizes are calculated, bust some common myths, and share expert tips for finding your perfect fit.

How Do You Calculate Bra Size?

Measuring yourself at home is a good starting point, although we always recommend a professional fitting for the most accurate results.

1. 1. Measure your underbust (band size):
      Wrap a soft tape measure snugly around your ribcage, just beneath your bust. Round to the nearest whole number. If it is odd, add one inch. This is your band size.

   2. Measure your bust (cup size):
      While wearing a non-padded bra, measure around the fullest part of your bust, keeping the tape level.

   3. Work out the difference:
      Subtract your band measurement from your bust measurement. Each inch difference equals one cup size:

      • 1 inch = A cup

      • 2 inches = B cup

      • 3 inches = C cup

      • 4 inches = D cup

      • and so on.

Bra Sizes Explained

What Does The Number On A Bra Size Mean?

The number in your bra size (for example 34B) is your band size, which is the measurement around your ribcage. The band is what provides most of the support.

A common mistake is wearing a band that is too loose. If the band rides up your back, or if the straps are doing all the work, you likely need to go down a band size.

What Do The Letters Mean On A Bra Size?

The letter in your bra size represents your cup size, based on the difference between your bust and underbust measurements. Cup size is always relative to the band size.

That means a 36C has more cup volume than a 34C, even though they share the same cup letter.

• A: 1-inch difference
• B: 2-inch difference
• C: 3-inch difference
• D: 4-inch difference

...and so on. The combination of the band size and cup size (e.g., 34B) indicates your complete bra size.

Different countries may have different sizing systems for bras.

For instance, the UK, US, EU, and other regions may use slightly varying cup sizes or measuring units. Use our bra size conversion chart to help you if you're buying lingerie from different international brands.

International Bra Size Conversion Chart

BUST MINUS BAND	UK CUP SIZES	US CUP SIZES	EUROPEAN CUP SIZES
less than 1"	AA	AA	AA
1"	A	A	A
2"	B	B	B
3"	C	C	C
4"	D	D	D
5"	DD	DD/E	E
6"	E	DDD/F	F
7"	F	DDDD/G	G
8"	FF	H	H
9"	G	I	I
10"	GG	J	J
11"	H	K	K
12"	HH	L	L
13"	J	M	M
14"	JJ	N	N
15"	K	O	O

Why Are Bra Sizes So Confusing?

There are a few different reasons that contribute to the confusion that is bra sizing. One of the primary factors is that there is no universal sizing system across different brands and manufacturers. Each company may use different measurements or fit models, leading to inconsistencies in sizing.

A second reason is size conversion. Despite some brands trying to adhere to the same system of fit and proportion, different countries have their own unique sizing systems.

As a result, depending on where the brand is based, the size you typically wear may vary significantly. You might be a 32B in one brand in the UK, but then in Spain, you could be a completely different size.

The challenge with navigating this issue is not only finding your correct size within each brand's range but also being able to accurately convert between them when purchasing bras from international retailers or online stores.

This highlights how complex and nuanced bra sizes can often be – requiring both patience and persistence when shopping for lingerie that fits comfortably and flatters your figure perfectly.

Finally, another factor contributing to confusion around bra sizes is societal pressure surrounding body image.

Some individuals might feel ashamed or embarrassed if they do not fit into traditional beauty standards set by society, which often include having a certain bra size leading them to shy away from finding well-fitting bras and buying the same size for years on end even when their body has changed due to weight gain, childbirth or ageing.

Ultimately, it can be difficult to find the perfect bra fit which is why we always recommend heading to a lingerie expert like our founder, Susana Lorena. Here at Maison SL, we can find your perfect fit in a style that suits you. 

By educating yourself on proper measurement techniques and finding brands that work well with your unique shapes, you can alleviate some of the confusion surrounding bras.

What Are Sister Sizes In Bras?

Sister sizes refer to bra sizes that have the same cup volume but different band sizes. For example, a 34C and a 36B are sister sizes – both have the same cup volume but with different band sizes. This is helpful to know when trying on bras, as you may find that a sister size provides a more comfortable fit.

Common Myths and Misconceptions about Bra Sizes

Myth: A Bigger Cup Size Always Means Bigger Breasts

One of the most important aspects of finding the perfect fit is understanding that cup size is relative to band size.

To put it simply, a 34D and a 36D may both have the same "D" cup size but their overall volume will differ significantly due to differences in their respective band sizes. In essence, if you were to compare these two bras side by side, you would notice that the cups on the 36D appear much larger than those on the 34D.

Myth: Once You Know Your Bra Size, It Will Remain the Same Forever

Our bodies change over time due to various factors, such as weight fluctuations, hormonal changes, and ageing.

This means that your bra size may also change throughout your life. Regularly measuring yourself and getting professionally fitted can help ensure you're wearing the correct bra size.

Myth: All Bras In Your Size Should Fit You Perfectly

As mentioned earlier, different breast shapes may require different bra styles. Even if a bra is technically your size, it may not provide the best support or comfort due to your specific breast shape.

 

Final Words

A professional bra fitting can be immensely helpful in finding your perfect bra size. Good quality lingerie shops, like Maison SL in West London, should offer this service. A professional fitter can guide you through the process of measuring your size, recommend suitable styles for your breast shape, and help you find the right fit.

Understanding bra sizes and what they mean can make all the difference in finding a comfortable and supportive bra. By familiarising yourself with the basics of bra sizing, debunking common myths, and trying on various styles and brands, you'll be well on your way to discovering the perfect bra for you.

Remember that investing time and effort in finding the right bra size is an investment in your comfort, well-being, and confidence.