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How Big Is an A Cup?

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If you wear an A cup bra, you might have been self-conscious at one point or another about the small size of your chest. However, there are a lot of perks to having a small chest – you can wear most tops without showing too much cleavage, and your upper body can look more slender.

So, just how big is an A cup? In this article, we’ll cover details about an A cup size and recommend bras for your smaller chest.

How Big Is An A Cup?

An A cup means that your bust measurement is 1 inch bigger than your band size. A-sized cups are considered to be one of the smallest cup sizes, with only AA and AAA being smaller. 

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Woman with an A cup wearing a black bra

Keep in mind that not all A cup breasts look the same. While A cups are usually 1 inch bigger than the band size, the cup volume is still going to differ depending on the band size. Women who have A cups with a smaller band size (28-32 inches) will appear to have a slightly larger chest because A cups look bigger on petite frames compared to wider frames.

What is The Difference Between A and AA Cup Sizes?

Most people know that DD cups are bigger than a D cup size. However, when it comes to A cups there are exceptions. The next size up from the A cup is the B cup size. An AA cup is a size smaller than an A cup. Additionally, AAA is smaller than AA.

AA and AAA sizes are rare, and most renowned lingerie brands do not manufacture bra sizes below an A cup. This means that people who fall within these categories should look for specialist small-bust brands. The size difference between an A cup and an AA cup will largely depend on the brand.

What Is a Small Bra Size?

A small bra size typically has a band size of 34 to 36 inches, while the underbust may range from 26 to 31 inches. The smallest cup sizes include A, AA, AAA, and B.

Small sizes from A to AAA can have a one-inch difference between the band and bust. Meanwhile, a B cup has a bust size two inches higher than the rib band.

Woman wearing a black bra

What Bras are Best for A Cups?

For most women with A cup boobs, shopping for bras can be quite challenging. It can even be harder to shop for bras for AA cup sizes. When buying bras for your small breasts, you should avoid horizontal seams since they add depth to your bra cup. Small breasts are usually shallow and in most cases will not fill the deep cut, and as a result, the fabric will appear wrinkled.

You should also avoid tall cups or full cup bras that tend to come up high on the décolletage, these kind of bras are perfect for women with 34C cup sizes. This is because your small A breasts tend to be shallow on the top half and will not fill out the cup here, which will result in gaping. Instead, you should opt for these types of bras:

  • Push up bras: Every woman with an A cup needs a push up bra in their closet. This bra can instantly convert you to a B cup, and it’s perfect for date nights or clothing where you need a little extra oomph.
  • Balconette or demi bras: Demi and balconette bras lift your boobs up while providing a bit of cleavage. Similar to a push up bra, these styles also help to make your chest appear slightly bigger than it is.


In the mainstream media, breasts seem to get bigger over time. However, there are many women who have smaller breasts. Although many brands manufacturer A cup bras, most women with this breast size struggle to get a bra that fits perfectly.

This is because most of them have a shallow breast shape that makes bras wrinkle or gape. But with the right bra brands and styles designed for this boob shape, you will definitely find A cup bras that will fit like a glove.


Hi there, I’m Allena, Founder and Editor of The Better Fit. I’ve always had a passion for finding ways to help women improve various areas of their lives. I have researched and worked to create this website so women would have a place to come and be informed about an article of clothing they literally wear every day.