How Big Are A, AA, and AAA Cup Breasts?

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The A-cup bra generally is considered the smallest bra size available. AA and AAA sizes do exist, but they are fairly difficult to find. Having a small chest offers you several perks. You can get away with going braless and you can also wear any style of bra or top that you want, with no issues. In the article below, I discuss exactly how big an A cup really is.

How Big Is an A Cup?

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

A cup size usually has a band size of 34 to 36 inches and underbust may range from 26 to 31 inches

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 of your bra.

Women who have A cups with a smaller band size (28-32 inches) will appear to have a slightly larger chest than women with larger band sizes because A cups look bigger on petite frames compared to wider frames.

What Is the Difference Between A and AA Cup Sizes?

The next size up from the A cup is the B cup bra size. An AA cup is a size smaller than an A cup and a AAA is smaller than AA.

AA and AAA sizes are rare and most lingerie brands do not manufacture bra sizes below an A cup. People whose size falls within this category should look for brands that specialize in small-bust size bras.

What Is a Small Bra Size?

A small bra size includes the cup sizes A, AA, AAA and B.

Small sizes from A to AAA can have up to a one-inch difference between the band and bust measurements. A B cup has a bust measurement two inches larger than the band measurement.

Comparing A, AA, and AAA Cup Sizes

Cup Size Underbust Overbust
A 22 to 62 inches26 to 65 inches
AA 22 to 62 inches22 to 64 inches
AAA 22 to 62 inches20 to 63 inches
Woman wearing a black bra

What Bras are Best for A Cups?

For most women with A-cup breasts, 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 smaller breasts, you should avoid horizontal seams since they add depth to your bra cup.

Smaller breasts are usually shallow and in most cases will not fill a deep cup, and as a result, the fabric of the cup will appear wrinkled.

You should also avoid tall or full cup bras that come up high on the décolletage as your smaller breasts tend to be shallower on the top and will not fill out the cup 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 your A 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.

For women with really small breasts, like A cups, I recommend having an awesome push up bra. Here’s one with serious lift – the FallSweet Add Two Cups Bras Brassiere. You’ll get some serious cleavage for a night out on the town (no joke).

Related Questions

How Will I Know if I Have an A, AA, or AAA Cup Size?

Calculate the difference between your underbust and overbust to determine your cup size, then compare it to the A, AA, and AAA sizes on a brand’s size chart. You may also consider them as sister sizes from time to time.

Is an a Cup the Smallest You Can Purchase?

No, an A cup is not the smallest size available. Some brands offer AA or AAA as the smallest cups for their bras.

Are A, AA, and AAA Cups Normal Sizes?

Yes, A, AA, and AAA cups are standard bra sizes. These are among the smallest sizes available.

Bra Size Measurement & Cup Size | A, B, C, D, DD Bra Sizes AND Extra Large Breasts


There are many women who have smaller breasts, even though boobs seem to get bigger and bigger if you listen to the media. Although many brands manufacture A cup bras, most women with A cups struggle to find a well-fitting bra. Don’t despair, with the right bra brand and styles designed for a smaller bust, you will definitely find bras that will fit you perfectly.


Allena is the Founder and Editor of The Better Fit, a platform dedicated to empowering women with practical advice on bras and fitness, inspired by her own revelation of the widespread issue of incorrect bra sizing. Her expertise and tips have been recognized by major publications such as Cosmopolitan, Better Homes & Gardens, Insider, and NBC, making her a trusted voice in women's wellness and lifestyle.