A cup vs B cup – The difference between these bra cups

This article contains (Amazon) affiliate links, see my full disclosure at the bottom of the page.

An A cup and a B cup bra can have the same cup volume. How come? Well, you cannot judge a bra size only by its cup size. So, how do they differ?

woman wearing lace pus up bra illustrating article on a cup vs b cup

Maidenform Smoothing Lace-Trim Bra with Push-Up Cups | See Amazon.com

See my bra calculator or shop for bras at:

Lulalu Bras | Women's AAA-A cups »

HerRoom | Training and teen bras »

ThirdLove | Asymmetric Breasts »

Topics »

What is the difference between an A cup and a B cup?

Dobreva Floral Lace Everyday Lightly Padded Underwire Bra | A – DD cups | See Dobreva at Amazon.com

It’s a question I get a lot from my readers. What’s the real difference between an A cup and a B cup?

Lulalu offers a wonderful collection of bras for women with AAA, AA, A cups | bands 30-42 | See Lulalu.com

And I’m happy they’re asking. Why? Because if you know the answer to this question you really know all there is to know about bra sizing.

It is very understandable for any woman not to wear a well-fitted bra. Bra sizes can be very close together. The same woman might actually fit more than one bra size. And all these bra sizes may fit her just fine!

So, it may seem cup B is bigger than cup A. But as it comes to bra sizing it’s just not that simple.

Is B cup bigger than A cup?

To compare different cup sizes you would have to know your band size too. Tips for measuring your band size

A cup vs B cup could mean:

Instead of the 75A bra, you’re wearing right now
you might need a 75AA, a 70B, an 80AA, or an 80AAA bra

Really?

Yes. It’s all about the fact that bra sizes can be this close together. A little change in measurements could mean you need a totally new bra size.

There’s also the possibility you might need your bra sister size.

Do you only want to change your band size? It’s your bra sister size you’re looking for.

For example, your bra size is 38C. The bras 36D and 40B all have the same cup volume. These are called your sister sizes

How will I know if I’m an A cup or B cup?

Lily of France Extreme Ego Boost Push-Up Bra A-D cups | See Amazon.com

I’ve listed some points for you to score yourself.

✔ take a good look at your bra in the mirror
✔ does it really look good?
✔ does it feel comfortable?
✔ does its elastics fiber support your breast firmly, but still in a comfortable way?
✔ do you feel your bra the whole day? Not in a nice way…
✔ are you touching your bra a lot during the day (to keep it in place)?
✔ will the bra make your clothes stand out?
✔ do you feel confident wearing your bra?
✔ do you feel womanly?
✔ have your breasts changed after breastfeeding?
✔ have you gained or lost weight?

It could be the elastic fibers of your bra are not strong anymore. So maybe your bra size is still correct, but your bra(s) need to be replaced. Read more on how to handwash your bras

Handful Women’s Y-Back Maximum Support Racerback Sports Bra with Removable Pads AAA-D | See Amazon.com

When I measure women and tell some of them they should be wearing another bra size they are never surprised!

Why?

Because we see ourselves every day in the mirror and we feel our bra all day long. Changing your bra size when needed isn’t something we act upon easily (happened to me). Especially if you wore this size for a long time.

Maybe someone else advised this size on you (and you think they would know…).

If you have small breasts be sure to check as size chart that includes all small sizes
or use my bra size calculator. And please play around with the measurements a bit. This will show you whether you might fit more than one bra size. Depending on the model and brand you’ll know the alternatives you have. In the end, you’ll know which size feels best for you.

What is the difference between an A cup and a B cup?

Is B cup bigger than A cup?

How will I know if I’m an A cup or B cup?

Other articles you might like