b cup breasts

B Cup Breasts: Size, Pictures, Implants, & Bras

How Big are B Cup Size Boobs?

There was once a time when 34B was the average bra size in the USA. In fact, right from the invention of cup sizes, a ‘B’ was considered average. That’s because the very first cup-sized bras only came in three sizes – Small, Medium and Full Size, later to be known as A to C. So if your breasts were neither small nor big, they were a B.

However, the lingerie industry has come on a long way since those early days of cup-sized bras. And with a B cup (or even C cup) now being the upper size offered by many small-bust specialist brands, can we still call B cup breasts pretty average? Or are they simply considered small?

The answer is not as clear cut as you might imagine. How big a B cup is actually depends on the band size it’s attached to. Read on to find out more.

What does ‘B cup’ mean?

A B cup size means that you have a 2” difference between your underbust (ribcage) and overbust (around the nipples) measurements. Similarly:

  • A 1” difference would be an A cup
  • A 3” difference would be a C cup.

This means that how big B cup boobs really are is relative to the band (ribcage) size. Someone who is a 38B will have larger breasts that someone who is a 32B, because although their breasts stick out the same distance, they will be wider. 

So the ‘B cup’ label – or any cup size – is really more about shape than size. About how far your breasts protrude, rather than the total amount of breast tissue there. Your B cup breasts could have the same amount of tissue as someone else’s A, C or D cup! If you’d like to find out more about why this is then we suggest reading the Bra Sister Sizes section of our bra sizing help page.

Lingerie brand Third Love advises that “any cup with a 34 band size is considered a “true cup” size”. In other words, that a true B cup is the breast size of someone who wears a 34B. However, as they appear to be the only brand making this statement, take it with a pinch of salt! At the end of the day, if you wear a 40B you still have a B cup size for all practical, bra-shopping purposes.

What does a B cup look like?

Given that B cup breasts are not all equal sizes, the best way to understand what they look like is to view some real examples on different band sizes. 

In the bra size pictures for B cup below, you can see that the amount the breasts stick out from the body doesn’t change all that much. And yet, the breasts clearly get larger overall as the band size increases.

B cup breasts examples (bra size pictures):

b cup breast example side view
b cup breasts side view
b cup breast example front view
Left to right: 30B, 34B, 38B
Images via Bratabase

B cup bra sizes and comparisons

A B is a common cup size, and hence you will find it readily available on many band sizes. Here is a list of B-cup bra sizes from smallest to largest: 26B, 28B, 30B, 32B, 34B, 36B, 38B, 40B, 42B, 44B, 46B, 48B, 50B.

B cup vs. C cup

B → C is one cup size larger so, assuming the band size is the same, the C cup breasts will stick out 1” more.

B cup vs. D cup

B → D is two cup sizes larger so, assuming the band size is the same, the D cup breasts will stick out 2” more.

A cup vs. B cup

B → A is one cup size smaller so, assuming the band size is the same, the A cup breasts will stick out 1” less.

How much do B cup breasts weigh?

Once again, the answer to this is: it varies! B cup breasts on a smaller band size will weigh less than B cup breasts on a larger one.

According to various online articles, a B cup weighs the same as:

  • 1 pair of heels
  • 2 hamsters
  • 5 cockatiels
  • 15 pancakes
  • 23 sushi rolls
  • 11,200 bees

Yes, that last one is very surprising! Then again, a bee only weighs one tenth of a gram. That would put each B cup breast at around 560g. But as explained, B cup breasts on larger band sizes are wider and hence will weigh more.

Perhaps the breast weight guide you can find online that’s most likely to be accurate is this one. It illustrates the bra sister sizing that we mentioned earlier, showing that a 30B chest weighs the same as a 32A or 28C one. According to this chart:

  • One 30B breast weighs 0.5lb (~227g)
  • One 32B breast weighs 0.6lb (~272g)
  • One 34B breast weighs 0.7lb (~318g)
  • One 36B breast weighs 0.9lb (~408g)
  • One 38B breast weighs 1.2lb (~544g)
  • One 40B breast weighs 1.5lb (~680g)
  • One 42B breast weighs 1.7lb (~771g)
  • One 44B breast weighs 2lb (~907g)

So carrying around a 30B chest won’t put much strain on your muscles, but carrying around a 44B one is not far off from strapping two bags of sugar to your chest! You don’t need to have a D+ cup size to have heavy breasts.

How big are B cup breast implants?

b cup breast implants

This is a trick question, because there’s no such thing as a ‘size B cup’ breast implant. There are three reasons for that:

  1. Implants are sized by volume

Breast implants simply aren’t categorized via a letter-based system, like cup sizes are. Instead, implants are sized by volume, measured in CCs (cubic centimeters). They range from around 80cc up to around 1,200cc.

  1. Bigger breasts need more adding to go up one cup size

If you take another look at the list of B cup weights above, you’ll notice that the weight increases aren’t evenly distributed. For example, going from a 30B to a 32B adds 0.1lb in weight, while going from a 42B to a 44B adds 0.3lb in weight.

Since breasts on larger band sizes are wider, you need wider implants for them which will weigh more / have a higher volume. Widths for breast implants range from 7.4cm through to 17.2cm. It’s therefore impossible to have a single implant size that makes any person go up by exactly one cup size.

  1. Bra sizing varies

Just as you may wear a Medium t-shirt from one brand and a Large from another, so too do lingerie brands have slightly different fits. Someone who usually wears a 32B will get their best fit in a 32A or 32C in a handful of brands. So no plastic surgeon can guarantee you’ll end up being a perfect ‘B size cup’, because no one wears the same cup size in every single bra band. 

So I can’t get B cup implants?

Not exactly. But if you want to increase your cup size to a B specifically, your plastic surgeon will be able to advise on the right size and shape of implant for your body to make that happen. In most bras anyway!

In the meantime, you can add gel bra inserts (the type sold to give you a little boost in the cleavage department) to a B-cup bra until you fill out the cups. Wearing them all day will give you a rough idea not just of how big your new breasts will look under clothes, but also how much they’ll weigh.

The Best B Cup Bras

b cup bras
The Natori Feathers bra, a regular feature on ‘best of’ bra lists and available in 30-38B

If you’re shopping for a B cup bra, then you’re in luck! This is one ofthe most commonly-produced cup sizes, so you have your choice of pretty much any brand – except, of course, for those specialized in full-bust sizing. Therefore, this list of the best B cup bras is really just a list of some of the bestselling bras out there, full stop.

Best push-up bra for a B cup

Comfort Devotion Bra by Maidenform – available as a B cup in 34-42 band sizes

Bombshell Add-2-Cup Push-Up Bra by Victoria’s Secret – available as a B cup in 30-36 band sizes

Full Effect Push-Up Bra by Wonderbra – available as a B cup in 32-38 band sizes

Sexy Lace Extreme Boost Bra by Ann Summers – available as a B cup in 30-36 band sizes

Best strapless bra for a B cup

Ultimate Strapless Bra by Wonderbra – available as a B cup in 32-36 band sizes

24/7™ Classic Strapless Bra by Third Love – available as a B cup in 32-48 band sizes

Halo Convertible Underwire Bra by Wacoal – available as a B cup in 32-38 band sizes

Feathers Strapless Bra by Natori – available as a B cup in 32-36 band sizes

Best everyday bra for a B cup

Feathers Bra by Natori – available as a B cup in 30-38 band sizes

Juliette Lace T-Shirt Bra by Figleaves – available as a B cup in 30-38 band sizes

Caresse 3D Plunge Bra by Simone Pérèle – available as a B cup in 32-40 band sizes

Sumptuously Soft™ Full-Cup T-Shirt Bra by Marks and Spencer – available as a B cup in 30-42 band sizes

Conclusion

B cup wearers are a lucky bunch. The number of bras available in this cup size is simply enormous, meaning you really have your pick of what you want. Plunges, demis, strapless bras… they’re all easy peasy to find in a B cup. It’s one of the cheapest sizes to manufacture too – common enough to make bulk manufacturing possible, and without the complexity of designing to support a DD+ bust. So you’ll find B cup bras at every price range, including the lowest.

Do remember though that B cup breasts vary in size. You can’t just grab any B cup bra off the rack and expect it to fit – a 36B’s cups are rather roomier than those on a 32B! That’s why it’s important to know not just your cup size but your band size too. Take a look at our bra size chart to discover your full size now.

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