D Cups: Breast Size Comparison
Do you think you know what a D cup looks like? If you ask around, chances are that most people will assume it’s big – very big, even. So you may be shocked to know that in the grand scheme of things, a D cup is actually on the smaller side. For starters, just the average cup size in America is an already-larger DD to DDD!
So why is it that we’ve come to think of D cups boobs as being huge? How big are they really? And what’s difference between a D and DD cup size? We’ll explain it all in this article.
How big are D cup size boobs?
A ‘D cup’ isn’t actually any specific size, at least not when the letter is used on its own. What do we mean by this? That people wearing a 32D, a 36D, and a 40D would all have very differently-sized breasts. To understand why, you first need to understand how bra sizes are calculated.
A bra size includes a number and a letter. The number indicates how big the ribcage is, i.e. how long the bra’s band needs to be to wrap around the body. The letter is the only part that indicates how big or small the breasts are, and each letter through the alphabet represents a 1” difference between the ribcage (underbust) measurement and the measurement around the breasts (overbust). So a 1” difference would be an A cup, a 2” difference would be a b cup, and so on.
Therefore, being a D cup simply means that your breasts stick out 4” from your ribcage. However, on a larger body they will be wider – and hence larger overall. ‘D cup’ boobs come in lots of different sizes.
That’s why one person’s D cup size can end up being the same overall size as someone else’s B cup size. Imagine you’re a 32D. A 34D has cups that stick out the same distance
but are wider, so hold more volume overall. They’d be too big for you, so to wear a 34 band you’d need a smaller cup size – a 34C. And if you went up a band size again to a 36, those 36C cups would again be bigger than the 34C ones, so you’d need to size down to a 36B.
Now, that band would likely be much too loose for you. But it shows that two women wearing a 32D and 36B would have differently-sized bodies, but same-sized breasts. These are what is known as sister sizes, and we’ve explained them in more detail at the end of our bra size calculation page.
In fact, many women are sister sizing into a larger band and smaller cup size without even realizing it. A research study by the University of Portsmouth found that 76% of women overestimate their band size, while 85% underestimate their cup size.
If the smaller band size and/or larger cup size you really need are hard to find in stores, you may never have had a chance to try them on – or even know that they exist! Plus, many people haven’t been educated on how a bra should fit, so may not realize that the one they think fits fine in fact doesn’t.
So while you’re on our bra size calculator page, take a moment to plug in your measurements and find out your recommended size. You may be surprised to learn that you should be wearing a D cup or above!
Why is a D cup thought of as being big?
As the bra size calculator linked above shows, bras come in a huge range of cup sizes – all the way up to an L cup, and beyond! So why does society in general think of a D, a letter that’s relatively close to the start of the alphabet, as being so large?
It’s all to do with the availability of those larger cup sizes. When cup sizing was first invented by the brand Formfit, there were only three choices – Small, Medium, and Full Size. Later, the brand S.H. Camp and Company began offering bras in four sizes and decided to name them A-D. The letter-based system caught on, but for a long while, most brands never went beyond four sizes.
In the 1950s, when cone bras were in vogue and having a full bust became seen as more desirable, brands slowly introduced more sizes. However, perhaps because brands never expected to have more than 5 cup sizes, or perhaps because there was still some stigma attached to having large breasts and therefore a good many people who would have disliked being told they were anything larger than a D cup, this next size up after D came to be known as DD.
Today though, despite DD and many more larger cup sizes now existing, A-D still persist as the most common ones. In fact, at major lingerie chain stores and department stores in the US, you’ll struggle to find much (or even anything!) above a D or DD.
That makes most consumers believe that those are still the only sizes being made – because if very few places are selling F cups, that must mean that people needing an F cup size are extremely rare, right? Those must be huge? But it’s not true. It’s just the inevitable result of the US lingerie industry having been dominated for decades by a certain well-known brand that was slow to expand beyond a D cup.
D cup vs. DD cup – what’s the difference?
In sizing terms, the difference between D and Double D boobs is not all that much. As explained above, DD boobs simply stick out 1” further than D ones, so assuming they are both on the same band size (e.g. 32D and 32DD) the DD ones would be slightly bigger. It’s exactly the same size difference as for a B cup vs. C cup, or a C cup vs. D cup.
However, when it comes to bra construction, you can actually find quite a few differences between bras made for D and DD boobs. That’s because DD is where ‘full bust’ sizing starts. Even on a small band size, DD boobs are big enough that they tend to need a little more support than, say, C cup boobs.
Hence, a double d bra and other DD+ sizes often have specific design features that are there to boost support. For example, seamed cups, a taller band, wider straps, and side panels or ‘side slings’ inside the bra. All of these help the bra to better lift and shape a large bust, or simply feel more comfortable on one.
Even the same bra can actually be designed slightly different for different breast sizes – next time you’re in a boutique and see a bra that comes in both A-D and full-bust sizes, take a look for yourself and see if you can spot any of these construction tweaks!
What bra size comes after DD – DDD, E or F?
As we’ve mentioned, you can find bra sizes all the way up to an L cup – and higher, at some specialist retailers. So just how do you get there? What comes next after a DD cup?
Well, it actually depends on where in the world you are. In mainland Europe, DD doesn’t actually exist. The cup sizes simply continue straight through the alphabet – A, B, C, D, E, F, and so on.
In the US, some brands adopted the European way of doing things, whereas others simply added another D every time they launched a new size. In other words, their sizes go D, DD, DDD, etc. So among US brands, a DD and E cup are the same thing, DDD and F cup are the same thing, and DDDD and G cup are the same thing.
However, just to add to the confusion, the UK has a whole other cup sizing system! There, from a D cup onwards, you also get a ‘double’ version before moving onto the next letter – except for the E cup, for some reason. So the sizes run D, DD, E, F, FF, G, GG, H, HH and so on. Also note that in the UK, there’s no such thing as an I cup – they skip this letter because it looks too much like a number 1.
If you’re full-busted and buying bras from a foreign brand or retailer, it’s easy to accidentally order what you think is your cup size, and it turn out to be wildly different. So be sure to check our international bra size conversion chart and make a note of what your bra size is equivalent to in different countries!
So how big are DDD and DDDD breasts?
In the UK, the cup sizes DDD and DDDD are called E and F, but are slightly bigger than a US E and F. In Europe, these sizes are called F and G, and are equivalent to US F and G sizes. If you’re confused, check out the international size chart linked above which should make things clear.
But how big is a DDD bra size in practical terms, and a DDDD? Well, triple D breasts are one cup size larger than double D breasts, and a DDDD cup is one size larger still (so two sizes beyond a DD).
Coming back to the fact that each cup size represents a 1” difference between the ribcage and overbust circumferences, someone with DDD breasts has a 6” difference, and someone who is a DDDD has a 7” difference. These are both full-bust sizes for sure, so they’re never going to look very small.
However, we’ve also explained further up why one person’s D cup can be much larger or smaller than another person’s D cup. Of course, the same is true for triple D boobs and quadruple D boobs. DDDD boobs will always be one size larger than DDDs on the same band size. Here’s a comparison of 32DDD (left) and 32DDDD (right) breasts:
However, 40DDD breasts would be significantly larger than 30DDD breasts. And 40DDD breasts would be the same size as 38DDDD breasts, because these are sister sizes. In fact, on a 32 band size, you’d need to wear a DDDDDDD cup to have the same breast volume as a 40DDD!
So the answer to how large DDD and DDDD breasts are is best summarized as “big, but you need to know the band size to determine just how big”.