The volume of the letter is entirely dependent on the band size it is paired with. A 38DD will be one cup size larger than a 36DD, which is in turn one cup size larger than a 34DD, for example.
Is D or DD cup bigger? There's no difference in the spacing between single and double letter sizes, a DD is one full size larger than D, just like E is one full size larger than DD.
Sizing. The 38DD is 1 band bigger than the 36DDD. The 38DD is 1 cup smaller than the 36DDD.
The 36DD and the 38D are the same cup size, the only difference is the 38 band is bigger around then the 36 band.
The band is pretty much the same in both bras. The 36DD bra has wider cups but they are both about the same depth.
For less than one inch you are a AA cup, for one inch you are an A cup, for two inches you are a B cup, for three inches you are C cup, for four inches you are a D cup and for five inches you are a DD cup.
Sizing. The 38DD is 1 cup bigger than the 38D.
Simply put, the difference between a D cup and a DD cup is that; a D cup is larger than an A, B or C cup and slightly smaller than an E cup. On the other hand, a DD cup is slightly larger than an E cup, yet still smaller than an F cup.
What about DDD and G cup sizes? In American bra size, A DDD cup is also called an F cup, which sits just one size above a G cup. It means that they differ by just one inch.
For example a 36C, 34D and 32DD are all the same cup size, but a 34D breasts project out 1 inch less than a 32DD but because the different from the band to the cup has increased they are both the same cup size.
All you need to do is a little bra math: Subtract your band size from your bust measurement to find your cup size. “The difference in inches corresponds to your cup size,” says Iserlis. For example, if your bust measures 37 inches, and your band size is 34, the difference will be 3.
Fast Fact: What is with the size DD? Before the days of Kim Kardashian, Sofia Vergara and Amber Rose, women had a thing about not wanting to appear 'too big'…and manufacturers realised they would sell more bras sized as DD rather than E, because alas, it sounds 'smaller'.
The answer is no. The idea that all cups of the same letter are the same size is a myth. Pretend you're a 34D. The “34” number is your band size.
Globally, a natural female breast has an average size somewhere between a large "A" and a smaller "B" in the US size system. According to European or Australian classifications, this would be a "B".
Actually, 36D and 38C are around the same size. It's just that 38C is slightly bigger than 36D. 38C has 38 inches of underbust measurement and 41 inches of busts measurement. Meanwhile, 36D has 36 inches of underbust measurement and 40 inches of busts measurement.
Sister sizes are groups of bra-size equivalents that are related by cup volume. For example, a 36F (DDD) cup belongs to the same family as a 38E, a 40D, and a 42C.
38d bra size is a gorgeously larger bust structure that can be embraced by adorning a Sexy Bra. The sister size down would be a 36dd, and the size up will be a 40c Padded Bra equivalent.
Proper cup fit is influenced by band size. As the band size changes, so does the cup size. For every band size you go down, you should go up one cup. If you are in a 34D with a good cup fit, but want to go down to a 32 band, you would go to a 32DD for a tighter band with the same cup fit.