The first number is the band size, measured by the circumference of the underbust. To get the cup size via _the most common method_, you measure the loose circumference around the chest at the highest part of the breasts (typically over the nipples but not always) and subtract the underbust measurement, that then conveniently converts to letters in some of the most non-standardized fashion measurements in existence. I’m going to use inches because of convenience, but you can imagine how much worse things get when you have to convert metric measurements as well because fashion doesn’t like SI.
In all but Italy and Japan, less than 1 inch difference is AA-cup. Italy doesn’t have a size for this because apparently Italians don’t think bee stings need bras. Japan calls it A-cup; also Japan is simple because from there for every inch you move the letter up one.
Everywhere but Japan, 1 inch difference is A-cup. 2″ is B, 3″ is C, 4″ is D. At 5 inches we start to see variation. In North America it might be DD or E depending on brand and year, even season. In the UK, Italy, and Oceania, it’s DD. Most of Europe calls it E, and Japan is sitting at F now.
6″ is either DDD or F in NA; E in the UK, IT, and Oceania; F in Europe; and G in Japan.
7″ is DDDD or G in NA; F in the UK, IT, and Oceania; G in Europe; and H in Japan.
Now we get _really_ funky. 8″ is H in NA and Europe; FF in the UK and Italy; in Oceania it’s G, and I in Japan.
9″ is I in NA and Europe; G in the UK and IT; H in Oceania; and J in Japan.
10″ is J in NA and Europe; GG in the UK and Italy; I in Oceania; and K in Japan.
They all follow their patterns for anything larger. NA, Europe, Oceania, and Japan all just move to the next letter for every additional inch; though Oceania is a letter behind NA and Europe, and Japan is a letter ahead. The UK and Italy double the letter before moving on to the next one: H, HH, I, II, etc.
All said and done, it’s no surprise an overwhelming majority of women are wearing the wrong bra size. And that’s not even mentioning the fact that both the underbust and bust can grow and shrink in response to seasons, diet, exercise, medication, sexual activity levels, pregnancy, menopause, hell some women have to have two sets of bras for opposite ends of their menstrual cycles!
Further complicating matters is the fact that metric-focused countries may or may not use 2cm increments for cup sizes instead of 1″ increments, and sometimes this is a problem even within the same _brand_. Even worse is that how any particular bra manufacturer does the sizing during manufacture isn’t standardized either, so one American manufacturer’s 32C might be another’s 34C.
And then there’s so-called “sister sizes”. Basically they’re the sizes of bras with the same cup _volume_ but different band measurement, so if your band size isn’t quite feeling right you can try them out and still have the boobs fit in the cup properly. Basically go down a cup and up a band size, or up a cup and down a band size. This is a thing because bands are typically manufactured in 2″ increments so someone might be a 31B but have to either go 30C or 32B to find a fit that’s comfortable and doesn’t have “gapping” (where the bra is floating away from the skin in a relaxed but upright posture) or “spillage” (I don’t think this needs explanation). Most bras now have multiple clips for adjusting band size within those 2″, but sometimes the best solution is using a sister size.
Lastly, left and right breasts are different sizes. In up to 10% of women, this fact is so drastically true that they have no choice but to have custom bras made as no manufacturer makes a “customize your own padding” bra with a drastic enough difference between the two that they can be comfortable.
In short, using bra sizes is a quick shorthand. Nothing more. Good for a quick idea if you understand the system, terrible for the vast majority of both men and women to use for anything accurate. For the record, plastic surgeons use a _much_ better system that’s actually somewhat standardized and is far more accurate, plus differentiates between left and right – 34-B-C for example is a 34″ underbust with an 8″ “swell” over the left breast and a 9″ swell over the right breast. Women who have issues finding a comfortable bra based on the under-over method may have better luck using the plastic surgeon method.
NOW ON TO THE TUMBLR POST
It’s bullshit from the start. First of all, just from the fact that she goes, in order, DD, DDD, then E when guessing at Pyrrha’s sizing; she doesn’t actually know how bra sizing works. Just as a reminder, in the USA, DD and E are the same size. Secondly, while she’s right that compression is a thing, there’s no way Pyrrha’s tits jut out 5″ from her body. And the compression explanation is also BS. There’s no telltale signs of compression where the flesh is visible (spillage is still a thing, compression really only works as a possibility when the whole package is covered by a shirt or something), and her armor actually shows gapping, which indicates that if anything her breasts are quite comfortably not being squished. It’s possible that Pyrrha _might_ have pulled them down then bound them, but seeing as how this is both extremely uncomfortable and impressively impractical, plus her armor wouldn’t really allow it anyway, I highly doubt that. While I’m out of practice with eyeballing sizes, I’d hesitantly put Pyrrha’s rack at 34D on the large side, more likely 34C. 34 and not 36 because she’s a teenager and she’s really not much wider in the underbust than anyone else. A heavy focus on upper body strength _can_ increase your underbust but comparing her to those around her who have less intense upper body regimens, she’s not significantly larger so I can confidently guess she’s well within the average range for an athletic 17 year old.
I’m not going to go through them all since it’s now 0200 my time, but maybe tomorrow if someone wants it.
If you or anyone else have any further questions about anything I talked about, I can probably answer them.
Source: former employee of Victoria’s Secret.