Eli5: Could someone please explain how bra sizing works?
In: Other
There are two measurements that make up a bra. Band size and cup size. So a 30B would be a 30″ band with cup size B.
The band size is literally the measurement around your bust in inches. Take a tape measure and wrap it around yourself just underneath your breasts – aka the place where the bottom band on a bra would sit. It should be tight to the skin but not creating any pressure or pressing. The size in inches is the band size.
Cup size is more nebulous, and covers how large your breasts are. It’s not based on any specific measurement because breasts come in all different shapes and sizes and are hard to measure consistently.
Average cup size will depend on your ethnicity somewhat. B/C is considered average for Caucasians. A-E are the “normal” size range.
The + on some sizes (e.g. “38D+”) denotes a half-size. A large D, but not quite large enough to be an E.
There are two parts – the chest measurement below the breasts and the cup size. So the 36 in a 36C bra is the measure in inches around the rib cage just below the breasts. This is the band size.
The cup size – C – in this example is typically measured by measuring the size around the chest at the fullest part of the breast – often where the nipple is. Subtracting the band size from this breast size results in a number that is used to estimate the cup size. So a measure of 39 inches around the fullest part of the breast minus the 36 inch band size leaves 3 inches. This is about a C cup.
In reality though, breasts and bras are not uniform and cup size may need to be adjusted for individual preference and to account for differences between brands/styles.
https://www.realsimple.com/beauty-fashion/clothing/shopping-guide/how-to-measure-bra-size
Please note brands have different sizes in different countries.
Inches vs cm in the band sizing is pretty straightforward conversion, but cups are a mess.
Sometimes it goes A, B, C, D, E, F, sometimes you get double letters once in a while (AA, A, B, C, D, DD, E).
Italian sizes are T1, 2, 3, 4 which makes zero sense at all, as cap and band increases at the same time.
Bra sizing is *wonderfully* imprecise.
The standard American way:
You measure your “under bust” (where a bra’s band sits) snugly. That’s your band. Round up if odd.
You measure your bust at the fullest point, then minus the band size from it. Every 1″ of difference is a cup size. (0 AA 1″A 2″B ect.)
However, you really should measure your lying bust and leaning bust too. As breasts are not all super perky bolt ons so you can have larger breasts than just the bust measurement is saying.
That’s the *easy* part.
Cup sizes is essentially an estimated volume, but breasts come in different roots (width of base where it “attaches” to the body) and projection (how much it sticks out in a sillote). Bras are built to accommodate different roots and projections but *are not labeled for WHAT*. A woman with a wide root and shallow projection can have DD breasts on paper but not fill out a typical DD bra and it looks goofy due to the cup being more Mellon shaped than bowl. She would need to hunt for a more bowl shaped bra.
Now you know why the “women wears bra that fits perfectly but is so worn it should be shoot” meme exists, because if you are remotely not average shaped bras will be a pain in the ass.
In theory, the number is inches around your ribcage right below your breasts and the letter is the difference between that and the measurement around the fullest part of your breasts, where each letter is about an inch. E.g. if you measure 32″ rib and then 34″ bust it’d be 32B, or if 32″ and 35″ then 32C.
In reality bodies are complicated and breasts come in all shapes and sizes and manufacturers don’t stick to the numbers anyway (just look at other clothes sizings and how much they vary) and there are many different kinds of bras. So good luck.
Feels somewhat weird to be a guy that’s able to answer this question but this page is a great place to start reading. https://www.abrathatfits.org/calculator.php
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