If you are small chested and petite like me (Louise), you probably tried the smallest band size in store with the smallest cup size, which is a 10A in Australia or 32A in most other countries, and still find it is way TOO BIG. So you look online for a smaller cup size: 32AA. Little did you know, this cup size is actually way too small for your chest and causes you a lot of discomfort. You are tiny chested, doesn't mean you are a AA cup.
1. CUP 'SIZE' IS THE SAME AS CUP 'VOLUME':
Incorrect! People think a D cup is always bigger in cup volume than an A cup. This is not true. The cup volume in a 30D is the same as a 32C, which is the same as a 34B and the same as a 36A!!! Yes, a 30D fits the same amount of breast tissue as a 36A. That is two different cup sizes with the same cup volume. This is called 'sister sizing'.
2. BRA SUPPORT IS ALL IN THE STRAPS:
Incorrect! 70% of your bra's support should be coming from the underbust band (gore and cradle), not the straps. With a new bra, you should fit snugly on the loosest hook. Majority of women wear a band size that is way too loose, which is the cause of a lot of your discomfort with bras (and wires)!
Most women with small breasts and frames wear a 32A bra (because that is the smallest band and cup in the shops) but a 32 band is equivalent to wearing a size M dress... they're making petite women who usually wear a size XXS or XS, wear a size M. Ridiculous when you think about it!
3. UNDERWIRES ARE VERY UNCOMFORTABLE:
Incorrect! The only reason it is uncomfortable is because you are wearing the wrong size so the wire digs into your sensitive breast tissue (a sign that you are wearing a cup that is way too small for you).
When you know your correct fit, underwire is your best friend supporting you silently. It's so comfortable that women fitted properly for the first time refuse to believe there is any underwire in the bra!
4. IF THE CUP GAPES, IT MEANS IT'S TOO BIG:
Not necessarily! If a cup is way too small, it can also gape. When a cup is way too small, it can cause your breast tissue to migrate to all the wrong places.
Also, with molded cups (cups without seams in them) they are very rigid and don't move well with your body which can cause gapping when you lean over despite the cup being the perfect volume for your breasts when you are standing upright.
5. IT DOESN'T MATTER IF YOU CALCULATE YOUR BAND FIRST, OR YOUR CUP FIRST:
Incorrect! Cup sizes are relative to band sizes (like a ratio of the band). Every inch difference between your band and bust is a cup letter (e.g. 1" difference = A cup, 2" difference = B cup).
So if you start with the wrong band size, you will get the wrong cup size! There is no way to know your cup size without first knowing your band size. Also, having the wrong band size will affect your fit, making your bra ride up and give you awkward gaps even though it's the correct cup volume.
It's 3 simple steps:
1. Find your underbust measurement in inches = band size
2. Find your leaning bust measurement in inches
3. Leaning bust - band = cup size
For simplicity's sake, this chart will help! But it's always best to learn how it's calculated by yourself.
Check out A Bra That Fits for more educational information.
Find your underbust measurement in inches. E.g. if you measured 30", you are a 30 band. If you measured 28" you are a 28 band. If you measured 29", round up to a 30 band. Always round up if your underbust is an odd number.
Lean over 90 degrees so that gravity will mimic the support a bra would provide your breasts. Firmly wrap the measuring tape around the fullest part of your bust (usually around the nipples). This number is your leaning bust measurement.
Each letter up in a cup size represents one additional inch difference between your leaning bust and band. 1" difference = A, 2" difference = B, 3" difference = C, 4" difference = D, 5" difference = DD, 6" difference = E, and so forth.
EXAMPLE:
If you measured 29 inches for your underbust, then your band size is 30. And if your leaning bust is 33 inches then 33 - 30 = 3. The 3rd letter in the alphabet is C, your bra size is a 30C.
IMPORTANT:
For your bust measurement, make sure you are leaning over 90 degrees when you take this measurement. This will mimic the support your chest will receive in a bra. If you measure while standing up, gravity is pulling your bust down and your measurement will be smaller than what it should be.
To discover your most accurate bra size we recommend using 'A Bra That Fits Calculator'.