Bra Fit Mathematics

Drastic changes in cup size can come as a shock after a proper bra fitting. When you understand the math behind the measurements, it's much easier to accept.

Cups and Measures shared a clear and informative description she found on reddit in her blog.
http://cupsandmeasures.wordpress.com/2012/06/12/reddit-to-the-rescue-8/

"The letter is a measurement of the difference between the whole boob measurement and the around the ribcage under the boob measurement. So as the number (ribcage measurement) gets smaller, the same sized “boob measurement” gets larger, as the difference would be growing, giving you a higher cup size.So in this case, she thought she was 34C and found out that she was actually 32E, right? Her “boob measurement” (presumably 37″) is the exact same it was, meaning her boobs are actually no different, but the “ribcage measurement” is two inches less than she thought it was (she thought it was 34, but it was actually 32). This means that the difference between the two is actually 5″ different instead of 3″ which, according to the chart given to us by mywifesbusty, changes her assumed cup size from C to her actual cup size of E.The easiest way I can think of this is imagine huge boobs on a small woman. Then imagine the exact same boobs on a larger woman. The boobs seem to be more noticeably large on the little woman, giving her a bigger cup size out of the deal."

Butterfly Collection's "5 Reasons Your Bra Straps Slip"

Do your bra straps often slip off of your shoulders? It might be time to start trying on a different bra size. The exact reason why it's happening to you could be one of these 5 described on Butterfly Collection's blog:

1. Your Band is Too Big
2. Your Cups are Too Small
3. Your Cups are Too Big
4. Your Bra is Designed for Taller Women
5. Sloping Shoulders

For more details on each of these reasons, read their blog post: http://blog.butterflycollection.ca/2012/10/5-reasons-your-bra-straps-slip.html

Cup Sizes Depend on Band Sizes

http://www.frmheadtotoe.com/

Cup sizes aren't fixed. The volumes of a cup actually depend greatly on the band that supports it. Butterfly Collection has written a great comprehensive description on how cups relate to bands, clearly explains the math and reason behind it, and even created a fantastic chart that makes it all easy to understand! Here's an excerpt:

"One of our most popular blog posts is ‘Not All D Cups Are The Same’ which explains that the volume of D cups (all cups in fact) gets bigger as the band size gets bigger. This is why a woman wearing a 32E can also wear a 34D because the cup volume is the same, only the band is different. 

Lots of women were interested in the topic but asked for some more explanation. Today's post goes into more depth about why the volume of the same cup letter gets bigger as the band gets bigger. 

What Would We Look Like If All Cup Sizes Really Were The Same Volume?As regular readers will know, cup sizes simply acknowledge the difference between a woman’s ribcage measurement and her full bust measurement. So for example both these women have D cup breasts because they both have a four inch difference between their ribcage and full bust measurements: 
Woman A is a 30D (Ribcage = 30 inches, Full Bust = 34 inches)
Woman B is a 38D (Ribcage = 38 inches, Full Bust = 42 inches)
So why does Woman B with a 38D bust look bustier than Woman A who has a 30D bust? The answer is that Woman B's bust is PROPORTIONALLY bigger than Woman A.
To put this into context let's take the 30D breasts from Woman A and put them on women with 32, 34, 36 and 38 bodies to see what it looks like..."

Read the rest of this brilliant post on their website: http://blog.butterflycollection.ca/2012/09/why-do-cup-volumes-get-bigger-as-band.html