Ok, girls, let's talk bras!  Having formerly worked at Victoria's Secret for over three years as a certified bra specialist, I've gained a great deal of knowledge on the subject, and would like to share it with you. 

The most common signs that you need a different bra size are:

• Your bra is riding up in the back
• The underwires are digging into your sides
• There's space between the center of the bra and your chest
• The "wings" of the bra don't lie flat against your ribs 

Studies have shown that up to 75% of women are wearing the wrong size, so it's very important that you measure carefully at least once or twice a year to ensure the greatest comfort and the best-looking fit.  (The idea that wearing a smaller cup size will make you appear larger is actually a myth--you may have more cleavage in a smaller size, but a smaller cup will hold you in or "squash" you, making your bust appear smaller beneath clothing. A good push-up bra in your true size will give you cleavage AND fullness, and be comfortable too!)  The sizing process isn't exactly simple, but I'll try to explain it in a straightforward manner.  It works best if a friend measures for you, but if you're careful you can get pretty accurate results by yourself.

1. Put on your best-fitting unlined/unpadded bra.  Measure snugly (but not too tightly) around your ribcage just beneath your bust and straight across your back.
2. If the measurement is an odd number, add 5".  If it's an even number, add 6".  This will give you your band size.  (For example, if your measurement is 29", you'd add 5, giving you a band size of 34.)
3. Now, still wearing your bra, measure gently around the fullest part of your bust, and straight across your back.
4. Take the resulting measurement, and subtract your band size from it.  (For example, if your bust measurement is 36", and your band size is 34, you would have a 2" difference.)
5. The difference between your band size and your bust measurement determines your cup size.  0" = AA, 1" = A, 2" = B, 3" = C, 4" = D, and so on.  (Once you're past a D cup, different manufacturers use different sizing--with some the next size would be DD, but with some it would be E.  If you are larger than a D cup, make sure you check with the manufacturer to find out how they size their bras.)

I hope that was fairly easy to follow!  Please don't hesitate to email me (FashionSecrets23 at Gmail) if you have any questions about bra fitting.  You will look and feel your best if you are wearing the right size!

Frequently Asked Questions

I seem to be between sizes--sometimes a B cup is a little too small, but a C cup is a little too big.  First, make sure you're wearing the correct band size.  Your cup size will vary depending on the band size--for instance, a 34C cup is about the same size as a 36B cup, but they will have a slightly different shape.  If the band sizing is right, try wearing a C in demi style bras, as they tend to fit a little smaller, and a B in full-coverage bras, as they tend to fit a bit larger.  A bra with a light lining, or a push-up bra with removable "cookies", is also a good choice if you're between sizes.

My left breast is noticeably larger than my right, making it difficult to find a bra that fits well.  It's perfectly normal for one breast to be larger than the other; almost all women experience this, some to a greater degree than others.  You might try a lightly-lined style with removable "cookies" so that you can remove the one from your fuller side, and even add it to your smaller side if needed.  If you prefer an unlined style, try to find one with very stretchy cups in the size that best fits your smaller side.

I can't find a strapless bra that will stay up well.  What do you suggest?  Many women hook their strapless bras as tight as they will go, thinking this will hold them up better.  In reality, this usually causes them to slide down more easily, since the average woman's torso is essentially cone-shaped--getting smaller toward the waist.  In my experience, the best strapless bras have at least a lightly-lined cup (since there is no strap to support the breast) and a strip of silicone along the inner edges of the bra to provide traction against your skin (similar to that in a thigh-high stocking)...and of course, be sure to use the most comfortable hook setting, rather than the tightest one.