First of all, take measurements. Measurements should be used as a guide, not gospel, and they’re an important starting point. While wearing a good, supportive bra, measure just below your bustline. If the result is an even number, add 4 to get your bra band size (so, measure 34″, your band size is 38). If the result is an odd number, add 3. Now measure around the fullest part of your bust, and subtract your band size from that number (if you measure 40″, subtract 38 for a result of 2). That difference corresponds to cup size, which is 1″ per letter. So, a 1″ difference is an A cup, 2″ is a B cup, etc. In our example, the cup size is B (2″ difference), so the bra size is 38B.
Do you see from the first step how the cup size is related to the band size? Let’s say you lose weight everywhere but your bust stays the same size. So now, if you measure under your bust, you measure 32″ and your new band size is (add 4) 36. Your breasts stayed the same size. Are you a 36B? Absolutely not! Your breasts are now relatively larger to your torso, so your bust still measures 40″, but when you subtract your new band size 36, the result is 4″, so now you’d need a D cup. Your new size is 36D.
Knowing all that, next time you shop for bras, pick up 2 different D-cup bras and compare them. Pick up a 36D and a 40D. Have you already realized that the cups will be different sizes? The 40D cup will be larger because it is D relative to size 40. That same actual cup size on the 36 bra would be DDD. Bottom line? As the band size goes down, the same size cup goes up.
The next key thing you have to know when selecting a bra is that bras are styled differently to provide different solutions for different bodies. There are “full figure” bras as well as “average figure” bras. A full figure style will have cups of roughly the same depth as another bra, but it will provide more coverage higher on the bust and it may have additional support features such as an underwire or slings. An average figure style may have more spacing between the cups, or the straps may be set wider apart because they don’t have to provide as much support.
The key things to remember when selecting a bra are that a cup size is not a cup size is not a cup size, and the styling of a bra has as much to do with the support and the fit as the size. Keep these pointers in mind the next time you shop for a bra, and I’m certain you’ll get a better fitting bra than you ever did before!
*Sumber dari: http://www.ehow.com/how_4517942_select-right-bra.html