HOW TO MEASURE FOR YOUR BRA SIZE
Put a tape measure under your armpits, around your body, just underneath your breasts. Make sure to keep the tape measure flat, horizontal and fairly snug. If this measurement is an even number, this is your band size. If this measurement is an odd number, add 1″ (for example, a measurement of 31″ should be rounded up to the next even number, 32″).
While wearing a bra, measure loosely around the fullest part of your bust. Next, subtract your band measurement from your cup measurement. Each inch difference represents a cup size. For example: if your band measurement is 34″ and your bust measurement is 36″, the difference between these measurements is two inches, and your cup size is B.
|Less than 1″||AA Cup|
The correct band size is when you can wear the bra comfortably on the loosest hook (can be tightened as the elastic begins to wear out). It needs to be tight enough that the bra is still fairly supportive without weighing down heavily on the shoulder straps or pinching your back and rib cage too much. The band should fit comfortably and lay even from front to back.
If the band is roomy enough for you to comfortably fasten it on the tightest adjustment, try a smaller band. Remember to change your cup size if you change band size. For every band size you go down, you must go up by one cup size in order for the cups to remain the same capacity, and vice versa. If the bra is too big around the body requiring an adjustment from a 34B to a 32, try changing to a C cup. Conversely, if you go from a 34B to a 36, try changing to an A cup.
You should completely fill out the cup with no wrinkling of the fabric or space in the cups. You should not bulge out anywhere, even in low cut or pushup bras. The bra should be secure under the arm, in the center, and the entire bust should lay within the wire (if the bra has a wire). The wire should not be sitting too low on the rib cage or off the bust on the flesh by the underarm.
These steps are ONLY a guide as some bras you will require a different size depending upon the make, the stretch, and the coverage.