Important tips to test accuracy

Band Size

Try this little test Have someone put their fingers under the clasp. If the fingers slide in easily, it is too loose. They should be able to slide in snugly. But be careful, a lover doing that might get carried away. A new bra should be able to pass this test with the clasp on the first loop - this allows you to tighten the bra as it stretches with wear and washing.

Cup Sizes

Your bra cups should be large enough to prevent breast tissue from bulging or spilling out over the neckline or armhole edges.

You'll know if your bra cups are too large if they have wrinkling, or are clearly larger than both of your breasts.

Underwires

Your breasts have a natural "crease line" where the underwire should fit comfortably against your ribcage. The diameter of your underwire is too small if the underarm end is poking breast tissue, or catches your arm as it moves forward. The diameter of your underwire is too large if your underarm is poking into your armpit. The best underwire for you is one that encircles your breast, giving you a more rounded and defined look.

		Center Panel : The center panel of your bra should rest firmly against your chest (sternum). However, there are some exceptions. Wire-free bras and women with full breasts close together may not be able to achieve a center panel touching their sternum. This is fine. This actually can help you in determining which style suits you best.
		Straps : Shoulder straps on a bra should rest flat on your shoulders. They shouldn't cause dents or fall off your shoulders. Shoulder straps are designed to carry minimal breast weight. If your shoulders have dents from your straps, then your straps are working too hard - you probably need a smaller band size to give your bra more support. If your straps keep slipping, there are several possible causes.

The first problem could be the placement of the straps on your bra may be too wide. This is normally a problem in push-up bras because push-ups have wider straps in order to push the breasts up to maximize cleavage. To solve this problem, you can look at bras that have the straps starting right in the middle of the cup or those with a racerback styling.