First, start with our Fit Guide to find your measurements: http://championsportsbras.com/fit-support-guide#fit-matters
Then follow these Six Secret Tips & Tests from Sports Bra Expert, LaJean Lawson, for scoring that perfect fit:
1. Put on your favorite, most comfortable, most naturally shaped ‘everyday’ bra before you wrap the tape around your chest. Big Avoids: Anything push-up, padded, or smash-me-down (like a compressive sports bra) that will distort your true curves and throw off the whole measurement scheme.
2. If ‘the girls’ try to escape the bottom of the bra when you raise your arms, try going down to a smaller band size to snug things up and keep them properly corralled.
3. Turn sideways and check the back of the rib band—if it’s pulling up and riding higher than the front of the bra, the band might be too large or the straps too short. Try a smaller band size to keep things anchored and release the straps a little (if they’re adjustable).
4. Look straight down—the center front of an encapsulation or underwire style should sit fairy flat on your chest. If it doesn’t, try going up a cup size.
5. If your breasts spill over at the sides or top of the bra (double-bubble!), you’re definitely going to need a bigger cup.
6. Folds, wrinkles or other looseness in the cup are your clue to go down a cup size for best support and to banish the chafing that can happen when your breasts are free to jostle around in a cup that is too loose.