There's lots of reviews here regarding size and so forth - if I'd followed the directions apparently given by the bra designer, I would have ended up with a terrible fit. I got this bra in the same size as all my other bras (which have perfect fit) - I measured around my ribcage for the band size (being sure to look in the mirror to the side to make sure that it was parallel with the floor, DO NOT add any inches, that is a myth and you will end up with a too-big band size! for odd numbers, add an inch) and then in my best fitting bra, measured around the bustline. The difference between the two numbers accounts for cup size - 1" is A cup, 2" is B cup, and so on. This method worked perfectly for this bra. YES IT IS TIGHT but it loosens a bit over time, and tight is what you want with a sports bra like this one. Now, if you have implants the method might be a little different, I don't know.

In this thing, I can run, jump, do jumping jacks, I could be a trampoline artist with this thing. I wear a G cup. Can you understand how life-changing a bra like this is? In this thing, my breasts do not shake or move at all. Seriously. I usually keep it on the tightest setting, but sometimes will let it out a bit if I'm not doing a high-impact exercise.

This is not a bra to be wearing to lounge around the house or just hang out. It is a SERIOUS sports bra for serious activity. It's designed to hold your breasts immobile no matter how much your body is bouncing around. I find it really comfortable, after the initial 'gah! this is tight!'

To reiterate: Best Sports Bra Ever. I wish I could afford to buy another one or give them to all my female friends who do high impact sports. So great.