This bra, now that I have figured out my size, is fast becoming my go-to for casual summer mommy wear. I already own three and have just ordered two more, since in the punishing Texas heat, it is impossible to wear a bra more than once without washing it. I wear a size medium in most clothes and a 36C in bras. But in this bra, it takes an XXL for me to feel comfortable. That size is large enough that I can breathe without my rib cage being crushed, while still being snug enough to support my every day activities and walking.  I would NOT go out and do jumping jacks in this thing.