I measure about 36A, with a wide spaced chest. Finding a comfortable bra that fits has always been hard. I decided to order the medium and it fits me very well. I bought just one at first, and since it's so comfortable and fits so well I now have four. I'll be using these to replace all my old cross over nursing bras (which were starting to compress ducts and cause blockages and infections. I'm not getting any duct compression from this bra at all and I'm very hopeful this will solve my bra problem once and for all. Time will tell.