I initially ordered a large but the bottoms were too small in terms of backside coverage. I reordered in an XL. The top still fits even though I am a small A bc it is similar to a sports bra and I have broad shoulders. The bottoms now are a bit loose but they are very comfortable and they aren't baggy. Definitely order a size up if you have a backside. It is a great suit. Can't wait for pool weather!