I'm a 32A and wasn't sure about XS vs. S - many sports bras in XS tend to feel too tight, which ended up being the case with this swim top. I can wear it but it feels a bit too constricting in the band; if it hadn't been final sale I would've exchanged it for S. For reference, the band is about 24 inches in circumference (unstretched). I like the style, though!

Fits a little small in my opinion. But once you get the right size is comfortable and flattering. Love it! I am small chested and usually fit S but ordered M in this which was not as tight .

Love this style, had to order in a different size as it was a big small for me. I am about a 36 A and the small fit but for me was a bit too tight especially around the neck. Medium fit well and the cup/chest area wasn't much bigger than the small. Haven't worn for active swimming yet but I bet it would be great for this.