I can generally fit a standard medium bikini top. I should have erred on the side of caution and ordered a large but honestly, the way it's cut is weird. I get the general concept of triangle bikini tops, but this one seems to have a LOT less coverage than most. If you're busty (and don't need support) go up at least 2 sizes.
It's not made very well, there's a number of threads hanging from it that I had to cut off, and I don't expect it to last more than a few wears but I just need it to get me through this summer.
I'm keeping the top since I'll have a rashguard over it anyway and it matches the bottoms I already have.