I normally where at US size 22/24. I got an XXL expecting it to be snug and work as a base layer and that is accurate. I would say even if I were an 18/20, it would be a little form fitting, but not too tight. I would have been happy to get this in 3X and wear it as a shirt without another layer, but that wasn’t available.I like the light weight stretchy fabric. Its not so light weight as to be see through. Nice and solid. I got the peach which I like. I don’t know why its called "heathered peach” Looks like a solid peach to me.The sleeves are normal length, which is very much appreciated.The neck is not designed to button up but to keep it half way buttoned like shown.