Luckily I read the reviews to find the right size (they run small). The label says 12, the listing says "Day 12, Age 9-10" and it fits my 7 year old like a dream (she is an 8 year old's height/height). We use it as a bathing suit. The baby does not like how the swimsuit straps sit and twist on her shoulders. So far we've worn it to the beach and pool. We will definitely clean up immediately. It probably won't hold up as well as a proper swimsuit, but she loves the style and the fit.