The suits are made from a stretchy material so have plenty of give in them. I would say they fit slightly larger because of this as my LO still is well in size 00 where some other brands he's in 0. They seem a good fabric for summer, unsure if warm for our Tassie winter but we have sleeping bags too. Oh and of course the main reason I got the suit is for fitting the cloth butt which works well. Also important, inbuilt fold over hands and feet, and a 2 way zipper, all features.