I have to admit to not trying this out yet - simply b/c it is a little bit big on my daughter. I have read this particular swim diaper/brand runs small, but I disagree. My LO is fairly average size, and I'd say every so slightly on the chunkier side cs on the slimmer side.  She is 21.5 lbs, and this diaper says it fits 22-28lbs. Definitely not a snug fit around her legs at all, and even the waist isn't particularly snug. I like that this one has snaps on the side, butninguess I won't get to try it out for real until later in the season.