A was on the smallest snap setting in his Bum Genius diapers, but it was starting to leave red marks that didn't go away on his waist so it seems they are getting a bit too tight. I moved both sides out to the next snaps (four snaps in on both sides) and it seemed too loose. So I went lopsided and did four snaps on one side and five on the other and that seems to be working for now, but I wondered what others have done.

Seems like it is kind of a trial and error thing to figure out which size is going to fit best.