I have a 43lb 5yo daughter, a little on the shirt side. Wears 5t/6 in dresses but did have a smaller waist, more like 4t. The size small continually falls down, showing her crack ;). They  are also longer than I had hoped, only about maybe an inch above her knee. Too long for most shorts and a lot of dresses. She wears dresses to school and I was hoping to get underwear that could double as bloomers, but they are actually too long. Will be trying another style. However the quality was good, not too thin to me like others have said.