My 6 year old has a very tiny waist. I ordered the size 4 and 5 to compare. The size 5 shorts waist measured about 10.5” across, but the size 4 were bigger ~11 to 11.25” across. The Jean shorts are well made and the inside of the waistband where it says Levi’s is very soft and stretchy. There’s also the button elastic adjuster to make the waist smaller if needed. But perhaps the size 4 is wider for more of a toddler that needs diaper accommodation? The size 4 is significantly shorter in inseam as well.