When diapering a baby or diapering a toddler the diaper should be tight enough to not cause leaks and sag but also not tight enough to where it's uncomfortable or causes marks on the babies waist.
When putting a diaper on your baby or toddler place two fingers in the top waistband of the diaper and if you can easily fit the fingers into the diapers waistband then the diaper is not too tight.
But if you cannot fit two fingers in the top of the diaper with ease then it's too tight.
Also if you notice any red marks on the babies waist then the diaper is too tight and should be loosened.
When you put a diaper on a toddler or baby make sure you pull the diaper tabs tight enough so that there's not much of a gap in the waist but do allow a little gap and do not stretch the tabs to where they will fit.
If the diaper tabs have to be really stretched to get the diaper on the child then you need to get bigger diapers.
When you put a diaper on a baby or toddler the tabs should be spaced apart between 2 to 5 inches at the point they meet which means that the diaper is not too tight.