LO only wears disposables at night and on Sundays. A box lasts us a very long time. I need to order some more, but I don't know if I should go ahead and get size 4s or size 3s. LO (13 mos) is about 18.5 lbs, and 3s fit her perfectly. She wears them overnight with no issues, but I have noticed them being much more soggy in recent mornings.