This depends on the brand and makes of the diaper case. However, on average, at least 4 to 5 changes should fit comfortably. If you feel you require less or if your child is older, you can choose a smaller one. It is also very compact and makes travelling easy. However, for young kids or if you have more than one toddler, you may require a bigger one. You can consult a doctor or a person from your family or any friend to understand which one is needed. Make sure you make an informed one so you don’t have to go for another smaller or larger one later.