Large
I bought it in a larger size for a camp for extracurricular activities, but in the end, we managed to fit everything with other items, so I haven't used it yet. However, the fact that it can turn into a mini backpack and seems like it can hold a lot on the side made my child happy and helped in the decision. It wasn't too big for my 6th-grade son to carry. I thought it might be a bit big for my 2nd-grade younger brother, but it seems like it can be used for trips back home and I'm looking forward to using it from now on.