I think you could put a gallon of milk inside one. I'm pretty sure that's what we did. We might've had to move one of the shelves out of the way to do it. I'd agree tey are dorm-sized, but the slightly larger dormed sized ones (rectangular front over the square cube-sized smaller dorm fridges) They are about the size of a mini-bar fridge, if that helps.
I think we were able to get a gallon of milk and some leftovers containers, if they were slightly askew. We also put some bottled water inside too. With two room though, we got smart and used one for milk and leftovers and one for lots of water.