You can fit a gallon, but it's a tight fit and you'd have to remove a shelf. Don't count on keeping much else in there with the gallon. There are door shelves for beverages, not sure if a half gallon would fit there or not since those shelves don't seem to move for height or removal. The door is where we stash bottled waters and those fit nicely.
Basically a dorm size fridge, not made for full size groceries.