They can hold a gallon of milk, though you may need to remove the lowest shelf. The fridges are about 18" wide by 34" tall. Similar to the one shown in this photo
Deb's site has a good picture of an OKW mini kitchen at http://www.allearsnet.com/acc/okw31.jpg . For Gallons of milk, you will need to remove the shelf. 1/2 gallons if I remember correctly will fit in the door.