A sheet cake pan is a large, rectangular dish into which cake batter is typically poured and placed into an oven for baking. These are usually rather shallow, since they are intended for multiple layers of cake to be stacked onto each other after baking and then frosted and served. A "full" sheet cake pan is typically about 18 inches (45.72 centimeters) by 26 inches (66.04 centimeters), though the length can also be only 24 inches (60.96 centimeters). In addition are half-sheet pans, usually about 13 inches (33.02 centimeters) by 18 inches (45.72 centimeters), and quarter-sheet pans that are 9 inches (22.86 centimeters) by 13 inches (33.02 centimeters) in size.
The basic design of a sheet cake pan is quite simple. It is typically rectangular in shape, often made of metal that is able to withstand the high heat of an oven without warping. These pans are fairly shallow; in these pans a thin cake can be made, which is stacked with others to make a single cake with multiple layers. This type of sheet cake pan has a lip, which allows the batter poured in it to stay in place, and provides a baker with something to grip while moving it into or out of an oven.
A full sheet cake pan is quite large, typically used in commercial baking rather than in home kitchens. Although they can vary somewhat in size, generally this type of pan is about 18 inches (45.72 centimeters) by 26 inches (66.04 centimeters) in width and length. Sometimes they can be 24 inches (60.96 centimeters) in length, though this difference is fairly negligible in terms of output and how many people can be served such a cake.
Many bakeries also use a half sheet cake pan, which is about 13 inches (33.02 centimeters) by 18 inches (45.72 centimeters) in size. This is based on the previous sizes of a full sheet pan, so there are some models that are only 12 inches (30.48 centimeters) in width. In this sheet cake pan, the difference is quite minor, since it would only be about a half inch (1.27 centimeters) from each side of the cake.
The smallest type of sheet cake pan is referred to as a "quarter" and is typically about 9 inches (22.86 centimeters) by 13 inches (33.02 centimeters) in width and length. Manufacturers that make the 24 and 12 inch (60.96 and 30.48 centimeters) sizes typically create a pan that is 9 inches (22.86 centimeters) by 12 inches (30.48 centimeters) instead. At this scale, the difference in size is still only half an inch (1.27 centimeters) from each side of the cake.