A bunk bed is a type of bed in which one bed frame is stacked on top of another, allowing two or more beds to occupy the floor space usually required by just one. They are commonly seen on ships, in the military, and in hostels, dormitories, summer camps, prisons.

Bunk beds are normally supported by four poles or pillars, one at each corner of the bed. A ladder is used to get to the upper bed, which is normally surrounded by a railing to prevent the sleeper from falling out. Some models also have a privacy curtain for the lower bunk. Because of the need for a ladder and the height of the bed, the top bunk of a bunk bed is not recommended for children under six years of age.