A double bed is also known as a full-size bed, and the dimensions are 53 inches wide and 75 inches long. It is important to note that the dimensions of a double bed may vary slightly depending on the manufacturer, but the difference is usually only a fraction of an inch. A double bed is suitable for a single sleeper or a couple who doesnt mind sleeping close together. The minimum recommended room size for a double bed is 9 feet 6 inches by 10 feet 6 inches.