A double bed in the UK measures 4 feet 6 inches wide by 6 feet 3 inches wide (135 cm x 190 cm). Bed size, most of the time, refers to the dimensions of a mattress sitting inside the bed frame.
There are no standardized bed sizes in the UK and any reference to bed sizes will typically be referring to mattress sizes, which have a standardized size grading. The size dimension of the room where the bed is positioned in relation to other furniture is important when planning to purchase a double bed. A double bed is common and widely used size in the UK.