The standard dimensions for a UK Single mattress is 90 x 190 cm / 3 ft x 6ft 3in. You may need a slightly smaller mattress for bunk beds or cabin beds which are normally 75 x 190 cm / 2ft 6 x 6ft 3in. Manufacturers often advise that if you are buying a new mattress you should also invest in a new bed or base. There is an extensive range of Single mattressES from retailers Argos, coopbedshop.co.uk and Tesco. Popular brands include Silentnight, Layezee, Nestledown and Sealy.