Standard bed sizes are based on standard mattress sizes, which vary from country to country. Bed sizes also vary according to the size and degree of ornamentation of the bed frame. Dimensions and names vary considerably around the world, with most countries having their own standards and terminology. In addition, two mattresses with the same nominal size may still have slightly different dimensions, due to manufacturing tolerances, amount of padding, and support type. While beds are generally rectangular, more specialized shapes may be obtained by special order, such as circular beds. Mattress sizes may differ from bedding sizes. Nomenclature Naming standards on different bed sizes and their corresponding actual measurements can vary across national standards. Examples of such nomenclature are names like "Single", "Double", "Queen" or "King" size. Sometimes the naming standards are further divided by adding adjectives such as "Narrow", "Wide", "Extra Wide", "Long", "Extra Long" and so on, which also can vary across national standards. For example, a King size bed may measure (in width by length): in the UK. in New Zealand. in Portugal, but is also available in lengths. in Indonesia. in Singapore and Malaysia. in Australia. in India. in the US. Because of the growth of international trade and the above potential cause of confusion, bed sizes are becoming more standardized. In most countries, using the International System of Units, bed dimensions most often appear in centimeters, and often only by width and length. In the United States, Canada and other regions influenced by the former British Empire, dimensions are often in inches. Europe Europe may traditionally have had more variations in national bed size standards than any other part of the world, but in the recent years a few sizes have become more common than others. Bed sizes are defined in centimeters in all European countries, although supplementary Imperial equivalents are sometimes shown in the United Kingdom. Today, the most common widths sold by pan European retailers are: for single beds. for double beds. Other sizes are also available in some European countries (e.g., ), but the widths listed above are the most common when looking at the European market as a whole, while and (nominal) are more typical in the UK and Ireland. Today, the length is the most common bed length sold by pan-European retailers. Lengths of are often also available by special order. The longer beds are intended for taller people,