Foolscap is a size of paper, traditionally 13.5 inches (34.3 cm) by 17 inches (43.2 cm), although it might be a bit smaller. It is commonly divided into halves, and the paper size of 8.5 inches (21.6 cm) by 13.5 inches (34.3 cm) is known as foolscap folio or simply folio paper; the word "folio" means half a sheet of paper. The folio size might also be referred to as foolscap in some cases. Foolscap and foolscap folio were once widely used in certain parts of the world, such as England, but they have become less common than they once were. The term "foolscap" might also be used loosely to refer to any paper that is in a large format.
This size of paper became a standard paper size during the 15th century, when it was first produced in Germany. It gets its name — typically pronounced full-scap or full-scape — from the watermark that was once used to identify it. The watermark was in the shape of a jester's hat, or fool's cap. Full-size foolscap sheets were divided into halves, quarters and eighths to produce other standardized paper sizes, called folio, quarto and octavo, respectively.
Less Common Today
Foolscap folio was the most widely used paper size throughout Europe and the British Commonwealth of Nations until the introduction of the International Organization for Standardization (ISO) 216 standard in 1975. This standard defined many sizes of paper, of which A4 is most commonly used today. A4 paper, which measures 8.3 inches (21.0 cm) by 11.7 inches (29.7 cm), is considered standard for most of the world. Some notable exceptions are the United States, Canada and Mexico, which typically use letter size paper that is 8.5 inches (21.6 cm) by 11 inches (27.9 cm).
The term "foolscap" is most often heard in England, Australia and Canada. In some Spanish-speaking countries, foolscap folio is known as oficio. This paper size can sometimes be found at specialty stationers and less commonly at stores that carry office or school supplies. In the U.S., a paper size that is similar is called legal paper, which is standardized as 8.5 inches (21.6 cm) by 14 inches (35.6 cm).