thumb|A comparison of the A4 and Foolscap folio papersize
Foolscap folio, commonly contracted to foolscap or cap or folio and in short FC, is paper made in or cut to the size of 8.5 × 13.5 in (216 × 343 mm) for printing or to 8 × 13 in (203 × 330 mm) for "normal" writing paper (foolscap). This was a traditional paper size used in some parts of Europe, and the British Commonwealth, before the adoption of the international standard A4 paper.
Size
A full (plano) foolscap paper sheet is actually in size, and a folio sheet of any type is half the base sheet size.
{|class="wikitable"
|+ Foolscap folio
! Name !! inch × inch!! mm × mm !! AR !! Characteristic
|-
! Foolscap folio
| 8½ × 13½|| 216 × 343 ª || 1:1.5879 ||Imperial (half foolscap), printing
|-
! Foolscap folio
| 8 × 13|| 203 × 330 || 1:1.6256 ||Traditional British, writing
|}
ª <small>Approximate measure in current use in Latin America: 216 x 341 mm.</small>
Ring binders or lever arch files designed to hold foolscap folios are often used to hold A4 paper (). The slightly larger size of such a binder offers greater protection to the edges of the pages it contains.
History
Historically, there were two prevalent foolscap folio paper sizes: British foolscap and imperial foolscap. The British foolscap measured approximately 8.0 by 13.0 inches (203 mm by 330 mm) and was widely used in the United Kingdom for official documents and administrative records. On the other hand, the imperial foolscap was slightly larger, measuring around 8.5 by 13.5 inches (216 mm by 343 mm). This larger format was preferred in some regions of the British Empire for similar purposes. Both paper sizes represented an era when handwritten records and official documentation were prevalent, but they have since faded into history, replaced by contemporary paper standards.
Europe
thumb|Two versions of the Fool's Cap watermark from 17th-century EnglandFoolscap was named after the fool's cap and bells watermark commonly used from the 15th century onwards on paper of these dimensions. The earliest example of such paper was made in Germany in 1479. Unsubstantiated anecdotes suggest that this watermark was introduced to England in 1580 by John Spilman, a German who established a papermill at Dartford, Kent.
The general pattern of the mark was used by Dutch and English papermakers in the late 17th and 18th centuries, and as early as 1674 the term "foolscap" was being used to designate a specific size of paper regardless of its watermark.
Apocryphally, the Rump Parliament of 1648–1653 substituted a fool's cap for the royal arms as a watermark on the paper used for the journals of Parliament. According to the Oxford Dictionary of Word Origins, there is no basis in fact for this statement.