ISO 216 in the context of "Tabloid (paper size)"

Paper size refers to standardized dimensions for sheets of paper used globally in stationery, printing, and technical drawing. Most countries adhere to the ISO 216 standard, which includes the widely recognized A series (including A4 paper), defined by a consistent aspect ratio of √2. The system, first proposed in the 18th century and formalized in 1975, allows scaling between sizes without distortion. Regional variations exist, such as the North American paper sizes (e.g., Letter, Legal, and Ledger) which are governed by the ANSI and are used in North America and parts of Central and South America.

The standardization of paper sizes emerged from practical needs for efficiency. The ISO 216 system originated in late-18th-century Germany as DIN 476, later adopted internationally for its mathematical precision. The origins of North American sizes are lost in tradition and not well documented, although the Letter size (8.5 in × 11 in (216 mm × 279 mm)) became dominant in the US and Canada due to historical trade practices and governmental adoption in the 20th century. Other historical systems, such as the British Foolscap and Imperial sizes, have largely been phased out in favour of ISO or ANSI standards.

Letter (officially ANSI A) is a paper size standard defined in ANSI/ASME Y14.1 by the American National Standards Institute, commonly used as home or office stationery primarily in the United States, Canada, and the Philippines, and variably across Latin America. It measures 8.5 by 11 inches (215.9 by 279.4 mm) and is similar in use to the A4 paper standard at 210 mm × 297 mm (8.27 in × 11.7 in) used by most other countries, defined in ISO 216 by the International Organization for Standardization.

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.

A filing cabinet (or sometimes file cabinet in American English) is a piece of office furniture for storing paper documents in file folders. In the most simple context, it is an enclosure for drawers in which articles are stored. The two most common forms of filing cabinets are vertical files and lateral files. A vertical file cabinet has drawers that extend from the short side (typically 15 inches or 380 mm) of the cabinet. A lateral file cabinet has drawers that extend from the long side (various lengths) of the cabinet. These are also called side filers in Great Britain. There are also shelf files which go on shelves. In the United States, file cabinets are usually built to accommodate 8.5 × 11 paper, and in other countries, filing cabinets are often designed to hold other sizes of paper, such as A4 paper.