1In

1 inch, often written as 1 in, is a unit of length in the imperial and United States customary systems. It is exactly 2.54 centimeters (25.4 millimeters). Defined in 1959 as 1 inch equals 1/36 of a yard, since then 1 yard equals 3 feet and 1 mile equals 63,360 inches.

In typography, 1 inch equals 72 points, with a point defined as 1/72 of an inch, and 1 inch equaling 6 picas. These relationships underpin printing and page layout.

In computing and web design, CSS uses the inch as a length unit, with 1in defined as 96 CSS pixels. Actual on-screen length can vary with display density and device pixel standards.

Notation and history: the abbreviation 'in' is widely used, and the inch can be denoted by the double prime character (″) in written text. Historically, the inch derives from a Roman uncia and was adopted into English measurement systems.

Usage: inches are common in design, manufacturing, construction, maps, and consumer products in the United States and other countries that use the imperial system.