Inch (in) Conversions
The inch (Symbol: in) is a unit of length in the (British) imperial and United States customary systems of measurement. Standards for the exact length of an inch have varied in the past, but since the adoption of the international yard during the 1950s and 1960s, it has been based on the metric system and defined as exactly 25.4 mm.
Inch Usage
In many other European languages, the word for "inch" is the same as or derived from the word for "thumb", as a man's thumb is about an inch wide. The inch is a commonly used customary unit of length in the United States, Canada, and the United Kingdom. It is also used in Japan for electronic parts, especially display screens. Inches are commonly used to specify the diameter of vehicle wheel rims, and the corresponding inner diameter of tyres – the last number in a Car/Truck tire size such as 235/75 R16.