Inch mm fractions

Inches

Abbreviation/Symbol:

• in
• " 

8 inches can be symbolised as either 8in or 8"

.

Unit of Measurement:

• Length / Distance / Diameter

Description:

An inch is a unit of length used in the imperial system, representing 1/12 of a foot and 1/36 of a yard

Origin:

The inch has been used as a unit of measurement in the United Kingdom since at least the seventh century, and in 1066 was defined as being equal to the length of three dried barleycorns placed end-to-end.

In the 12th Century, the Scottish inch was defined as being equivalent to the width of an average man's thumb at the base of the nail. Similar units of measurement existed in many areas of what is now modern Europe, with the word for inch in Portuguese, French, Italian, Spanish and numerous other languages being the same or very similar to the word for a thumb.

The English word inch derives from the Latin uncia, meaning one-twelfth part 

Even in the twentieth century, various definitions of the inch were still applied around the world, although these differed by less than 0.001%. In 1930 the British Standards Institution adopted an inch of exactly 25.4mm, with the American Standards Association doing likewise in 1933, and the first country to legally adopt this definition was Canada in 1951.

In 1959 the United States and British Commonwealth countries signed a treaty agreeing to the standardised 25.4mm definition.

Worldwide use:

The inch is still a common unit in the USA and is used in Canada and the United Kingdom. In all areas, the metric system of measure is the dominant system.