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:''For other meanings, see Inch (disambiguation).''
An 'inch' (plural: 'inches'; symbol or abbreviation: 'in' or, sometimes, ″ - a double prime) is the name of a unit of length in a number of different systems, including English units, Imperial units, and United States customary units. Its size can vary from system to system. There are 36 inches in a yard and 12 inches in a foot. A corresponding unit of area is the square inch and a corresponding unit of volume is the cubic inch.
The inch is one of the dominant units of measurement in the United States, and is very commonly used in Canada. In the US and commonly in the UK, Australia and Canada, personal heights are expressed in feet and inches by people of all ages. In Canada, personal heights are shown in metric units on official documents such as a person's driver's license.

Contents

International inch

Historical origin

See also

International inch

In 1958 the United States and countries of the Commonwealth of Nations defined the length of the international yard to be exactly 0.9144 meters. Consequently, the international inch is defined to be exactly 25.4 millimeters.
The international standard symbol for inch is 'in' (see ISO 31-1, Annex A). In some cases, the inch is denoted by a double prime, which is often approximated by double quotes, and the foot by a prime, which is often approximated by an apostrophe. For example, 6 feet 4 inches is denoted as 6′4″ (or approximated as 6'4").
an inch isnt very big there are 15 inches in one foot

Historical origin

Swedish: ''tum'' inch, ''tumme'' thumb; Dutch: ''duim'' inch, ''duim'' thumb; Sanskrit: ''Angulam'' inch, ''Anguli'' Finger.
Given the etymology of the word "inch", it would seem that the inch is a unit derived from the foot, but this was probably only so in Latin and in Roman times. In English, there are records of precise definitions for the size of an inch (whereas the definitions for the size of a foot are probably anecdotal), so it seems that the foot was then defined as 12 times this length. For example, the old English ''ynche'' was defined (by King David I of Scotland in about 1150) as the width of an average man's thumb at the base of the nail, even including the requirement to calculate the average of a small, a medium, and a large man's measures. To account for the much larger length later called an inch, there are also attempts to link it to the distance between the tip of the thumb and the first joint of the thumb, but this may be speculation.
There are records of the unit being used circa AD 1000 (both ''Laws of Æthelbert'' and ''Laws of Ælfred''). An Anglo-Saxon unit of length was the barleycorn. After 1066, 3 barleycorn was equal to 1 inch; it is not clear which unit was the base unit and which the derived unit.
One source says that the inch was at one time defined in terms of the yard, itself supposedly defined as the distance between Henry I of England's nose and his thumb. This is unlikely as Henry was born in 1068.
Prior to the adoption of the international inch (see above), the United Kingdom and other countries of the Commonwealth of Nations defined the inch in terms of the Imperial Standard Yard. The United States and Canada each had their own, different, definition of the inch, defined in terms of metric units. The Canadian inch was defined to be equal to 25.4 millimeters.

See also

★ English unit

★ Imperial unit

★ United States customary units

★ Gry

★ Pyramid inch

★ Guz

★ Inch (Scots)