The inch is a unit of length for measuring small distances, primarily used in the USA. It equals 1/12 of a foot and 2.54 centimeters.
Initially used in England, the inch started spreading into the rest of the world from the 7th century onwards. Depending on the country and cultural context, its length was defined in relation to the human foot, the thumb and finger or as a multiple of the length of a barleycorn.
Today, the inch serves as an official unit of length only in the USA. Unofficially, it’s still popular in countries that used the imperial system, such as Great Britain, Ireland and Canada. Moreover, the inch is still in worldwide use for technical specifications such as the size of TV, laptop or smartphone screens. The same is true for clothing sizes, where the inch is used to measure waist and inseam length.
The English word “inch” is phonetically derived from the Latin “uncia” (one twelfth), since an inch was defined as one twelfth of a foot.
| Inches | |
|---|---|
| Marathon | 1,661,220.5 |
| Race track "Mille Miglia" | 63,358,267.7 |
| Earth radius | 251,108,858.3 |
| Earth circumference | 1,577,763,464.6 |
| Distance earth ↔ moon | 15,133,858,267.7 |
| Distance earth ↔ sun | 5,889,518,897,637.8 |