An inch (symbol: in or ") is a unit of length in the imperial and US customary systems of measurement. It is defined as exactly 2.54 centimeters.
Definition
1 inch = 2.54 cm = 25.4 mm. There are 12 inches in a foot and 36 inches in a yard.
Historical Origin
The word "inch" derives from the Latin "uncia" meaning "one-twelfth." Historically, an inch was defined as the width of a man's thumb or the length of three barleycorns placed end to end.
Modern Uses
- Screen sizes (TVs, monitors, phones)
- Pipe and bolt sizes
- Tire dimensions
- Construction materials in the US, UK, and Canada
- Paper sizes (US Letter is 8.5 × 11 inches)