This is how they are defined: Inch An inch symbol: in is a unit of length.
It is equal to 0.
56.25 Inches to Centimeters
It is also the base unit in the centimeter-gram-second system of units.
Current use: The centimeter, like the meter, is used in all sorts of applications worldwide in countries that have undergone metrication in instances where a smaller denomination of the meter is required.