The inch is an "
English" or "
Imperial" unit of
length, being the 1/12 of a
foot, and about 2.54
centimeters. This inch, along with the
feet,
bushels, and
pounds, is mostly used in the
United States of America, it being one of the few industrial nations of the world that still clings to it.
The Chinese inch ("tswen") is approximately 3.03 centimeters, to my best estimation, but it is infrequently used in most areas in favor of the metric system.