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.